Degradation of a Caulobacter Soluble Cytoplasmic Chemoreceptor Is ClpX Dependent

Potocka, Isabel; Thein, Melanie; Østerås, Magne; Jenal, Urs; Alley, M. R. K.

doi:10.1128/jb.184.23.6635-6642.2002

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Journal article

Degradation of a Caulobacter Soluble Cytoplasmic Chemoreceptor Is ClpX Dependent

Potocka, Isabel Department of Biological Sciences, South Kensington Campus, Imperial College of Science, Technology and Medicine, London SW7 2AY, United Kingdom
Thein, Melanie Department of Biological Sciences, South Kensington Campus, Imperial College of Science, Technology and Medicine, London SW7 2AY, United Kingdom
Østerås, Magne Division of Molecular Microbiology, Biozentrum, University of Basel, CH-4056 Basel, Switzerland
Jenal, Urs Division of Molecular Microbiology, Biozentrum, University of Basel, CH-4056 Basel, Switzerland
Alley, M. R. K. Department of Biological Sciences, South Kensington Campus, Imperial College of Science, Technology and Medicine, London SW7 2AY, United Kingdom

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Journal of Bacteriology. - American Society for Microbiology. - 2002, vol. 184, no. 23, p. 6635-6641

English ABSTRACT
In order to determine whether ClpXP-mediated proteolysis is a common mechanism used to regulate the chemotaxis machinery during the cell cycle of Caulobacter crescentus, we have characterized a soluble cytoplasmic chemoreceptor, McpB. The mcpB gene lies adjacent to the major chemotaxis operon, which encodes 12 chemotaxis proteins, including the membrane chemoreceptor McpA. Like McpA, McpB possesses a C-terminal CheBR docking motif and three potential methylation sites, which we suggest are methylated. The McpB protein is degraded via a ClpX-dependent pathway during the swarmer-to-stalked cell transition, and a motif, which is 3 amino acids N-terminal to the McpB CheBR docking site, is required for proteolysis. Analysis of the degradation signal in McpB and McpA reveals a common motif present in the other four chemoreceptors that possess CheBR docking sites. A green fluorescent protein (GFP) fusion bearing 58 amino acids from the C terminus of McpA, which contains this motif, is degraded, suggesting that the C-terminal sequence is sufficient to confer ClpXP protease susceptibility.

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