Identification of a region that influences host range of the streptococcal conjugative plasmid pIP501.
pIP501 is a member of a group of conjugative plasmids that are self-transmissible to a wide variety of streptococci as well as to other gram-positive bacteria. Several pIP501 restriction fragment deletion derivatives have been isolated and characterized. In this paper we describe one such derivative (pVA1702) which was conjugally proficient but had a limited host range. The loss of host range ability was seen as decreased conjugal transfer from Enterococcus faecalis to Streptococcus sanguis and was coincident with the deletion of a 4.5-kb DNA fragment. Transformation of pVA1702 into S. sanguis also was dramatically reduced as compared to its progenitor, suggesting the 4.5-kb fragment encoded a factor(s) necessary for stable maintenance in this host but not in E. faecalis. These observations suggest that pIP501 employs specific mechanisms enabling its maintenance in certain gram-positive bacteria.
Krah
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Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond 23298-0678.
Macrina
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FL
D002872:Chromosome Deletion; D003227:Conjugation, Genetic; D013293:Enterococcus faecalis / Q000235:genetics; D010957:Plasmids / Q000235:genetics*; D015183:Restriction Mapping; D013298:Streptococcus sanguis / Q000235:genetics*