Selective Methylation Changes on the Bacillus subtilis Chemotaxis Receptor McpB Promote Adaptation

The Bacillus subtilis McpB is a class III chemotaxis receptor, from which methanol is released in response to all stimuli. McpB has four putative methylation sites based upon theEscherichia coli consensus sequence. To explore the nature of methanol release from a class III receptor, all combinations...

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Bibliographic Details
Published in:	The Journal of biological chemistry Vol. 275; no. 32; pp. 24264 - 24272
Main Authors:	Zimmer, Michael A., Tiu, Joseph, Collins, Marissa A., Ordal, George W.
Format:	Journal Article
Language:	English
Published:	United States Elsevier Inc 11-08-2000 American Society for Biochemistry and Molecular Biology
Subjects:	Amino Acid Sequence Amino Acid Substitution asparagine Asparagine - metabolism Bacillus subtilis Bacillus subtilis - genetics Bacillus subtilis - physiology Bacterial Proteins - chemistry Bacterial Proteins - genetics Bacterial Proteins - physiology CheC protein Chemoreceptor Cells - physiology chemotaxis receptors Consensus Sequence Escherichia coli Genotype Glutamic Acid Glutamine McpB protein Membrane Proteins methanol Methanol - metabolism Methylation Models, Biological Mutagenesis, Site-Directed Recombinant Proteins - chemistry Recombinant Proteins - metabolism Static Electricity
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Summary:	The Bacillus subtilis McpB is a class III chemotaxis receptor, from which methanol is released in response to all stimuli. McpB has four putative methylation sites based upon theEscherichia coli consensus sequence. To explore the nature of methanol release from a class III receptor, all combinations of putative methylation sites Gln371, Gln595, Glu630, and Glu637 were substituted with aspartate, a conservative substitution that effectively eliminates methylation. McpB(Q371D,E630D,E637D) in a Δ(mcpA mcpB tlpA tlpB)101::cat mcpC4::erm background failed to release methanol in response to either the addition or removal of the McpB-mediated attractant asparagine. In the same background, McpB(E630D,E637D) produced methanol only upon asparagine addition, whereas McpB(Q371D,E630D) produced methanol only upon asparagine removal. Thus methanol release from McpB was selective. Mutants unable to methylate site 637 but able to methylate site 630 had high prestimulus biases and were incapable of adapting to asparagine addition. Mutants unable to methylate site 630 but able to methylate site 637 had low prestimulus biases and were impaired in adaptation to asparagine removal. We propose that selective methylation of these two sites represents a method of adaptation novel from E. coliand present a model in which a charged residue rests between them. The placement of this charge would allow for opposing electrostatic effects (and hence opposing receptor conformational changes). We propose that CheC, a protein not found in enteric systems, has a role in regulating this selective methylation.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23
ISSN:	0021-9258 1083-351X
DOI:	10.1074/jbc.M004001200