期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1974
卷号：71
期号：9
页码：3593-3597
DOI：10.1073/pnas.71.9.3593
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：recB and/or recC deficiency in Escherichia coli K-12 is indirectly suppressed by the presence of sbcA- mutations. sbcA- strains contain an increased level of an ATP-independent nuclease. Genetic and enzymatic tests indicate that this activity is not exonuclease III, exonuclease V (recB-recC nuclease), DNA polymerase I, or lambda exonuclease. This new enzyme (exonuclease VIII) has been purified 750-fold and shows a striking preference for double-stranded DNA over heat-denatured DNA. It does not act endonucleolytically on closed circular, single-stranded DNA as exonuclease V does. It also lacks a 3'-phosphatase function. Analysis on sodium dodecyl sulfate-polyacrylamide gels indicates that exonuclease VIII is not present in unsuppressed (sbcA+) strains. It is thought that sbcA determines some type of control function; the structural gene for exonuclease VIII is denoted by recE.
关键词：genetic recombination ; Escherichia coli ; recB ; exonuclease V
