Globin: Difference between revisions
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imported>Robertpedley →Sequence conservation: fixed wikilink, added {{CN}} template |
imported>Chimproach I removed all broken links. I also standardized the spelling of all instances of heme/haem and hemo/haemo to heme and hemo for the sake of consistency (given that the main sections of this article and the majority of heme-containing article titles use the American spelling). |
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== Structure == | == Structure == | ||
Globin superfamily members share a common [[Tertiary structure|three-dimensional fold]].<ref>{{cite book|title=Introduction to protein structure|last2=Tooze|first2=John|date=1999|publisher=Garland Pub.|isbn=978- | Globin superfamily members share a common [[Tertiary structure|three-dimensional fold]].<ref>{{cite book|title=Introduction to protein structure|last2=Tooze|first2=John|date=1999|publisher=Garland Pub.|isbn=978-0-8153-2305-1|edition=2nd|location=New York|last1=Branden|first1=Carl}}</ref> This 'globin fold' typically consists of eight [[Alpha helix|alpha helices]], although some proteins have additional helix extensions at their termini.<ref>{{Cite journal|last2=Onesti|first2=S|last3=Gatti|first3=G|last4=Coda|first4=A|last5=Ascenzi|first5=P|last6=Brunori|first6=M|year=1989|title=Aplysia limacina myoglobin. Crystallographic analysis at 1.6 a resolution|journal=Journal of Molecular Biology|volume=205|issue=3|pages=529–44|pmid=2926816|last1=Bolognesi|first1=M|doi=10.1016/0022-2836(89)90224-6}}</ref> Since the globin fold contains only helices, it is classified as an [[all-alpha protein fold]]. | ||
The globin fold is found in its namesake globin [[Protein families|families]] as well as in [[phycocyanin]]s. The globin fold was thus the first protein fold discovered (myoglobin was the first protein whose structure was solved). | The globin fold is found in its namesake globin [[Protein families|families]] as well as in [[phycocyanin]]s. The globin fold was thus the first protein fold discovered (myoglobin was the first protein whose structure was solved). | ||
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== Evolution == | == Evolution == | ||
Globins [[evolution|evolved]] from a common ancestor and can be divided into three lineages:<ref name="pmid16061809">{{cite journal |last1=Vinogradov |first1=SN |last2=Hoogewijs |first2=D |last3=Bailly |first3=X |last4=Arredondo-Peter |first4=R |last5=Guertin |first5=M |last6=Gough |first6=J |last7=Dewilde |first7=S |last8=Moens |first8=L |last9=Vanfleteren |first9=JR |title=Three globin lineages belonging to two structural classes in genomes from the three kingdoms of life. |journal=Proceedings of the National Academy of Sciences of the United States of America |date=9 August 2005 |volume=102 |issue=32 |pages=11385–9 |doi=10.1073/pnas.0502103102 |pmid=16061809|pmc=1183549 |doi-access=free }}</ref><ref name=pmid23541529>{{cite journal |last1=Vinogradov |first1=Serge N. |last2=Tinajero-Trejo |first2=Mariana |last3=Poole |first3=Robert K. |last4=Hoogewijs |first4=David |title=Bacterial and archaeal globins — A revised perspective |journal=Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics |date=September 2013 |volume=1834 |issue=9 |pages=1789–1800 |doi=10.1016/j.bbapap.2013.03.021 |pmid=23541529|url=https://www.zora.uzh.ch/id/eprint/81249/1/Vingradov-Hoogewijs_BBA-Proteins_and_Proteomics_2013-main.pdf }}</ref> | Globins [[evolution|evolved]] from a common ancestor and can be divided into three lineages:<ref name="pmid16061809">{{cite journal |last1=Vinogradov |first1=SN |last2=Hoogewijs |first2=D |last3=Bailly |first3=X |last4=Arredondo-Peter |first4=R |last5=Guertin |first5=M |last6=Gough |first6=J |last7=Dewilde |first7=S |last8=Moens |first8=L |last9=Vanfleteren |first9=JR |title=Three globin lineages belonging to two structural classes in genomes from the three kingdoms of life. |journal=Proceedings of the National Academy of Sciences of the United States of America |date=9 August 2005 |volume=102 |issue=32 |pages=11385–9 |doi=10.1073/pnas.0502103102 |pmid=16061809|pmc=1183549 |doi-access=free }}</ref><ref name=pmid23541529>{{cite journal |last1=Vinogradov |first1=Serge N. |last2=Tinajero-Trejo |first2=Mariana |last3=Poole |first3=Robert K. |last4=Hoogewijs |first4=David |title=Bacterial and archaeal globins — A revised perspective |journal=Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics |date=September 2013 |volume=1834 |issue=9 |pages=1789–1800 |doi=10.1016/j.bbapap.2013.03.021 |pmid=23541529|url=https://www.zora.uzh.ch/id/eprint/81249/1/Vingradov-Hoogewijs_BBA-Proteins_and_Proteomics_2013-main.pdf }}</ref> | ||
* Family M (for myoglobin-like) or F (for FHb-like),<ref name="pmid32863222">{{cite journal |last1=Keppner |first1=A |last2=Maric |first2=D |last3=Correia |first3=M |last4=Koay |first4=TW |last5=Orlando |first5=IMC |last6=Vinogradov |first6=SN |last7=Hoogewijs |first7=D |title=Lessons from the post-genomic era: Globin diversity beyond oxygen binding and transport. |journal=Redox Biology |date=October 2020 |volume=37 | | * Family M (for myoglobin-like) or F (for FHb-like),<ref name="pmid32863222">{{cite journal |last1=Keppner |first1=A |last2=Maric |first2=D |last3=Correia |first3=M |last4=Koay |first4=TW |last5=Orlando |first5=IMC |last6=Vinogradov |first6=SN |last7=Hoogewijs |first7=D |title=Lessons from the post-genomic era: Globin diversity beyond oxygen binding and transport. |journal=Redox Biology |date=October 2020 |volume=37 |article-number=101687 |doi=10.1016/j.redox.2020.101687 |pmid=32863222 |pmc=7475203}}</ref> which has a typical 3/3 fold. | ||
** Subfamily FHb, for | ** Subfamily FHb, for flavohemoglobins. [[Fusion protein|Chimeric]]. | ||
** Subfamily SDgb, for single-domain globins (not to be confused with SSDgb). | ** Subfamily SDgb, for single-domain globins (not to be confused with SSDgb). | ||
* Family S (for sensor-like), again with a 3/3 fold. | * Family S (for sensor-like), again with a 3/3 fold. | ||
** Subfamily GCS, for | ** Subfamily GCS, for Globin-coupled sensors. Chimeric. | ||
** Subfamily PGb, for | ** Subfamily PGb, for protoglobins. Single-domain. | ||
** Subfamily SSDgb, for sensor single-domain globins. | ** Subfamily SSDgb, for sensor single-domain globins. | ||
* Family T (for truncated), with a 2/2 fold<ref name="pmid26788940">{{cite journal |last1=Bustamante |first1=JP |last2=Radusky |first2=L |last3=Boechi |first3=L |last4=Estrin |first4=DA |last5=Ten Have |first5=A |last6=Martí |first6=MA |title=Evolutionary and Functional Relationships in the Truncated Hemoglobin Family. |journal=PLOS Computational Biology |date=January 2016 |volume=12 |issue=1 | | * Family T (for truncated), with a 2/2 fold<ref name="pmid26788940">{{cite journal |last1=Bustamante |first1=JP |last2=Radusky |first2=L |last3=Boechi |first3=L |last4=Estrin |first4=DA |last5=Ten Have |first5=A |last6=Martí |first6=MA |title=Evolutionary and Functional Relationships in the Truncated Hemoglobin Family. |journal=PLOS Computational Biology |date=January 2016 |volume=12 |issue=1 |article-number=e1004701 |doi=10.1371/journal.pcbi.1004701 |pmid=26788940|pmc=4720485 |bibcode=2016PLSCB..12E4701B |doi-access=free }}</ref> All subfamilies can be chimeric, single-domain, or tandemly linked.<ref name="pmid32863222"/> | ||
** Subfamily TrHb1 (also T1 or N). | ** Subfamily TrHb1 (also T1 or N). | ||
** Subfamily TrHb2 (also T2 or O). Includes 2/2 [[phytoglobin]]s. | ** Subfamily TrHb2 (also T2 or O). Includes 2/2 [[phytoglobin]]s. | ||
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The M/F family of globins is absent in [[archaea]]. Eukaryotes lack GCS, Pgb, and T3 subfamily globins.<ref name="pmid32863222"/> | The M/F family of globins is absent in [[archaea]]. Eukaryotes lack GCS, Pgb, and T3 subfamily globins.<ref name="pmid32863222"/> | ||
Eight globins are known to occur in vertebrates: | Eight globins are known to occur in vertebrates: androglobin (Adgb), [[cytoglobin]] (Cygb), globin E (GbE, from bird eye), globin X (GbX, not found in mammals or birds), globin Y (GbY, from some mammals), [[hemoglobin]] (Hb), [[myoglobin]] (Mb) and [[neuroglobin]] (Ngb).<ref name="pmid32863222"/> All these types evolved from a single globin gene of F/M family<ref name="pmid32863222"/> found in basal animals.<ref>{{cite journal |last1=Burmester |first1=T |last2=Hankeln |first2=T |title=Function and evolution of vertebrate globins. |journal=Acta Physiologica |date=July 2014 |volume=211 |issue=3 |pages=501–14 |doi=10.1111/apha.12312 |pmid=24811692|s2cid=33770617 |doi-access=free }}</ref> The single gene has also invented an oxygen-carrying "hemoglobin" multiple times in other groups of animals.<ref>Solène Song, Viktor Starunov, Xavier Bailly, Christine Ruta, Pierre Kerner, Annemiek J. M. Cornelissen, Guillaume Balavoine: [https://bmcevolbiol.biomedcentral.com/articles/10.1186/s12862-020-01714-4 Globins in the marine annelid Platynereis dumerilii shed new light on hemoglobin evolution in bilaterians]. In: BMC Evolutionary Biology Vol. 20, Issue 165. 29 December 2020. [[doi:10.1186/s12862-020-01714-4]]. See also: | ||
* [https://eurekalert.org/pub_releases/2020-12/c-asg122920.php A single gene 'invented' haemoglobin several times]. On: EurekAlert! 29 December 2020. Source: CNRS</ref> Several functionally different | * [https://eurekalert.org/pub_releases/2020-12/c-asg122920.php A single gene 'invented' haemoglobin several times]. On: EurekAlert! 29 December 2020. Source: CNRS</ref> Several functionally different hemoglobins can coexist in the same [[species]]. | ||
=== Sequence conservation === | === Sequence conservation === | ||
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==Subfamilies== | ==Subfamilies== | ||
*[[Leghaemoglobin]] {{InterPro|IPR001032}} | *[[Leghaemoglobin|Leghemoglobin]] {{InterPro|IPR001032}} | ||
*[[Myoglobin]] {{InterPro|IPR002335}} | *[[Myoglobin]] {{InterPro|IPR002335}} | ||
*[[Erythrocruorin]] {{InterPro|IPR002336}} | *[[Erythrocruorin]] {{InterPro|IPR002336}} | ||
*[[HBB|Hemoglobin, beta]] {{InterPro|IPR002337}} | *[[HBB|Hemoglobin, beta]] {{InterPro|IPR002337}} | ||
*[[HBA1|Hemoglobin, alpha]] {{InterPro|IPR002338}} | *[[HBA1|Hemoglobin, alpha]] {{InterPro|IPR002338}} | ||
* | *Myoglobin, trematode type {{InterPro|IPR011406}} | ||
* | *Globin, nematode {{InterPro|IPR012085}} | ||
* | *Globin, lamprey/hagfish type {{InterPro|IPR013314}} | ||
* | *Globin, annelid-type {{InterPro|IPR013316}} | ||
* | *Hemoglobin, extracellular {{InterPro|IPR014610}} | ||
== Examples == | == Examples == | ||
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Human genes encoding globin proteins include: | Human genes encoding globin proteins include: | ||
* [[Cytoglobin|CYGB]] | * [[Cytoglobin|CYGB]] | ||
* [[Hemoglobin, alpha 1|HBA1]], [[HBA2]], [[HBB]], [[HBD]], [[HBE1]], [[HBG1]], [[HBG2]], [[mu hemoglobin|HBM]], [[HBQ1]], [[Hemoglobin subunit zeta|HBZ]], [[myoglobin|MB]] | * [[Hemoglobin, alpha 1|HBA1]], [[HBA2]], [[HBB]], [[HBD (gene)|HBD]], [[HBE1]], [[HBG1]], [[HBG2]], [[mu hemoglobin|HBM]], [[HBQ1]], [[Hemoglobin subunit zeta|HBZ]], [[myoglobin|MB]] | ||
The globins include: | The globins include: | ||
*[[Haemoglobin]] (Hb) | *[[Haemoglobin|Hemoglobin]] (Hb) | ||
*[[Myoglobin]] (Mb) | *[[Myoglobin]] (Mb) | ||
* [[Neuroglobin]]: a myoglobin-like | * [[Neuroglobin]]: a myoglobin-like hemeprotein [[gene expression|expressed]] in vertebrate [[brain]] and retina, where it is involved in neuroprotection from damage due to [[Hypoxia (medical)|hypoxia]] or [[ischemia]].<ref name="pmid12962627">{{cite journal |vauthors=Pesce A, Dewilde S, Nardini M, Moens L, Ascenzi P, Hankeln T, Burmester T, Bolognesi M | title = Human brain neuroglobin structure reveals a distinct mode of controlling oxygen affinity | journal = Structure | volume = 11 | issue = 9 | pages = 1087–95 |date=September 2003 | pmid = 12962627 | doi = 10.1016/S0969-2126(03)00166-7| doi-access = free | hdl = 10067/455310151162165141 | hdl-access = free }}</ref> Neuroglobin belongs to a branch of the globin family that diverged early in [[evolution]]. | ||
*[[Cytoglobin]]: an oxygen sensor [[Gene expression|expressed]] in multiple [[Biological tissue|tissues]]. Related to neuroglobin.<ref name="pmid15804833">{{cite journal |vauthors=Fago A, Hundahl C, Malte H, Weber RE | title = Functional properties of neuroglobin and cytoglobin. Insights into the ancestral physiological roles of globins | journal = IUBMB Life | volume = 56 | issue = 11–12 | pages = 689–96 | year = 2004 | pmid = 15804833 | doi = 10.1080/15216540500037299 | s2cid = 21182182 | doi-access = free }}</ref> | *[[Cytoglobin]]: an oxygen sensor [[Gene expression|expressed]] in multiple [[Biological tissue|tissues]]. Related to neuroglobin.<ref name="pmid15804833">{{cite journal |vauthors=Fago A, Hundahl C, Malte H, Weber RE | title = Functional properties of neuroglobin and cytoglobin. Insights into the ancestral physiological roles of globins | journal = IUBMB Life | volume = 56 | issue = 11–12 | pages = 689–96 | year = 2004 | pmid = 15804833 | doi = 10.1080/15216540500037299 | s2cid = 21182182 | doi-access = free }}</ref> | ||
*[[Erythrocruorin]]: highly cooperative [[extracellular]] respiratory [[proteins]] found in [[annelid]]s and [[arthropod]]s that are assembled from as many as 180 subunit into hexagonal bilayers.<ref name="pmid17084861">{{cite journal |vauthors=Royer WE, Omartian MN, Knapp JE | title = Low resolution crystal structure of Arenicola erythrocruorin: influence of coiled coils on the architecture of a megadalton respiratory protein | journal = J. Mol. Biol. | volume = 365 | issue = 1 | pages = 226–36 |date=January 2007 | pmid = 17084861 | pmc = 1847385 | doi = 10.1016/j.jmb.2006.10.016 }}</ref> | *[[Erythrocruorin]]: highly cooperative [[extracellular]] respiratory [[proteins]] found in [[annelid]]s and [[arthropod]]s that are assembled from as many as 180 subunit into hexagonal bilayers.<ref name="pmid17084861">{{cite journal |vauthors=Royer WE, Omartian MN, Knapp JE | title = Low resolution crystal structure of Arenicola erythrocruorin: influence of coiled coils on the architecture of a megadalton respiratory protein | journal = J. Mol. Biol. | volume = 365 | issue = 1 | pages = 226–36 |date=January 2007 | pmid = 17084861 | pmc = 1847385 | doi = 10.1016/j.jmb.2006.10.016 }}</ref> | ||
*[[Leghaemoglobin]] (legHb or [[symbiosis|symbiotic]] Hb): occurs in the [[root nodule]]s of [[leguminous]] plants, where it facilitates the [[diffusion]] of oxygen to symbiotic bacteriods in order to promote [[nitrogen fixation]]. | *[[Leghaemoglobin|Leghemoglobin]] (legHb or [[symbiosis|symbiotic]] Hb): occurs in the [[root nodule]]s of [[leguminous]] plants, where it facilitates the [[diffusion]] of oxygen to symbiotic bacteriods in order to promote [[nitrogen fixation]]. | ||
* | *Non-symbiotic hemoglobin (NsHb): occurs in non-leguminous plants, and can be over-expressed in stressed [[plants]] . | ||
* | *Flavohemoglobins (FHb): chimeric, with an N-terminal globin domain and a C-terminal [[ferredoxin]] reductase-like NAD/FAD-binding domain. FHb provides protection against [[nitric oxide]] via its C-terminal domain, which transfers [[electron]]s to heme in the globin.<ref name="pmid11092893">{{cite journal |vauthors=Mukai M, Mills CE, Poole RK, Yeh SR | title = Flavohemoglobin, a globin with a peroxidase-like catalytic site | journal = J. Biol. Chem. | volume = 276 | issue = 10 | pages = 7272–7 |date=March 2001 | pmid = 11092893 | doi = 10.1074/jbc.M009280200 | doi-access = free }}</ref> | ||
*Globin E: a globin responsible for storing and delivering oxygen to the retina in birds<ref>{{cite journal |vauthors=Blank M, Kiger L, Thielebein A, Gerlach F, Hankeln T, Marden MC, Burmeister T |title= Oxygen supply from the bird's eye perspective: Globin E is a respiratory protein in the chicken retina |journal= J. Biol. Chem. |volume=286|issue=30|pages=26507–15|year=2011|pmid=21622558|doi= 10.1074/jbc.M111.224634|url=https://www.sciencedaily.com/releases/2011/06/110623130749.htm |pmc=3143615|doi-access= free }}</ref> | *Globin E: a globin responsible for storing and delivering oxygen to the retina in birds<ref>{{cite journal |vauthors=Blank M, Kiger L, Thielebein A, Gerlach F, Hankeln T, Marden MC, Burmeister T |title= Oxygen supply from the bird's eye perspective: Globin E is a respiratory protein in the chicken retina |journal= J. Biol. Chem. |volume=286|issue=30|pages=26507–15|year=2011|pmid=21622558|doi= 10.1074/jbc.M111.224634|url=https://www.sciencedaily.com/releases/2011/06/110623130749.htm |pmc=3143615|doi-access= free }}</ref> | ||
*Globin-coupled sensors: chimeric, with an N-terminal myoglobin-like domain and a C-terminal domain that resembles the [[cytoplasm]]ic [[cell signalling|signalling]] domain of [[bacteria]]l chemoreceptors. They [[molecular binding|bind]] oxygen, and act to initiate an aerotactic response or [[Transcriptional regulation|regulate]] [[gene expression]].<ref name="pmid11481493">{{cite journal |vauthors=Hou S, Freitas T, Larsen RW, Piatibratov M, Sivozhelezov V, Yamamoto A, Meleshkevitch EA, Zimmer M, Ordal GW, Alam M | title = Globin-coupled sensors: a class of heme-containing sensors in Archaea and Bacteria | journal = Proc. Natl. Acad. Sci. U.S.A. | volume = 98 | issue = 16 | pages = 9353–8 |date=July 2001 | pmid = 11481493 | pmc = 55424 | doi = 10.1073/pnas.161185598 | bibcode = 2001PNAS...98.9353H | doi-access = free }}</ref><ref name="pmid15598488">{{cite journal |vauthors=Freitas TA, Saito JA, Hou S, Alam M | title = Globin-coupled sensors, protoglobins, and the last universal common ancestor | journal = J. Inorg. Biochem. | volume = 99 | issue = 1 | pages = 23–33 |date=January 2005 | pmid = 15598488 | doi = 10.1016/j.jinorgbio.2004.10.024 }}</ref> | *Globin-coupled sensors: chimeric, with an N-terminal myoglobin-like domain and a C-terminal domain that resembles the [[cytoplasm]]ic [[cell signalling|signalling]] domain of [[bacteria]]l chemoreceptors. They [[molecular binding|bind]] oxygen, and act to initiate an aerotactic response or [[Transcriptional regulation|regulate]] [[gene expression]].<ref name="pmid11481493">{{cite journal |vauthors=Hou S, Freitas T, Larsen RW, Piatibratov M, Sivozhelezov V, Yamamoto A, Meleshkevitch EA, Zimmer M, Ordal GW, Alam M | title = Globin-coupled sensors: a class of heme-containing sensors in Archaea and Bacteria | journal = Proc. Natl. Acad. Sci. U.S.A. | volume = 98 | issue = 16 | pages = 9353–8 |date=July 2001 | pmid = 11481493 | pmc = 55424 | doi = 10.1073/pnas.161185598 | bibcode = 2001PNAS...98.9353H | doi-access = free }}</ref><ref name="pmid15598488">{{cite journal |vauthors=Freitas TA, Saito JA, Hou S, Alam M | title = Globin-coupled sensors, protoglobins, and the last universal common ancestor | journal = J. Inorg. Biochem. | volume = 99 | issue = 1 | pages = 23–33 |date=January 2005 | pmid = 15598488 | doi = 10.1016/j.jinorgbio.2004.10.024 }}</ref> | ||
* | *Protoglobin: a single domain globin found in [[archaea]] that is related to the N-terminal domain of globin-coupled sensors.<ref name="pmid15096613">{{cite journal |vauthors=Freitas TA, Hou S, Dioum EM, Saito JA, Newhouse J, Gonzalez G, Gilles-Gonzalez MA, Alam M | title = Ancestral hemoglobins in Archaea | journal = Proc. Natl. Acad. Sci. U.S.A. | volume = 101 | issue = 17 | pages = 6675–80 |date=April 2004 | pmid = 15096613 | pmc = 404104 | doi = 10.1073/pnas.0308657101 | bibcode = 2004PNAS..101.6675F | doi-access = free }}</ref> | ||
*Truncated 2/2 globin: lack the first helix, giving them a 2-over-2 instead of the canonical 3-over-3 [[alpha helix|alpha-helical]] sandwich [[protein folding|fold]]. Can be divided into three main groups (I, II and II) based on [[secondary structure|structural]] features. | *Truncated 2/2 globin: lack the first helix, giving them a 2-over-2 instead of the canonical 3-over-3 [[alpha helix|alpha-helical]] sandwich [[protein folding|fold]]. Can be divided into three main groups (I, II and II) based on [[secondary structure|structural]] features. | ||
*HbN (or GlbN): a truncated | *HbN (or GlbN): a truncated hemoglobin-like protein that binds oxygen cooperatively with a very high affinity and a slow [[Dissociation (chemistry)|dissociation]] rate, which may exclude it from oxygen transport. It appears to be involved in [[bacterial]] nitric oxide [[detoxification]] and in nitrosative [[Stress (medicine)|stress]].<ref name="pmid16814781">{{cite journal |vauthors=Lama A, Pawaria S, Dikshit KL | title = Oxygen binding and NO scavenging properties of truncated hemoglobin, HbN, of Mycobacterium smegmatis | journal = FEBS Lett. | volume = 580 | issue = 17 | pages = 4031–41 |date=July 2006 | pmid = 16814781 | doi = 10.1016/j.febslet.2006.06.037 | doi-access = free }}</ref> | ||
* | *Cyanoglobin (or GlbN): a truncated hemoprotein found in [[cyanobacteria]] that has high oxygen affinity, and which appears to serve as part of a terminal oxidase, rather than as a respiratory pigment.<ref name="pmid10684619">{{cite journal |vauthors=Yeh DC, Thorsteinsson MV, Bevan DR, Potts M, La Mar GN | title = Solution 1H NMR study of the heme cavity and folding topology of the abbreviated chain 118-residue globin from the cyanobacterium Nostoc commune | journal = Biochemistry | volume = 39 | issue = 6 | pages = 1389–99 |date=February 2000 | pmid = 10684619 | doi = 10.1021/bi992081l}}</ref> | ||
*HbO (or GlbO): a truncated | *HbO (or GlbO): a truncated hemoglobin-like protein with a lower oxygen affinity than HbN. HbO associates with the bacterial [[cell (biology)|cell]] membrane, where it [[statistical significance|significantly]] increases oxygen uptake over [[Cell membrane|membrane]]s lacking this protein. HbO appears to [[protein–protein interaction|interact]] with a terminal oxidase, and could participate in an oxygen/electron-transfer process that facilitates oxygen transfer during [[aerobic metabolism]].<ref name="pmid11796724">{{cite journal |vauthors=Pathania R, Navani NK, Rajamohan G, Dikshit KL | title = Mycobacterium tuberculosis hemoglobin HbO associates with membranes and stimulates cellular respiration of recombinant Escherichia coli | journal = J. Biol. Chem. | volume = 277 | issue = 18 | pages = 15293–302 |date=May 2002 | pmid = 11796724 | doi = 10.1074/jbc.M111478200 | doi-access = free }}</ref> | ||
*Glb3: a nuclear-encoded truncated | *Glb3: a nuclear-encoded truncated hemoglobin from [[plant]]s that appears more closely related to HbO than HbN. Glb3 from ''[[Arabidopsis thaliana]]'' (Mouse-ear cress) exhibits an unusual concentration-independent binding of oxygen and [[carbon dioxide]].<ref name="pmid11526234">{{cite journal |vauthors=Watts RA, Hunt PW, Hvitved AN, Hargrove MS, Peacock WJ, Dennis ES | title = A hemoglobin from plants homologous to truncated hemoglobins of microorganisms | journal = Proc. Natl. Acad. Sci. U.S.A. | volume = 98 | issue = 18 | pages = 10119–24 |date=August 2001 | pmid = 11526234 | pmc = 56925 | doi = 10.1073/pnas.191349198 | bibcode = 2001PNAS...9810119W | doi-access = free }}</ref> | ||
== The globin fold == | == The globin fold == | ||
The globin fold (cd01067) also includes some non- | The globin fold (cd01067) also includes some non-hem proteins. Some of them are the [[phycobiliprotein]]s, the N-terminal domain of [[two-component regulatory system]] [[histidine kinase]], ''RsbR'', and ''RsbN''. | ||
==See also== | ==See also== | ||
Latest revision as of 22:24, 11 October 2025
Template:Short description Script error: No such module "Distinguish".
Template:Infobox protein family Template:Infobox protein family Template:Infobox protein family The globins are a superfamily of heme-containing globular proteins, involved in binding and/or transporting oxygen. These proteins all incorporate the globin fold, a series of eight alpha helical segments. Two prominent members include myoglobin and hemoglobin. Both of these proteins reversibly bind oxygen via a heme prosthetic group. They are widely distributed in many organisms.[1]
Structure
Globin superfamily members share a common three-dimensional fold.[2] This 'globin fold' typically consists of eight alpha helices, although some proteins have additional helix extensions at their termini.[3] Since the globin fold contains only helices, it is classified as an all-alpha protein fold.
The globin fold is found in its namesake globin families as well as in phycocyanins. The globin fold was thus the first protein fold discovered (myoglobin was the first protein whose structure was solved).
Helix packaging
The eight helices of the globin fold core share significant nonlocal structure, unlike other structural motifs in which amino acids close to each other in primary sequence are also close in space. The helices pack together at an average angle of about 50 degrees, significantly steeper than other helical packings such as the helix bundle. The exact angle of helix packing depends on the sequence of the protein, because packing is mediated by the sterics and hydrophobic interactions of the amino acid side chains near the helix interfaces.
Evolution
Globins evolved from a common ancestor and can be divided into three lineages:[4][5]
- Family M (for myoglobin-like) or F (for FHb-like),[6] which has a typical 3/3 fold.
- Subfamily FHb, for flavohemoglobins. Chimeric.
- Subfamily SDgb, for single-domain globins (not to be confused with SSDgb).
- Family S (for sensor-like), again with a 3/3 fold.
- Subfamily GCS, for Globin-coupled sensors. Chimeric.
- Subfamily PGb, for protoglobins. Single-domain.
- Subfamily SSDgb, for sensor single-domain globins.
- Family T (for truncated), with a 2/2 fold[7] All subfamilies can be chimeric, single-domain, or tandemly linked.[6]
- Subfamily TrHb1 (also T1 or N).
- Subfamily TrHb2 (also T2 or O). Includes 2/2 phytoglobins.
- Subfamily TrHb3 (also T3 or P).
The M/F family of globins is absent in archaea. Eukaryotes lack GCS, Pgb, and T3 subfamily globins.[6]
Eight globins are known to occur in vertebrates: androglobin (Adgb), cytoglobin (Cygb), globin E (GbE, from bird eye), globin X (GbX, not found in mammals or birds), globin Y (GbY, from some mammals), hemoglobin (Hb), myoglobin (Mb) and neuroglobin (Ngb).[6] All these types evolved from a single globin gene of F/M family[6] found in basal animals.[8] The single gene has also invented an oxygen-carrying "hemoglobin" multiple times in other groups of animals.[9] Several functionally different hemoglobins can coexist in the same species.
Sequence conservation
Although the fold of the globin superfamily is highly evolutionarily conserved, the sequences that form the fold can have as low as 16% sequence identity. While the sequence specificity of the fold is not stringent, the hydrophobic core of the protein must be maintained and hydrophobic patches on the generally hydrophilic solvent-exposed surface must be avoided in order for the structure to remain stable and soluble. The most famous mutation in the globin fold is a change from glutamate to valine in one chain of the hemoglobin molecule. This mutation creates a "hydrophobic patch" on the protein surface that promotes intermolecular aggregation, the molecular event that gives rise to sickle-cell disease.Script error: No such module "Unsubst".
Subfamilies
- Leghemoglobin InterPro: IPR001032
- Myoglobin InterPro: IPR002335
- Erythrocruorin InterPro: IPR002336
- Hemoglobin, beta InterPro: IPR002337
- Hemoglobin, alpha InterPro: IPR002338
- Myoglobin, trematode type InterPro: IPR011406
- Globin, nematode InterPro: IPR012085
- Globin, lamprey/hagfish type InterPro: IPR013314
- Globin, annelid-type InterPro: IPR013316
- Hemoglobin, extracellular InterPro: IPR014610
Examples
Human genes encoding globin proteins include:
The globins include:
- Hemoglobin (Hb)
- Myoglobin (Mb)
- Neuroglobin: a myoglobin-like hemeprotein expressed in vertebrate brain and retina, where it is involved in neuroprotection from damage due to hypoxia or ischemia.[10] Neuroglobin belongs to a branch of the globin family that diverged early in evolution.
- Cytoglobin: an oxygen sensor expressed in multiple tissues. Related to neuroglobin.[11]
- Erythrocruorin: highly cooperative extracellular respiratory proteins found in annelids and arthropods that are assembled from as many as 180 subunit into hexagonal bilayers.[12]
- Leghemoglobin (legHb or symbiotic Hb): occurs in the root nodules of leguminous plants, where it facilitates the diffusion of oxygen to symbiotic bacteriods in order to promote nitrogen fixation.
- Non-symbiotic hemoglobin (NsHb): occurs in non-leguminous plants, and can be over-expressed in stressed plants .
- Flavohemoglobins (FHb): chimeric, with an N-terminal globin domain and a C-terminal ferredoxin reductase-like NAD/FAD-binding domain. FHb provides protection against nitric oxide via its C-terminal domain, which transfers electrons to heme in the globin.[13]
- Globin E: a globin responsible for storing and delivering oxygen to the retina in birds[14]
- Globin-coupled sensors: chimeric, with an N-terminal myoglobin-like domain and a C-terminal domain that resembles the cytoplasmic signalling domain of bacterial chemoreceptors. They bind oxygen, and act to initiate an aerotactic response or regulate gene expression.[15][16]
- Protoglobin: a single domain globin found in archaea that is related to the N-terminal domain of globin-coupled sensors.[17]
- Truncated 2/2 globin: lack the first helix, giving them a 2-over-2 instead of the canonical 3-over-3 alpha-helical sandwich fold. Can be divided into three main groups (I, II and II) based on structural features.
- HbN (or GlbN): a truncated hemoglobin-like protein that binds oxygen cooperatively with a very high affinity and a slow dissociation rate, which may exclude it from oxygen transport. It appears to be involved in bacterial nitric oxide detoxification and in nitrosative stress.[18]
- Cyanoglobin (or GlbN): a truncated hemoprotein found in cyanobacteria that has high oxygen affinity, and which appears to serve as part of a terminal oxidase, rather than as a respiratory pigment.[19]
- HbO (or GlbO): a truncated hemoglobin-like protein with a lower oxygen affinity than HbN. HbO associates with the bacterial cell membrane, where it significantly increases oxygen uptake over membranes lacking this protein. HbO appears to interact with a terminal oxidase, and could participate in an oxygen/electron-transfer process that facilitates oxygen transfer during aerobic metabolism.[20]
- Glb3: a nuclear-encoded truncated hemoglobin from plants that appears more closely related to HbO than HbN. Glb3 from Arabidopsis thaliana (Mouse-ear cress) exhibits an unusual concentration-independent binding of oxygen and carbon dioxide.[21]
The globin fold
The globin fold (cd01067) also includes some non-hem proteins. Some of them are the phycobiliproteins, the N-terminal domain of two-component regulatory system histidine kinase, RsbR, and RsbN.
See also
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References
Template:Globins Template:InterPro content
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- ↑ Solène Song, Viktor Starunov, Xavier Bailly, Christine Ruta, Pierre Kerner, Annemiek J. M. Cornelissen, Guillaume Balavoine: Globins in the marine annelid Platynereis dumerilii shed new light on hemoglobin evolution in bilaterians. In: BMC Evolutionary Biology Vol. 20, Issue 165. 29 December 2020. doi:10.1186/s12862-020-01714-4. See also:
- A single gene 'invented' haemoglobin several times. On: EurekAlert! 29 December 2020. Source: CNRS
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