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Characterization of Escherichia coli Flagellar Mutants That Are Insensitive to Catabolite Repression

Silverman, Michael and Simon, Melvin (1974) Characterization of Escherichia coli Flagellar Mutants That Are Insensitive to Catabolite Repression. Journal of Bacteriology, 120 (3). pp. 1196-1203. ISSN 0021-9193. PMCID PMC245899.

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In Escherichia coli, the synthesis of the flagellar organelle is sensitive to catabolite repression. Synthesis requires the presence of the cyclic adenosine monophosphate receptor protein (Crp) and 3′,5′-cyclic adenosine monophosphate (cAMP); i.e., mutants that lack Crp or adenylcyclase (Cya) synthesize no flagella. We isolated and characterized a series of mutants (cfs) that restored flagella-forming ability in a Crp strain of E. coli. The mutations in these strains were transferred onto episomes and they were then introduced into a variety of other strains. The presence of the mutation resulted in flagella synthesis in Cya and Crp strains as well as in the wild type grown under conditions of catabolite repression. Deletion analysis and other genetic studies indicated that: (i) the cfs mutations had a dominant effect when they were in the transconfiguration in merodiploids: (ii) they occurred in or very close to the flaI gene: and (iii) their expression required the presence of an intact flaI gene adjacent to the cfs mutation. Biochemical studies showed that the synthesis of at least two flagellar polypeptides, the hook subunit and an amber fragment of flagellin, were absent in strains that carried a cya mutation. Their synthesis was depressed in strains grown under conditions of catabolite repression. The presence of the cfs mutation restored the specific synthesis of these two polypeptides. We suggest that the formation of the flaI gene product is the step in flagellar synthesis that is catabolite sensitive and requires cAMP. We propose a regulatory function for the product of the flaI gene.

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Additional Information:© 1974 American Society for Microbiology. Received for publication 16 September 1974. We wish to express our appreciation to Laura Hofstadter, Marcia Hilmen, and Judy Jessup for their assistance with this project. M. Silverman was supported by funds from the Cancer Coordinating Committee of the University of California, San Diego. This investigation was supported by a research grant GB-15655 from the National Science Foundation.
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University of California San DiegoUNSPECIFIED
Issue or Number:3
PubMed Central ID:PMC245899
Record Number:CaltechAUTHORS:20120813-161928632
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Official Citation:Characterization of Escherichia coli Flagellar Mutants That are Insensitive to Catabolite Repression Michael Silverman and Melvin Simon J. Bacteriol. December 1974 120:1196-1203
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:33143
Deposited On:14 Aug 2012 14:59
Last Modified:03 Oct 2019 04:07

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