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Gene Review

prgB  -  aggregation substance

Enterococcus faecalis

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Disease relevance of prgB


High impact information on prgB

  • Previous transposon mutagenesis and sequencing analysis of a 12-kilobase (kb) region of pCF10 indicated that several genes including prgR and prgS are required to activate expression of prgB [2].
  • However, when the regulatory region and target genes were cloned in different sites of the same plasmid, separated by as much as 12 kb, activation of prgB was observed [2].
  • To test this, a promoterless lacZ gene fusion to prgB was constructed and cloned without some or all of the regulatory genes [2].
  • Neither production of this peptide nor translation of the 5' end of prgQ transcripts was found to be necessary for prgB expression [3].
  • Q(L) is present in ribosomes translating the prgB message, and pheromone cCF10 may affect the association of this RNA with translation complexes [4].

Chemical compound and disease context of prgB


Biological context of prgB

  • Remarkably, aggregation substance (Asc10, encoded by the prgB gene) was present on the cell surface for a long period of time after pheromone-induced transcription of prgB and plasmid transfer ability had ceased [5].
  • The prgB gene encodes the surface protein Asc10, which mediates cell aggregation resulting in high-frequency conjugative transfer of the pheromone-inducible tetracycline resistance plasmid pCF10 in Enterococcus faecalis [6].
  • Previous Tn5 insertional mutagenesis and sequencing analysis of a 12-kb fragment of pCF10 indicated that a region containing prgX, -Q, -R, -S, and -T, located 3 to 6 kb upstream of prgB, is required to activate the expression of prgB [6].
  • A model for transcriptional activation of prgB is presented [7].
  • The lack of any other open reading frame in QL RNA and significant sequence complementarity between the 3' end of QL RNA and the promoter region of prgB suggested that the functional products of the prgQ region might be RNA molecules rather than proteins [7].

Other interactions of prgB

  • The genes mapped include prgA (encoding Sec10) and prgB (encoding Asc10), as well as four putative regulatory genes, prgX, -R, -S, and -T [8].
  • The results indicate that prgQ and -S are required for the expression of prgB, while prgX, -R, and -T are not required [6].

Analytical, diagnostic and therapeutic context of prgB

  • Messenger RNA analysis by Northern blot hybridization and primer extension indicates that prgB transcription is pheromone-inducible and monocistronic [2].
  • The prgB gene, which encodes aggregation substance, was detected in all the clinical isolates and transconjugants by both PCR and DNA hybridization but prgA, which encodes the surface exclusion protein, was only detected in two isolates, whereas it is present in most pheromone response plasmids from other sources [9].
  • Western blot (immunoblot) analysis of these mutants shows that prgQ is also essential for the expression of prgA (encoding the surface exclusion protein Sec10), which is located between prgB and the positive-control region [6].


  1. Identification and characterization of the genes of Enterococcus faecalis plasmid pCF10 involved in replication and in negative control of pheromone-inducible conjugation. Hedberg, P.J., Leonard, B.A., Ruhfel, R.E., Dunny, G.M. Plasmid (1996) [Pubmed]
  2. Cis-acting, orientation-dependent, positive control system activates pheromone-inducible conjugation functions at distances greater than 10 kilobases upstream from its target in Enterococcus faecalis. Chung, J.W., Dunny, G.M. Proc. Natl. Acad. Sci. U.S.A. (1992) [Pubmed]
  3. Pheromone cCF10 and plasmid pCF10-encoded regulatory molecules act post-transcriptionally to activate expression of downstream conjugation functions. Bensing, B.A., Manias, D.A., Dunny, G.M. Mol. Microbiol. (1997) [Pubmed]
  4. Pheromone-inducible expression of an aggregation protein in Enterococcus faecalis requires interaction of a plasmid-encoded RNA with components of the ribosome. Bensing, B.A., Dunny, G.M. Mol. Microbiol. (1997) [Pubmed]
  5. Characterization of the pheromone response of the Enterococcus faecalis conjugative plasmid pCF10: complete sequence and comparative analysis of the transcriptional and phenotypic responses of pCF10-containing cells to pheromone induction. Hirt, H., Manias, D.A., Bryan, E.M., Klein, J.R., Marklund, J.K., Staddon, J.H., Paustian, M.L., Kapur, V., Dunny, G.M. J. Bacteriol. (2005) [Pubmed]
  6. Genetic analysis of a region of the Enterococcus faecalis plasmid pCF10 involved in positive regulation of conjugative transfer functions. Chung, J.W., Bensing, B.A., Dunny, G.M. J. Bacteriol. (1995) [Pubmed]
  7. Transcriptional analysis of a region of the Enterococcus faecalis plasmid pCF10 involved in positive regulation of conjugative transfer functions. Chung, J.W., Dunny, G.M. J. Bacteriol. (1995) [Pubmed]
  8. Molecular and genetic analysis of a region of plasmid pCF10 containing positive control genes and structural genes encoding surface proteins involved in pheromone-inducible conjugation in Enterococcus faecalis. Kao, S.M., Olmsted, S.B., Viksnins, A.S., Gallo, J.C., Dunny, G.M. J. Bacteriol. (1991) [Pubmed]
  9. Pheromone responses and high-level aminoglycoside resistance of conjugative plasmids of Enterococcus faecalis from Greece. Pournaras, S., Tsakris, A., Palepou, M.F., Papa, A., Douboyas, J., Antoniadis, A., Woodford, N. J. Antimicrob. Chemother. (2000) [Pubmed]
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