Robinson C R, Sligar S G
Department of Biochemistry, University of Illinois at Urbana-Champaign 61801.
J Mol Biol. 1993 Nov 20;234(2):302-6. doi: 10.1006/jmbi.1993.1586.
Many restriction endonucleases such as EcoRI lose some specificity for their recognition sequence under certain buffer conditions. The cause of this disruption of accurate protein-DNA recognition has never been explained. By cleaving DNA with EcoRI in the presence of several osmolytes, we show that the extent of this EcoRI "star activity" depends strongly upon osmotic pressure. The loss of specificity accompanying decreased water activity implies a role for one or more water molecules in recognition of specific sequences of DNA. Water mediation may constitute a general motif for sequence-specific DNA recognition by restriction enzymes and other DNA-binding proteins.
许多限制性内切核酸酶，如EcoRI，在某些缓冲液条件下会对其识别序列失去一些特异性。这种精确的蛋白质-DNA识别破坏的原因从未得到解释。通过在几种渗透溶质存在的情况下用EcoRI切割DNA，我们发现这种EcoRI“星号活性”的程度强烈依赖于渗透压。随着水活性降低而出现的特异性丧失意味着一个或多个水分子在识别DNA特定序列中发挥作用。水介导可能构成限制酶和其他DNA结合蛋白进行序列特异性DNA识别的一个普遍模式。
