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J Bacteriol

Title:		Phase variation of Enterococcus faecalis pAD1 conjugation functions relates to changes in iteron sequence region
Author(s):		Heath DG; An FY; Weaver KE; Clewell DB;
Address:		"Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor 48109, USA"
Journal Title:		J Bacteriol
Year:		1995
Volume:		177
Issue:		19
Page Number:		5453 - 5459
DOI:		10.1128/jb.177.19.5453-5459.1995
ISSN/ISBN:		0021-9193 (Print) 1098-5530 (Electronic) 0021-9193 (Linking)
Abstract:		"pAD1 (60 kb) is a conjugative, hemolysin/bacteriocin plasmid in Enterococcus faecalis. It confers a mating response to the peptide sex pheromone cAD1 produced by recipient (plasmid-free) cells, leading to highly efficient plasmid transfer in broth matings. Control of the physiological response to cAD1 can been overridden by a reversible phase variation event at frequencies on the order of 10(-4) to 10(-3) per cell per generation (L. T. Pontius and D. B. Clewell, Plasmid 26:172-185, 1991). The variant forms are designated Dryc and Dry+, which reflects the colony morphologies of cells whose conjugation functions are switched on and off, respectively. Here we show that Dryc variants exhibit a structural change in a region between repA and repB that contains two clusters of 8-bp iterons. The change involved a 31- or 32-bp increase in size of this region. In three or four independent variants examined, one of the iteron clusters increased in size from 13 to 17 iterons. When iteron DNA was placed on a multicopy plasmid and introduced into a wild-type pAD1 derivative, the Dryc phenotype was generated. Since traA, a key negative regulator of conjugation, bears several centrally located iteron-like sequences with the same orientation, we speculate that the protein(s) that normally binds iterons (possibly RepA and/or RepB) blocks traA transcription in Dryc variants"
Keywords:		"Bacterial Proteins/genetics Base Sequence Conjugation, Genetic/*genetics *DNA Helicases *DNA-Binding Proteins Enterococcus faecalis/*genetics/physiology *Fimbriae Proteins Genes, Bacterial/genetics Molecular Sequence Data Plasmids/*genetics *Proteins Repe;"
Notes:		"MedlineHeath, D G An, F Y Weaver, K E Clewell, D B eng GM33956/GM/NIGMS NIH HHS/ GM47587/GM/NIGMS NIH HHS/ Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. Research Support, U.S. Gov't, P.H.S. 1995/10/01 J Bacteriol. 1995 Oct; 177(19):5453-9. doi: 10.1128/jb.177.19.5453-5459.1995"