| Title: | "Pheromone-regulated expression of sex pheromone plasmid pAD1-encoded aggregation substance depends on at least six upstream genes and a cis-acting, orientation-dependent factor" |
| Address: | "Universitat Regensburg, NWFIII-Mikrobiologie, D-93053 Regensburg, Germany. albrecht.muscholl@biologie.uni-regensburg.de" |
| DOI: | 10.1128/JB.182.13.3816-3825.2000 |
| ISSN/ISBN: | 0021-9193 (Print) 1098-5530 (Electronic) 0021-9193 (Linking) |
| Abstract: | "Conjugative transfer of Enterococcus faecalis-specific sex pheromone plasmids relies on an adhesin, called aggregation substance, to confer a tight cell-to-cell contact between the mating partners. To analyze the dependence of pAD1-encoded aggregation substance, Asa1, on pheromone induction, a variety of upstream fragments were fused to an alpha-amylase reporter gene, amyL, by use of a novel promoter probe vector, pAMY-em1. For pheromone-regulated alpha-amylase activity, a total of at least six genes, traB, traC, traA, traE1, orfY, and orf1, are required: TraB efficiently represses asa1 (by a mechanism unrelated to its presumptive function in pheromone shutdown, since a complete shutdown is observed exclusively in the presence of traC); only traC can relieve traB-mediated repression in a pheromone-dependent manner. In addition to traB, traA is required but not sufficient for negative control. Mutational inactivation of traE1, orfY, or orf1, respectively, results in a total loss of alpha-amylase activity for constructs normally mediating constitutive expression. Inversion of a fragment covering traA, P(0), and traE1 without disrupting any gene or control element switches off amyL or asa1 expression, indicating the involvement of a cis-acting, orientation-dependent factor (as had been shown for plasmid pCF10). Unexpectedly, pAD1 represses all pAMY-em1 derivatives in trans, while its own pheromone-dependent functions are unaffected. The discrepancy between the new data and those of former studies defining TraE1 as a trans-acting positive regulator is discussed" |
| Keywords: | "Adhesins, Bacterial/*genetics Bacterial Proteins/*genetics/metabolism Enterococcus faecalis/*genetics Fimbriae Proteins *Gene Expression Regulation, Bacterial Genes, Bacterial Genetic Vectors Membrane Proteins/genetics/metabolism Molecular Sequence Data P;" |
| Notes: | "MedlineMuscholl-Silberhorn, A B eng 2000/06/13 J Bacteriol. 2000 Jul; 182(13):3816-25. doi: 10.1128/JB.182.13.3816-3825.2000" |
