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：1979
卷号：76
期号：4
页码：1702-1705
DOI：10.1073/pnas.76.4.1702
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：An Escherichia coli mutant, temperature-sensitive for DNA synthesis in vivo and in vitro, is defective in single-strand binding protein (SSB; DNA-binding protein). Conversion of phage G4 single strands to the duplex form is defective in crude enzyme fractions of the mutant and is complemented by pure wild-type SSB. Radioimmunoassays of mutant extracts show normal levels of material crossreacting with anti-SSB antibody. SSB purified to homogeneity from the mutant is active, with lower specific activity, in the reconstituted G4 replication assay at 30 degrees C, but virtually inactive at 42 degrees C. Surprisingly, the mutant protein, like the wild-type protein, survives heating at 100 degrees C. Thus, mutant SSB is structurally heat-resistant but is functionally thermosensitive in vitro and in vivo. Both the in vivo and in vitro defects are tightly linked in transductions by phage P1. The mutation in the binding protein, designated ssb-1, is located between 90 and 91 min on the E. coli genetic map.
