Saravanan Matheshwaran, Vasu Kommireddy, Nagaraja Valakunja
Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India.
Proc Natl Acad Sci U S A. 2008 Jul 29;105(30):10344-7. doi: 10.1073/pnas.0804974105. Epub 2008 Jul 22.
Restriction endonucleases (REases) protect bacteria from invading foreign DNAs and are endowed with exquisite sequence specificity. REases have originated from the ancestral proteins and evolved new sequence specificities by genetic recombination, gene duplication, replication slippage, and transpositional events. They are also speculated to have evolved from nonspecific endonucleases, attaining a high degree of sequence specificity through point mutations. We describe here an example of generation of exquisitely site-specific REase from a highly-promiscuous one by a single point mutation.
限制性内切酶（REases）保护细菌免受外来DNA的入侵，并具有极高的序列特异性。REases起源于祖先蛋白，并通过基因重组、基因复制、复制滑移和转座事件进化出新的序列特异性。也有人推测它们是从非特异性内切酶进化而来，通过点突变获得高度的序列特异性。我们在此描述了一个通过单点突变从高度混杂的REase产生极其位点特异性REase的例子。
