Degradation of a Caulobacter soluble cytoplasmic chemoreceptor is ClpX dependent.
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.
Potocka
Isabel
I
Department of Biological Sciences, South Kensington Campus, Imperial College of Science, Technology and Medicine, London SW7 2AY, United Kingdom.
Thein
Melanie
M
ØSterås
Magne
M
Jenal
Urs
U
Alley
M R K
MR
D000074183:ATPases Associated with Diverse Cellular Activities; D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D016935:Caulobacter crescentus / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D002453:Cell Cycle; D002628:Chemoreceptor Cells / Q000378:metabolism*; D002633:Chemotaxis / Q000235:genetics; D003593:Cytoplasm; D049071:Endopeptidase Clp; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D000072236:Methyl-Accepting Chemotaxis Proteins; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D012995:Solubility
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; D018832:Molecular Chaperones; D049071:Endopeptidase Clp; D000251:Adenosine Triphosphatases; C088072:ClpX protein, E coli; D000074183:ATPases Associated with Diverse Cellular Activities