Eder P S, Walder R Y, Walder J A
Department of Biochemistry, University of Iowa, Iowa City 52242.
Biochimie. 1993;75(1-2):123-6. doi: 10.1016/0300-9084(93)90033-o.
Recently we have shown that the major isoform of RNase H in human cells, RNase H1, is able to cleave DNA substrates containing a single RNA-DNA base pair, an activity which appears to be involved in an excision repair system for the removal of ribose residues misincorporated into DNA. In the present work we have further characterized the substrate specificity of the enzyme. DNA substrates containing all four ribonucleotides are cleaved by the enzyme. A RNA-DNA base pair is not required for substrate recognition. RNA residues present within a mismatch or in a RNA-RNA base pair are also cleaved. The principal structural feature for recognition by the enzyme may simply be the presence of the 2'-OH group of the ribose residue adjacent to the cleavage site.
最近我们发现，人类细胞中核糖核酸酶H（RNase H）的主要同工型RNase H1能够切割含有单个RNA-DNA碱基对的DNA底物，这种活性似乎参与了一种切除修复系统，用于去除错误掺入DNA中的核糖残基。在本研究中，我们进一步对该酶的底物特异性进行了表征。该酶能够切割含有所有四种核糖核苷酸的DNA底物。底物识别并不需要RNA-DNA碱基对。错配或RNA-RNA碱基对中的RNA残基也能被切割。该酶识别的主要结构特征可能仅仅是切割位点相邻核糖残基的2'-OH基团的存在。
