Characterization of a novel gene R049 in uropathogenic Escherichia coli / 中华微生物学和免疫学杂志

ABSTRACT

Objective To investigate the character and location of a novel gene R049 and its expressed protein in uropathogenic Escherichia coli(UPEC) strain 132 isolated in China. MethodsThe chromosome library of UPEC132 was constructed by a shotgun strategy and the sequence analysis was carried out by a high-throughput pyrophosphate sequencing. Sequence reads were assembled with the Newbler program.The characters of R049-associated specific fragment were analyzed using the bioinformatics methods. Outer and inner membrane proteins of UPEC132 were extracted and then detected by SDS-PAGE and Western blot analysis together with the whole-cell lysates. ResultsThe 169 022 bp contig containing gene R049 was obtained and its sequence was very similar to the chromosome associated sequence of UPEC strain 536. It showed that a 20 773 bp fragment including R049 replaced the pathogenicity island PAI Ⅲ536 of UPEC536 in above 169 022 bp contig. The fragment had a lower GC content (46.97％) and 16 bp direct repeats in two ends. Significantly it also was adjacented to thrW tRNA, insertion element and genes coding integrase. Thus the 20 773 bp fragment was named R049 genome island(R049-GI). There were 25 ORFs in R049-GI, and gene R049 was located in the thirteenth ORF. The results of SDS-PAGE and Western blot revealed gene R049 encoded an outer membrane protein in the size of 47.0× 103. ConclusionGene R049, encoding an outer membrane protein, was a component part of the genome island in UPEC 132 chromosome acquired by horizontal gene transfer.