Dominant-negative mutants of prgX: Evidence for a role for PrgX dimerization in negative regulation of pheromone-inducible conjugation

T. Bae, G. M. Dunny

Research output: Contribution to journalArticle

19 Scopus citations

Abstract

PrgX negatively regulates prgQ transcriptional read-through 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 cl 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 read-through. In vivo, PrgX exists as a dimer, and dimerization is mediated by the central region of PrgX.

Original languageEnglish (US)
Pages (from-to)1307-1320
Number of pages14
JournalMolecular Microbiology
Volume39
Issue number5
DOIs
StatePublished - Mar 31 2001
Externally publishedYes

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology

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