Extensive overproduction of the AdhE protein by rng mutations depends on mutations in the cra gene or in the Cra-box of the adhE promoter

Author： Kaga N. Umitsuki G. Clark D.P. Nagai K. Wachi M.

Publisher： Elsevier

ISSN： 0006-291X

Source： Biochemical and Biophysical Research Communications, Vol.295, Iss.1, 2002-07, pp. : 92-97

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Abstract

Escherichia coli RNase G encoded by therng gene is involved in degradation of adhE mRNA. Overproduction of the AdhE protein by rng mutants was found to depend on the genetic background of strains derived from DC272 (adhC81) or MC1061. We found that DC272 carried a point mutation in the Cra-binding site of the adhE promoter. The Cra protein encoded by the cra gene is known to act as a repressor of adhE. P1-phage-mediated transduction and lacZ fusion analysis with the mutant adhE promoter confirmed that this mutation is responsible for overproduction. On the other hand, Southern hybridization revealed that MC1061 had a 0.85-kb deletion of thecra gene. Overproduction of AdhE in the MC1061 background was reversed to the wild-type levels by introduction of a plasmid carrying thecra⁺ gene. These results indicated that expression of the adhE gene was regulated transcriptionally by Cra and posttranscriptionally by RNase G.© 2002 Elsevier Science (USA)