RT Journal Article SR Electronic(1) A1 Morgan, Roderick M. A1 Macrina, Francis L.YR 1997 T1 bctA: a novel pBF4 gene necessary for conjugal transfer in Bacteroides spp. JF Microbiology, VO 143 IS 7 SP 2155 OP 2165 DO https://doi.org/10.1099/00221287-143-7-2155 PB Microbiology Society, SN 1465-2080, AB Summary: pBF4 is a 41 kb conjugative R-plasmid that confers MLS (macrolide-lincosamide-streptogramin B) resistance in Bacteroides spp. To identify pBF4 genes governing conjugation, recombinational mutagenesis using a suicide vector carrying fragments of the pBF4 plasmid was employed. One of six independent insertion mutants of pBF4 isolated using this method was found to be conjugation-deficient. Nucleotide sequence analysis around the insertion site on this plasmid revealed a 2.8 kb ORF that encoded a putative 110 kDa protein. A corresponding protein was observed when a 12 kb DNA fragment containing this ORF was used to program an in vitro transcription-translation system. Both the ORF and the predicted protein were novel when compared to available database sequences. This gene was designated bctA (Bacteroides conjugal transfer). Polyclonal rabbit antibodies that recognized a sub-sequence polypeptide of BctA reacted with a 55 kDa protein in Western blot analysis using a total protein extract from Bacteroides fragilis containing pBF4. The protein was not present in a B. fragilis strain containing the conjugation-deficient insertion mutant of pBF4. The 55 kDa protein was associated with the membrane fraction of B. fragilis. Although the cellular and biochemical basis of bctA-promoted conjugation remains unknown, this work demonstrates the existence of a heretofore unrecognized gene in bacterial conjugation, and the mutagenesis system used provides the means to isolate and characterize other genes involved in conjugal transfer in Bacteroides spp., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-143-7-2155