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Mol Microbiol

Title:		Enterococcus faecalis pheromone-responsive protein PrgX: genetic separation of positive autoregulatory functions from those involved in negative regulation of conjugative plasmid transfer
Author(s):		Kozlowicz BK; Bae T; Dunny GM;
Address:		"Department of Microbiology, 1460 Mayo Memorial Bldg., University of Minnesota, MN 55455, USA"
Journal Title:		Mol Microbiol
Year:		2004
Volume:		54
Issue:		2
Page Number:		520 - 532
DOI:		10.1111/j.1365-2958.2004.04286.x
ISSN/ISBN:		0950-382X (Print) 0950-382X (Linking)
Abstract:		"The pCF10 plasmid in Enterococcus faecalis transfers from donor cells to recipients upon induction via peptide pheromone. Two plasmid-encoded negative regulators produced from the same transcript, PrgX protein and Qa RNA, repress conjugation genes in uninduced donor cells. PrgX positively autoregulates production of both itself and mature Qa RNA, and is believed to repress the prgQ promoter in a pheromone-sensitive fashion. Previous analysis of PrgX was complicated because mutations in prgX affecting regulation of conjugation also disrupted PrgX autoregulation, suggesting the two functions might be inseparable. In this study, we isolated 14 single amino acid substitutions in PrgX that reduced or eliminated repression of prgQ, without affecting autoregulation or DNA binding. PrgX was shown to bind to its cognate pheromone, cCF10, and most of the mutations lowered the affinity of PrgX for cCF10. Dimerization was affected by five of the mutations and the data indicate that it is required, but insufficient for pheromone induction. We propose a new model for the mechanism used by PrgX for regulation of the prgQ promoter, PrgX autoregulation, and Qa RNA processing"
Keywords:		"Bacterial Proteins/chemistry/genetics/*metabolism *Conjugation, Genetic Dimerization Enterococcus faecalis/genetics/*metabolism *Gene Expression Regulation, Bacterial Genes, Reporter Oligopeptides/genetics/*metabolism Peptides/metabolism Phenotype Pheromo;"
Notes:		"MedlineKozlowicz, Briana K Bae, Taeok Dunny, Gary M eng GM49530/GM/NIGMS NIH HHS/ T32 GM08347/GM/NIGMS NIH HHS/ Research Support, U.S. Gov't, P.H.S. England 2004/10/08 Mol Microbiol. 2004 Oct; 54(2):520-32. doi: 10.1111/j.1365-2958.2004.04286.x"