RecBCD enzyme and Chi recombination hotspots as determinants of self vs. non-self: Myths and mechanisms.
RecBCD enzyme and Chi recombination hotspots as determinants of self vs. non-self: Myths and mechanisms.
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DOI：
10.1016/bs.adgen.2022.06.001
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发表时间：
2022
影响因子：
--
通讯作者：
Smith, Gerald R
中科院分区：
文献类型：
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作者：
Subramaniam, Suriyen;Smith, Gerald R
当DNA通过转化、交配或噬菌体感染进入细菌细胞时，细菌面临着挑战。他们是应该把这种DNA当作外来入侵生物来对待并摧毁它，还是应该把它视为自己的一部分，并通过整合新的基因或等位基因来获得有用的功能而潜在地受益？通常认为，短核苷酸序列CHI(5‘GCTGGTGG3’)是由大肠杆菌的RecBCD解旋酶核酸酶识别的同源基因重组的热点，它允许大肠杆菌将其DNA(SELF)与任何其他DNA(非SELE)区分开来，并破坏非SELE DNA，CHI在大肠杆菌基因组中“过度代表”。我们在这里表明，这些说法没有得到现有证据的支持。我们注意到CHI在远亲细菌物种和噬菌体中广泛存在和活动。我们说明了大肠杆菌和噬菌体P1基因组的多个高度非随机特征，这些特征解释了CHI的高频和基因组位置，导致我们提出P1选择CHI促进重组，而大肠杆菌选择CHI中首选的密码子。我们讨论了之前描述的涉及RecBCD的自我决定与非自我决定的其他机制，以及RecBCD破坏不能重组的DNA的机制，无论是国外的还是国内的，无论有没有CHI。
Bacteria face a challenge when DNA enters their cells by transformation, mating, or phage infection. Should they treat this DNA as an invasive foreigner and destroy it, or consider it one of their own and potentially benefit from incorporating new genes or alleles to gain useful functions? It is frequently stated that the short nucleotide sequence Chi (5' GCTGGTGG 3'), a hotspot of homologous genetic recombination recognized by Escherichia coli's RecBCD helicase-nuclease, allows E. coli to distinguish its DNA (self) from any other DNA (non-self) and to destroy non-self DNA, and that Chi is “over-represented” in the E. coli genome. We show here that these statements are not supported by available evidence. We note Chi's wide-spread occurrence and activity in distantly related bacterial species and phages. We illustrate multiple, highly non-random features of the genomes of E. coli and coliphage P1 that account for Chi’s high frequency and genomic position, leading us to propose that P1 selects for Chi's enhancement of recombination, whereas E. coli selects for the preferred codons in Chi. We discuss other, previously described mechanisms for self vs. non-self determination involving RecBCD and for RecBCD’s destruction of DNA that cannot recombine, whether foreign or domestic, with or without Chi.