Xu Y, Singh K V, Qin X, Murray B E, Weinstock G M
Department of Microbiology and Molecular Genetics, University of Texas Medical School, Houston, Texas 77030, USA.
Infect Immun. 2000 Feb;68(2):815-23. doi: 10.1128/IAI.68.2.815-823.2000.
Previously, we described a gene cluster of Enterococcus faecalis OG1RF that produced an antigenic polysaccharide when cloned in Escherichia coli. The polysaccharide antigen was not detectable in E. faecalis strains, however. Here, we show by reverse transcriptase-PCR that the 16 genes in this region are transcribed in OG1RF. Gene disruption of orfde4, encoding a putative glycosyl transferase, and orfde6, a putative dTDP-rhamnose biosynthesis gene, generated two OG1RF mutants. The mutants showed delayed killing and a higher 50% lethal dose in a mouse peritonitis model. In addition, two mucoid E. faecalis isolates from patients with chronic urinary tract infections were found to produce the polysaccharide antigen.
此前，我们描述了粪肠球菌OG1RF的一个基因簇，该基因簇在克隆到大肠杆菌中时会产生一种抗原性多糖。然而，在粪肠球菌菌株中未检测到这种多糖抗原。在这里，我们通过逆转录聚合酶链反应表明，该区域的16个基因在OG1RF中被转录。对编码假定糖基转移酶的orfde4和假定的dTDP-鼠李糖生物合成基因orfde6进行基因破坏，产生了两个OG1RF突变体。在小鼠腹膜炎模型中，这些突变体显示出杀伤延迟和较高的50%致死剂量。此外，从慢性尿路感染患者中分离出的两种黏液样粪肠球菌菌株被发现能产生多糖抗原。
