PMID:10825179

Citation	Zimmer, MA, Tiu, J, Collins, MA and Ordal, GW (2000) Selective methylation changes on the Bacillus subtilis chemotaxis receptor McpB promote adaptation. J. Biol. Chem. 275:24264-72
Abstract	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 the Escherichia coli consensus sequence. To explore the nature of methanol release from a class III receptor, all combinations of putative methylation sites Gln(371), Gln(595), Glu(630), and Glu(637) were substituted with aspartate, a conservative substitution that effectively eliminates methylation. McpB((Q371D,E630D,E637D)) in a Delta(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. coli and 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.
Links	PubMed Online version:10.1074/jbc.M004001200
Keywords	Amino Acid Sequence; Amino Acid Substitution; Asparagine/metabolism; Bacillus subtilis/genetics; Bacillus subtilis/physiology; Bacterial Proteins/chemistry; Bacterial Proteins/genetics; Bacterial Proteins/physiology; Chemoreceptor Cells/physiology; Consensus Sequence; Genotype; Glutamic Acid; Glutamine; Membrane Proteins; Methanol/metabolism; Methylation; Models, Biological; Mutagenesis, Site-Directed; Recombinant Proteins/chemistry; Recombinant Proteins/metabolism; Static Electricity
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
BACSU:MCPB		GO:0004888: transmembrane signaling receptor activity	ECO:0000315:		F		See 'Effect of Double Aspartate Substitutions on Methanol Release' and 'Behavioral Effects…' sections, as demonstrated in Figure 6.	complete CACAO 10505
BACSU:MCPB		GO:0006935: chemotaxis	ECO:0000315:		P		See Figure 2.	complete CACAO 10506

References

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