Hydrogen hypothesis: Difference between revisions
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The '''hydrogen hypothesis''' is a model proposed by [[William F. Martin]] and Miklós Müller in 1998 that describes a possible way in which the [[mitochondrion]] arose as an [[endosymbiont]] within a |
The '''hydrogen hypothesis''' is a model proposed by [[William F. Martin]] and Miklós Müller in 1998 that describes a possible way in which the [[mitochondrion]] arose as an [[endosymbiont]] within a prokaryotic host in the [[archaea]], giving rise to a [[symbiosis|symbiotic]] association of two cells from which the first [[Eukaryote|eukaryotic cell]] could have arisen ([[symbiogenesis]]). |
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According to the hydrogen hypothesis: |
According to the hydrogen hypothesis:<ref name=EmbleyMartin/><ref name=Lane2005/><ref name=LopezMoreira/><ref name=MartinMuller/><ref name=PoolePenny/> |
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* The |
* The hosts that acquired the mitochondria were [[hydrogen]]-dependent [[archaea]], possibly similar in physiology to modern [[methanogenic]] archaea, which use hydrogen and [[carbon dioxide]] to produce [[methane]]; |
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* The future mitochondrion was a [[Facultative anaerobic|facultatively anaerobic]] [[Eubacteria|eubacterium]] which produced hydrogen and carbon dioxide as byproducts of [[anaerobic respiration]]; |
* The future mitochondrion was a [[Facultative anaerobic|facultatively anaerobic]] [[Eubacteria|eubacterium]] which produced hydrogen and carbon dioxide as byproducts of [[anaerobic respiration]]; |
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* A symbiotic relationship between the two started, based on the host's hydrogen dependence (anaerobic [[syntrophy]]). |
* A symbiotic relationship between the two started, based on the host's hydrogen dependence (anaerobic [[syntrophy]]). |
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==Mechanism== |
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| ⚫ | The hypothesis differs from many alternative views within the [[endosymbiotic theory]] framework, which suggest that the first eukaryotic [[Cell (biology)|cells]] evolved a nucleus but lacked mitochondria, the latter arising as a eukaryote engulfed a primitive [[bacterium]] that eventually became the mitochondrion. The hypothesis attaches [[evolution]]ary significance to [[hydrogenosome]]s and provides a rationale for their common ancestry with mitochondria. Hydrogenosomes are anaerobic mitochondria that produce [[adenosine triphosphate|ATP]] by, as a rule, converting [[pyruvate]] into hydrogen, carbon dioxide and [[acetate]]. Examples from modern biology are known where methanogens cluster around hydrogenosomes within eukaryotic cells. Most theories within the [[endosymbiotic theory]] framework do not address the common ancestry of mitochondria and hydrogenosomes. The hypothesis provides a straightforward explanation for the observation that eukaryotes are genetic [[Chimera (genetics)|chimeras]] with genes of archaeal and eubacterial ancestry. Furthermore, it would imply that archaea and eukarya split after the modern groups of archaea appeared. Most theories within the [[endosymbiotic theory]] framework predict that some eukaryotes never possessed mitochondria. The hydrogen hypothesis predicts that no primitively mitochondrion-lacking eukaryotes ever existed. In the 15 years following the publication of the hydrogen hypothesis, this specific prediction has been tested many times and found to be in agreement with observation.<ref>{{cite journal | author=Embley TM and Martin W | title=Eukaryotic evolution, changes and challenges | journal=Nature | year=2006 | volume=440 | pages=623–630 | doi=10.1038/nature04546 | pmid=16572163 | issue=7084}}</ref><ref>{{cite book |author=Lane, Nick |authorlink=Nick Lane |title= |
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| ⚫ | The hypothesis differs from many alternative views within the [[endosymbiotic theory]] framework, which suggest that the first eukaryotic [[Cell (biology)|cells]] evolved a nucleus but lacked mitochondria, the latter arising as a eukaryote engulfed a primitive [[bacterium]] that eventually became the mitochondrion. The hypothesis attaches [[evolution]]ary significance to [[hydrogenosome]]s and provides a rationale for their common ancestry with mitochondria. Hydrogenosomes are anaerobic mitochondria that produce [[adenosine triphosphate|ATP]] by, as a rule, converting [[pyruvate]] into hydrogen, carbon dioxide and [[acetate]]. Examples from modern biology are known where methanogens cluster around hydrogenosomes within eukaryotic cells. Most theories within the [[endosymbiotic theory]] framework do not address the common ancestry of mitochondria and hydrogenosomes. The hypothesis provides a straightforward explanation for the observation that eukaryotes are genetic [[Chimera (genetics)|chimeras]] with genes of archaeal and eubacterial ancestry. Furthermore, it would imply that archaea and eukarya split after the modern groups of archaea appeared. Most theories within the [[endosymbiotic theory]] framework predict that some eukaryotes never possessed mitochondria. The hydrogen hypothesis predicts that no primitively mitochondrion-lacking eukaryotes ever existed. In the 15 years following the publication of the hydrogen hypothesis, this specific prediction has been tested many times and found to be in agreement with observation.<ref name=EmbleyMartin>{{cite journal | author=Embley TM and Martin W | title=Eukaryotic evolution, changes and challenges | journal=Nature | year=2006 | volume=440 | pages=623–630 | doi=10.1038/nature04546 | pmid=16572163 | issue=7084| bibcode=2006Natur.440..623E | s2cid=4396543 | url=https://zenodo.org/record/897869 }}</ref><ref name=Lane2005>{{cite book |author=Lane, Nick |authorlink=Nick Lane |title=Power, Sex, Suicide: Mitochondria and the Meaning of Life |year=2005 |publisher=Oxford University Press |isbn=978-0-19-920564-6|title-link=Power, Sex, Suicide: Mitochondria and the Meaning of Life }}</ref><ref name=LopezMoreira>{{cite journal |author=López-Garćia P and Moreira D | title=Metabolic symbiosis at the origin of eukaryotes | journal=Trends Biochem Sci | year=1999 | volume=24 | pages=88–93 | issue=3 | doi=10.1016/S0968-0004(98)01342-5 | pmid=10203753}}</ref><ref name=MartinMuller>{{cite journal | author=Martin W and Müller M | title=The hydrogen hypothesis for the first eukaryote | journal=Nature | year=1998 | volume=392 | pages=37–41 | issue=6671 | doi=10.1038/32096 | pmid=9510246| bibcode=1998Natur.392...37M | s2cid=338885 }}</ref><ref name=PoolePenny>{{cite journal | author=Poole AM and Penny D | title=Evaluating hypotheses for the origin of eukaryotes | journal=BioEssays | year=2007 | volume=29 | pages=74–84 | issue=1 | doi=10.1002/bies.20516 | pmid=17187354}}</ref> |
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| ⚫ | In 2015, the discovery and placement of the [[Lokiarchaeota]] (an archaeal lineage possessing an expanded genetic repertoire including genes involved in membrane remodeling and actin cytoskeletal structure) as the sister group to eukaryotes called into question particular tenets of the hydrogen hypothesis, as Lokiarchaeota appear to lack methanogenesis.<ref name="SpangSaw2015">{{cite journal |last1=Spang |first1=Anja |last2=Saw |first2=Jimmy H. |last3=Jørgensen |first3=Steffen L. |last4=Zaremba-Niedzwiedzka |first4=Katarzyna |last5=Martijn |first5=Joran |last6=Lind |first6=Anders E.|last7=van Eijk |first7=Roel |last8=Schleper|first8=Christa |last9=Guy |first9=Lionel |last10=Ettema |first10=Thijs J. G. |title=Complex archaea that bridge the gap between prokaryotes and eukaryotes |journal=Nature |year=2015 |doi=10.1038/nature14447 |volume=521 |pages=173–179 |pmid=25945739 |pmc=4444528}}</ref> |
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| ⚫ | In 2015, the discovery and placement of the [[Lokiarchaeota]] (an archaeal lineage possessing an expanded genetic repertoire including genes involved in membrane remodeling and [[actin]] cytoskeletal structure) as the sister group to eukaryotes called into question particular tenets of the hydrogen hypothesis, as Lokiarchaeota appear to lack methanogenesis.<ref name="SpangSaw2015">{{cite journal |last1=Spang |first1=Anja |last2=Saw |first2=Jimmy H. |last3=Jørgensen |first3=Steffen L. |last4=Zaremba-Niedzwiedzka |first4=Katarzyna |last5=Martijn |first5=Joran |last6=Lind |first6=Anders E.|last7=van Eijk |first7=Roel |last8=Schleper|first8=Christa |last9=Guy |first9=Lionel |last10=Ettema |first10=Thijs J. G. |title=Complex archaea that bridge the gap between prokaryotes and eukaryotes |journal=Nature |year=2015 |doi=10.1038/nature14447 |volume=521 |issue=7551 |pages=173–179 |pmid=25945739 |pmc=4444528|bibcode=2015Natur.521..173S }}</ref> |
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==See also== |
==See also== |
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*[[Archezoa]] |
*[[Archezoa]] |
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*[[ |
*[[Eocyte hypothesis]] |
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*[[William F. Martin]] |
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==References== |
==References== |
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Latest revision as of 03:12, 29 October 2024
The hydrogen hypothesis is a model proposed by William F. Martin and Miklós Müller in 1998 that describes a possible way in which the mitochondrion arose as an endosymbiont within a prokaryotic host in the archaea, giving rise to a symbiotic association of two cells from which the first eukaryotic cell could have arisen (symbiogenesis).
According to the hydrogen hypothesis:[1][2][3][4][5]
- The hosts that acquired the mitochondria were hydrogen-dependent archaea, possibly similar in physiology to modern methanogenic archaea, which use hydrogen and carbon dioxide to produce methane;
- The future mitochondrion was a facultatively anaerobic eubacterium which produced hydrogen and carbon dioxide as byproducts of anaerobic respiration;
- A symbiotic relationship between the two started, based on the host's hydrogen dependence (anaerobic syntrophy).
Mechanism
[edit]The hypothesis differs from many alternative views within the endosymbiotic theory framework, which suggest that the first eukaryotic cells evolved a nucleus but lacked mitochondria, the latter arising as a eukaryote engulfed a primitive bacterium that eventually became the mitochondrion. The hypothesis attaches evolutionary significance to hydrogenosomes and provides a rationale for their common ancestry with mitochondria. Hydrogenosomes are anaerobic mitochondria that produce ATP by, as a rule, converting pyruvate into hydrogen, carbon dioxide and acetate. Examples from modern biology are known where methanogens cluster around hydrogenosomes within eukaryotic cells. Most theories within the endosymbiotic theory framework do not address the common ancestry of mitochondria and hydrogenosomes. The hypothesis provides a straightforward explanation for the observation that eukaryotes are genetic chimeras with genes of archaeal and eubacterial ancestry. Furthermore, it would imply that archaea and eukarya split after the modern groups of archaea appeared. Most theories within the endosymbiotic theory framework predict that some eukaryotes never possessed mitochondria. The hydrogen hypothesis predicts that no primitively mitochondrion-lacking eukaryotes ever existed. In the 15 years following the publication of the hydrogen hypothesis, this specific prediction has been tested many times and found to be in agreement with observation.[1][2][3][4][5]
In 2015, the discovery and placement of the Lokiarchaeota (an archaeal lineage possessing an expanded genetic repertoire including genes involved in membrane remodeling and actin cytoskeletal structure) as the sister group to eukaryotes called into question particular tenets of the hydrogen hypothesis, as Lokiarchaeota appear to lack methanogenesis.[6]
See also
[edit]References
[edit]- ^ a b Embley TM and Martin W (2006). "Eukaryotic evolution, changes and challenges". Nature. 440 (7084): 623–630. Bibcode:2006Natur.440..623E. doi:10.1038/nature04546. PMID 16572163. S2CID 4396543.
- ^ a b Lane, Nick (2005). Power, Sex, Suicide: Mitochondria and the Meaning of Life. Oxford University Press. ISBN 978-0-19-920564-6.
- ^ a b López-Garćia P and Moreira D (1999). "Metabolic symbiosis at the origin of eukaryotes". Trends Biochem Sci. 24 (3): 88–93. doi:10.1016/S0968-0004(98)01342-5. PMID 10203753.
- ^ a b Martin W and Müller M (1998). "The hydrogen hypothesis for the first eukaryote". Nature. 392 (6671): 37–41. Bibcode:1998Natur.392...37M. doi:10.1038/32096. PMID 9510246. S2CID 338885.
- ^ a b Poole AM and Penny D (2007). "Evaluating hypotheses for the origin of eukaryotes". BioEssays. 29 (1): 74–84. doi:10.1002/bies.20516. PMID 17187354.
- ^ Spang, Anja; Saw, Jimmy H.; Jørgensen, Steffen L.; Zaremba-Niedzwiedzka, Katarzyna; Martijn, Joran; Lind, Anders E.; van Eijk, Roel; Schleper, Christa; Guy, Lionel; Ettema, Thijs J. G. (2015). "Complex archaea that bridge the gap between prokaryotes and eukaryotes". Nature. 521 (7551): 173–179. Bibcode:2015Natur.521..173S. doi:10.1038/nature14447. PMC 4444528. PMID 25945739.