Excision of thymine dimers by proteolytic and amber fragments of E. coli DNA polymerase I |
| |
Authors: | E C Friedberg I R Lehman |
| |
Institution: | 3. Laboratory of Experimental Oncology Department of Pathology Stanford University School of Medicine Stanford, California 94305 USA;1. Department of Biochemistry Stanford University School of Medicine Stanford, California 94305 USA |
| |
Abstract: | Excision of thymine dimers from specifically incised ultraviolet irradiated DNA by DNA polymerase I is stimulated by concurrent DNA synthesis. The 36,000 molecular-weight “small fragment” obtained by limited proteolysis of DNA polymerase I, which retains only the 5′ → 3′ exonuclease activity, also excises thymine dimers, but at one-tenth the rate of the intact enzyme. However, the rate of excision is increased by addition of the “large” 76,000-molecular weight fragment. With the further addition of the 4 deoxynucleoside triphosphates, permitting DNA synthesis to occur, excision approaches rates observed with the intact enzyme. The same result was obtained with a fragment of DNA polymerase I with 5′ → 3′ exonuclease activity that is present uniquely in polymerase I mutants. |
| |
Keywords: | |
本文献已被 ScienceDirect 等数据库收录! |
|