Transfer of the plJ101 plasmid in Streptomyces lividans requires a cis-acting function dispensable for chromosomal gene transfer.
The tra gene of Streptomyces lividans plasmid plJ101 is required for both plasmid DNA transfer and plJ101-induced mobilization of chromosomal genes during mating. We show that a chromosomally inserted copy of tra mediates transfer of chromosomal DNA at high frequency but promotes efficient transfer of plasmids only when they contain a previously unknown locus, here named clt. Insertional mutation or deletion of clt from plJ101 reduced plasmid transfer mediated by either plasmid-borne or chromosomally located tra by at least three orders of magnitude, abolished the transfer-associated pocking phenomenon, and interfered with the ability of tra+ plasmids to promote transfer of chromosomal DNA. Our results indicate that plasmid transfer in S. lividans involves a cis-acting function dispensable for chromosomal gene transfer and imply that either the S. lividans chromosome encodes its own clt-like function or, alternatively, that transfer of plasmid and chromosomal DNA occurs by different mechanisms.
Department of Genetics, Stanford University School of Medicine, California 94305.
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D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D002876:Chromosomes, Bacterial; D003227:Conjugation, Genetic; D004269:DNA, Bacterial / Q000235:genetics*; D029968:Escherichia coli Proteins; D016254:Mutagenesis, Insertional; D010957:Plasmids / Q000235:genetics*; D012097:Repressor Proteins / Q000235:genetics / Q000502:physiology; D017384:Sequence Deletion; D013291:Streptococcus / Q000235:genetics*
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C090051:KorA protein, bacteria; D012097:Repressor Proteins; C067119:kilA protein, E coli