PT  - JOURNAL ARTICLE
AU  - Jiaohao Gu
AU  - Xiaojun Wang
AU  - Xiaopan Ma
AU  - Ying Sun
AU  - Xiang Xiao
AU  - Haiwei Luo
TI  - Unexpectedly high mutation rate of a deep-sea hyperthermophilic anaerobic archaeon
AID  - 10.1101/2020.09.09.287623
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.09.09.287623
4099  - http://biorxiv.org/content/early/2020/09/09/2020.09.09.287623.short
4100  - http://biorxiv.org/content/early/2020/09/09/2020.09.09.287623.full
AB  - Deep sea hydrothermal vents resemble the early Earth 1, and thus the dominant Thermococcaceae inhabitants, which occupy an evolutionarily basal position of the archaeal tree 2,3 and take an obligate anaerobic hyperthermophilic free-living lifestyle 4, are likely excellent models to study the evolution of early life. Here, we determined that unbiased mutation rate of a representative species, Thermococcus eurythermalis 5, exceeded that of all known free-living prokaryotes by 1-2 orders of magnitude, and thus rejected the long-standing hypothesis that low mutation rates were selectively favored in hyperthermophiles 6–8. We further sequenced multiple and diverse isolates of this species and calculated that T. eurythermalis has a lower effective population size than other free-living prokaryotes by 1-2 orders of magnitude. These data are well explained by the “drift-barrier” model 9, indicating that the high mutation rate of this species is not selectively favored but instead driven by random genetic drift. The availability of these unusual data has far-reaching implications for prokaryote genome evolution. For example, a synthesis of additional 29 species with unbiased mutation rate data across bacteria and archaea enabled us to conclude that genome reduction across prokaryotes is universally driven by increased mutation rate and random genetic drift. Taken together, exceptionally high mutation rate and low effective population size likely feature the early life in hot and anoxic marine habitats, which are indispensable in synthesizing the universal rule of genome evolution across prokaryotes and the Earth history.Competing Interest StatementThe authors have declared no competing interest.