Mutational analysis of the tra locus of the broad-host-range Streptomyces plasmid pIJ101.
The tra gene of Streptomyces lividans plasmid pIJ101 encodes a 621-amino-acid protein that can mediate both plasmid transfer and the interbacterial transfer of chromosomal genes (i.e., chromosome-mobilizing ability [Cma]) during mating. Here we report the results of in-frame insertional mutagenesis studies aimed at defining regions of Tra required for these functions. While hexameric linker insertions throughout the tra gene affected plasmid and chromosomal gene transfer, insertions in a 200-amino-acid region of the Tra protein that contains presumed nucleotide-binding motifs and that is widely conserved among a functionally diverse family of bacterial and plasmid proteins (K. J. Begg, S. J. Dewar, and W. D. Donachie, J. Bacteriol. 177:6211-6222, 1995) had especially prominent effects on both functions. Insertions near the N terminus of Tra reduced Cma for either circular or linear host chromosomes to a much greater extent than pIJ101 plasmid transfer. Our results suggest that Cma involves Tra functions incremental to those needed for plasmid DNA transfer.
Pettis
G S
GS
Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, USA. gpettis@unixl.sncc.lsu.edu
Cohen
S N
SN
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D002876:Chromosomes, Bacterial / Q000235:genetics; D004252:DNA Mutational Analysis; D018014:Gene Transfer Techniques; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D010957:Plasmids / Q000235:genetics*; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013302:Streptomyces / Q000235:genetics*
D001426:Bacterial Proteins; D011994:Recombinant Proteins; C085510:transfer region protein, Staphylococcus