Swaminathan N, Mead D A, McMaster K, George D, Van Etten J L, Skowron P M
CHIMERx, Madison, WI 53704, USA.
Nucleic Acids Res. 1996 Jul 1;24(13):2463-9. doi: 10.1093/nar/24.13.2463.
R.CviJI is unique among site-specific restriction endonucleases in that its activity can be modulated to recognize either a two or three base sequence. Normally R.CviJI cleaves RGCY sites between the G and C to leave blunt ends. In the presence of ATP R.CviJI* cleaves RGCN and YGCY sites, but not YGCR sites. The gene encoding R.CviJI was cloned from the eukaryotic Chlorella virus IL-3A and expressed in Escherichia coli. The primary E.coli cviJIR gene product is a 278 amino acid protein initiated from a GTG codon, rather than the expected 358 amino acid protein initiated from an in-frame upstream ATG codon. Interestingly, the 278 amino acid protein displays the normal restriction activity but not the R.CviJI* activity of the native enzyme. Nine restriction and modification proteins which recognize a central GC or CG sequence share short regions of identity with R.CviJI amino acids 144-235, suggesting that this region is the recognition and/or catalytic domain.
R.CviJI在位点特异性限制内切核酸酶中是独特的，因为其活性可以被调节以识别二碱基或三碱基序列。正常情况下，R.CviJI在G和C之间切割RGCY位点，产生平端。在ATP存在的情况下，R.CviJI切割RGCN和YGCY位点，但不切割YGCR位点。编码R.CviJI的基因从真核小球藻病毒IL-3A中克隆出来，并在大肠杆菌中表达。大肠杆菌cviJIR基因的初级产物是一个由GTG密码子起始的278个氨基酸的蛋白质，而不是预期的由框内上游ATG密码子起始的358个氨基酸的蛋白质。有趣的是，这个278个氨基酸的蛋白质表现出正常的限制活性，但不具有天然酶的R.CviJI活性。九种识别中央GC或CG序列的限制和修饰蛋白与R.CviJI的144-235位氨基酸有短的同源区域，表明该区域是识别和/或催化结构域。
