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Effect of the deletion of the σ32-dependent promoter (P1) of the Escherichia coli topoisomerase I gene on thermotolerance by Haiyan Qi; Rolf Menzel; Yuk-Ching Tse-Dinh is a Biochemistry, Genetics and Molecular Biology article available to read on EtoBox.

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Topoisomerase I and DNA gyrase are the major topoisomerase activities responsible for the regulation of DNA supercoiling in the bacterium __Escherichia coli__. The P1 promoter of __topA__ has previously been shown to be a σ^32^‐dependent heat‐shock promoter. A mutant strain with a deletion of P1 was constructed. This mutant is >10‐fold more sensitive to heat treatment (52°C) than the wild type. After brief treatment at 42°C, wild‐type __Escherichia coli__ acquires an enhanced resistance to the effects of a subsequent 52°C treatment. This is not the case for the P1 deletion mutant, which, and under these conditions, is about 100‐fold less thermotolerant than the wild type. The presence of a plasmid expressing topoisomerase I restored the heat‐survival level of the mutant to that of the wild type. During heat shock, the superhelical density of a plasmid with the heat‐inducible __rpoD__ promoter is increased in the P1 deletion mutant. We also note that the pulse‐labelling pattern of proteins at 42°C (displayed on SDS–polyacrylamide gels) is different in the mutant, and, most notably, the amounts of DnaK and of GroEL protein are reduced. A model is proposed in order to unify these obse

Who reads Effect of the deletion of the σ32-dependent promoter (P1) of the Escherichia coli topoisomerase I gene on thermotolerance?

Author

Haiyan Qi; Rolf Menzel; Yuk-Ching Tse-Dinh

Publisher

John Wiley and Sons; Wiley (Blackwell Publishing); Blackwell Publishing Inc.; Wiley (ISSN 0950-382X)

Published

1996

Language

EN

Field

Biochemistry, Genetics and Molecular Biology (Life Sciences)