Repeat sequences limit the effectiveness of lateral gene transfer and favored the evolution of meiotic sex in early eukaryotes.
Repeat sequences limit the effectiveness of lateral gene transfer and favored the evolution of meiotic sex in early eukaryotes.
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DOI：
10.1073/pnas.2205041119
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发表时间：
2022-08-30
影响因子：
11.1
通讯作者：
中科院分区：
文献类型：
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减数分裂性的起源是一个长期存在的进化谜。这种新的生殖机制取代了横向基因转移（LGT），即在细菌和古细菌中看到的环境DNA片段的摄取和重组。我们将其起源与早期真核生物中发现的扩大的基因组大小和遗传重复序列的增殖联系起来。这两个因素都导致了LGT下的高水平突变积累和基因丢失，这不能通过增加LGT率或DNA重组长度来延缓。与长染色体大小的DNA片段同源配对的减数分裂性促进了纯化选择，抑制了异位重组。它允许复杂的真核生物进化所需的扩展基因组的进化。从原核生物的横向基因转移到真核生物减数分裂性别的转变尚不清楚。系统发育证据表明，它与真核发生密切相关，真核发生涉及基因组大小和基因重复密度的前所未有的增加。基因组大小的扩大提高了穆勒棘轮的严重程度，同时限制了横向基因转移（LGT）清除有害突变的有效性。原则上，增加重组长度和提高LGT速率可以解决这个问题。在这里，我们使用计算模型表明，这种解决方案在早期真核生物中普遍存在的遗传重复中失败。该模型表明，分散的重复序列允许异位重组，这导致遗传信息的丢失，并削弱了LGT防止突变积累的能力。在重复序列存在的情况下，增加重组长度加剧了这个问题。突变衰变只能通过DNA扩展序列的同源性来抵抗。我们得出结论，向沿线性染色体的同源配对过渡是减数分裂性别的一个关键创新，这有助于真核生物基因组的扩展和形态复杂性。
The origin of meiotic sex is a long-standing evolutionary enigma. This novel mechanism of reproduction replaced lateral gene transfer (LGT), the uptake and recombination of pieces of environmental DNA seen in bacteria and archaea. We link its origin to the expanded genome size and proliferation of genetic repeats found in early eukaryotes. Both factors led to high levels of mutation accumulation and gene loss under LGT, which could not be retarded through increases in the rate of LGT or the length of DNA recombined. Meiotic sex with homologous pairing of long-chromosome-sized pieces of DNA promoted purifying selection and suppressed ectopic recombination. It permitted the evolution of the expanded genome needed for the evolution of complex eukaryotic life. The transition from prokaryotic lateral gene transfer to eukaryotic meiotic sex is poorly understood. Phylogenetic evidence suggests that it was tightly linked to eukaryogenesis, which involved an unprecedented rise in both genome size and the density of genetic repeats. Expansion of genome size raised the severity of Muller’s ratchet, while limiting the effectiveness of lateral gene transfer (LGT) at purging deleterious mutations. In principle, an increase in recombination length combined with higher rates of LGT could solve this problem. Here, we show using a computational model that this solution fails in the presence of genetic repeats prevalent in early eukaryotes. The model demonstrates that dispersed repeat sequences allow ectopic recombination, which leads to the loss of genetic information and curtails the capacity of LGT to prevent mutation accumulation. Increasing recombination length in the presence of repeat sequences exacerbates the problem. Mutational decay can only be resisted with homology along extended sequences of DNA. We conclude that the transition to homologous pairing along linear chromosomes was a key innovation in meiotic sex, which was instrumental in the expansion of eukaryotic genomes and morphological complexity.
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DOI：
10.1073/pnas.042263399
发表时间：
2002-02-19
影响因子：
11.1
作者：
de Vries, J;Wackernagel, W
通讯作者：
Wackernagel, W
影响因子：
64.8
作者：
KONDRASHOV, AS
通讯作者：
KONDRASHOV, AS
影响因子：
6.7
作者：
Croucher, Nicholas J.;Harris, Simon R.;Bentley, Stephen D.
通讯作者：
Bentley, Stephen D.
影响因子：
6.7
作者：
Engelmoer DJ;Donaldson I;Rozen DE
通讯作者：
Rozen DE
影响因子：
3.3
作者：
Baltrus, David A.;Guillemin, Karen;Phillips, Patrick C.
通讯作者：
Phillips, Patrick C.