VanE-type vancomycin-resistant Enterococcus faecalis clinical isolates from Australia

Abstract

Three distinct Enterococcus faecalis VanE-type isolates-BM4574, BM4575, and BM4576-obtained in Australia were studied. Expression of the resistance genes was constitutive in BM4575, probably due to a 2-bp deletion into the vanSE gene, and inducible in BM4574 and BM4576. Transcription analysis of the vanE operons suggested that the five genes were cotranscribed from an initiation site located 25 bp upstream from the ATG start codon of vanE.

FIG. 1.

Identification of the transcriptional start site by primer extension analysis. (Left) Primer elongation product obtained with oligodeoxynucleotide PE1 (1) and total RNA from BM4574 (lane 1), BM4575 (lane 2), and BM4576 (lane 3). Lanes T, G, C, and A show the results of sequencing reactions performed with the PE1 primer. The +1 transcriptional start site is indicated by an arrow. (Right) Sequence from nucleotide positions −81 to 12 (numbering from the A of the ATG start codon of vanE). The ribosome-binding site, the +1 transcriptional start site for the vanE, vanXY_E, vanT_E, vanR_E, and vanS_E mRNA, and the −35 and −10 promoter sequences located upstream are in boldface and are indicated. The ATG start codon of vanE is underlined.