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J Bacteriol

Title:		"Characterization of comQ and comX, two genes required for production of ComX pheromone in Bacillus subtilis"
Author(s):		Bacon Schneider K; Palmer TM; Grossman AD;
Address:		"Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA"
Journal Title:		J Bacteriol
Year:		2002
Volume:		184
Issue:		2
Page Number:		410 - 419
DOI:		10.1128/JB.184.2.410-419.2002
ISSN/ISBN:		0021-9193 (Print) 1098-5530 (Electronic) 0021-9193 (Linking)
Abstract:		"Many microbes use secreted peptide-signaling molecules to stimulate changes in gene expression in response to high population density, a process called quorum sensing. ComX pheromone is a modified 10-amino-acid peptide used by Bacillus subtilis to modulate changes in gene expression in response to crowding. comQ and comX are required for production of ComX pheromone. We found that accumulation of ComX pheromone in culture supernatant paralleled cell growth, indicating that there was no autoinduction of production of ComX pheromone. We overexpressed comQ and comX separately and together and found that overexpression of comX alone was sufficient to cause an increase in production of ComX pheromone and early induction of a quorum-responsive promoter. These results indicate that the extracellular concentration of ComX pheromone plays a major role in determining the timing of the quorum response and that expression of comX is limiting for production of ComX pheromone. We made alanine substitutions in the residues that comprise the peptide backbone of ComX pheromone. Analysis of these mutants highlighted the importance of the modification for ComX pheromone function and identified three residues (T50, G54, and D55) that are unlikely to interact with proteins involved in production of or response to ComX pheromone. We have also identified and mutated a putative isoprenoid binding domain of ComQ. Mutations in this domain eliminated production of ComX pheromone, consistent with the hypothesis that ComQ is involved in modifying ComX pheromone and that the modification is likely to be an isoprenoid"
Keywords:		"Amino Acid Sequence Bacillus subtilis/*genetics/metabolism Bacterial Proteins/biosynthesis/*genetics/metabolism Culture Media Gene Expression Gene Expression Regulation, Bacterial Gene Expression Regulation, Enzymologic *Membrane Proteins Molecular Sequen;"
Notes:		"MedlineBacon Schneider, Katherine Palmer, Tanya M Grossman, Alan D eng R01 GM050895/GM/NIGMS NIH HHS/ GM50895/GM/NIGMS NIH HHS/ Research Support, U.S. Gov't, P.H.S. 2001/12/26 J Bacteriol. 2002 Jan; 184(2):410-9. doi: 10.1128/JB.184.2.410-419.2002"