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Mol Microbiol

Title:		Dominant-negative mutants of prgX: evidence for a role for PrgX dimerization in negative regulation of pheromone-inducible conjugation
Author(s):		Bae T; Dunny GM;
Address:		"Department of Microbiology, 1460 Mayo Memorial Bldg., University of Minnesota, Minneapolis 55455, USA"
Journal Title:		Mol Microbiol
Year:		2001
Volume:		39
Issue:		5
Page Number:		1307 - 1320
DOI:		10.1111/j.1365-2958.2001.02319.x
ISSN/ISBN:		0950-382X (Print) 0950-382X (Linking)
Abstract:		"PrgX negatively regulates prgQ transcriptional readthrough in the pheromone-inducible enterococcal conjugative plasmid pCF10. We isolated and characterized 13 dominant-negative prgX mutants, all of which mapped in either the N- or the C-terminus of PrgX. In all mutants, the in vivo level of Qa RNA, an antisense RNA to prgQ RNA, was greatly reduced. When oligomerization of PrgX was tested with a phage lambda cI repressor fusion system, the oligomerization domain was found to be between amino acid residues 78 and 280. When histidine-tagged PrgX (His-PrgX) was purified by nickel column chromatography from a strain also expressing PrgX, PrgX was co-purified with His-PrgX. Although PrgX was expressed at a much higher level than His-PrgX, an approximately equal amount of PrgX was co-purified. Pheromone induction greatly decreased the co-purification of PrgX. Based on these data, we propose that both the N- and the C-terminal domains of PrgX are required for PrgX positive autoregulation and for the repression of prgQ transcription readthrough. In vivo, PrgX exists as a dimer, and dimerization is mediated by the central region of PrgX"
Keywords:		"Amino Acid Sequence Bacterial Proteins/*genetics/metabolism Base Sequence *Conjugation, Genetic/drug effects Dimerization Enterococcus faecalis/*genetics/growth & development Gene Expression Regulation, Bacterial *Genes, Dominant Molecular Sequence Data *;"
Notes:		"MedlineBae, T Dunny, G M eng GM49530/GM/NIGMS NIH HHS/ Research Support, U.S. Gov't, P.H.S. England 2001/03/17 Mol Microbiol. 2001 Mar; 39(5):1307-20. doi: 10.1111/j.1365-2958.2001.02319.x"