中文摘要：

目的明确从国内分离的尿道致病性大肠杆菌（UPEC）132中发现的新基因R049的特征及其表达蛋白在菌体内的定位。方法提取UPEC132染色体DNA，鸟枪法构建文库，高通量焦磷酸法测序，Newbler软件拼接，进行生物信息学分析，确定R049相关片段的特征。提取UPEC132的内膜和外膜蛋白，与其全菌裂解物一起进行SDS-PAGE，用R049重组蛋白抗血清进行Westernblot，确定R049表达蛋白的菌体内位置。结果成功构建UPEC132染色体文库，获取R049-contig169022bp，与UPEC536染色体第233074至451502位碱基序列同源性较高，其中含有R049基因的20773bp片段替代相当于UPEC536染色体上PAIⅢ536的位置，G＋C含量为46，97％，两端具有正向重复序列，并与插入元件整合酶基因和thrWtRNA基因相邻，包含25个ORF，命名为R049-GI。R049基因位于R049．GI的第13个ORF。SDS—PAGE和Westernblot分析显示R049基因表达相对分子质量为47．0×10^3蛋白是UPEC132的外膜蛋白。结论R049基因编码细菌的外膜蛋白，是UPEC132通过基因水平转移获得的染色体基因组岛的组成部分。

英文摘要：

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. Methods The chro- mosome 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. Results The 169 022 bp contig containing gene R049 was ob- tained 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 PA111I 53s 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 RO49-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. Conclusion Gene R049, encoding an outer membrane protein, was a component part of the genome island in UPEC 132 chromosome acquired by horizontal gene transfer.