Cheung A L, Wolz C, Yeaman M R, Bayer A S
Laboratory of Bacterial Pathogenesis and Immunology, Rockefeller University, New York 10021, USA.
J Bacteriol. 1995 Jun;177(11):3220-6. doi: 10.1128/jb.177.11.3220-3226.1995.
A single insertion of transposon Tn551 into a unique chromosomal locus of Staphylococcus aureus ISP479C has resulted in a pleiotropic effect on the expression of both extracellular and cell wall proteins. In particular, the expression of cell wall protein A and clumping activity with fibrinogen were rendered undetectable in the mutant 1E3 compared with the parent. The secretion of alpha-hemolysin in mutant 1E3 was modestly increased. Southern blot and phenotypic analyses indicated that this locus is distinct from agr, xpr, and sar, three previously described global regulatory loci. Transduction experiments demonstrated that the genotype associated with mutant 1E3 could be transferred back into the parental strain ISP479C. The transductant 1E3-2 displayed a phenotypic profile similar to that of the original mutant. Northern (RNA) blot studies showed that this locus may be involved in modulating target genes at the mRNA level. In the rabbit endocarditis model, there was a significant decrease in both the infectivity rate and intravegetation bacterial density with mutant 1E3 compared with the parent at an inoculum of 10(3) CFU. Since protein A and the fibrinogen-binding protein(s) are major surface proteins that may mediate bacterial adhesion to host tissues, this locus may be an important genetic element involved in the expression of virulence determinants in S. aureus.
转座子Tn551单次插入金黄色葡萄球菌ISP479C的一个独特染色体位点，对细胞外蛋白和细胞壁蛋白的表达产生了多效性影响。特别是，与亲本相比，在突变体1E3中无法检测到细胞壁蛋白A的表达以及与纤维蛋白原的凝集活性。突变体1E3中α-溶血素的分泌略有增加。Southern印迹和表型分析表明，该位点与agr、xpr和sar这三个先前描述的全局调控位点不同。转导实验表明，与突变体1E3相关的基因型可以转移回亲本菌株ISP479C。转导子1E3-2表现出与原始突变体相似的表型特征。Northern（RNA）印迹研究表明，该位点可能在mRNA水平参与调节靶基因。在兔心内膜炎模型中，接种10(3) CFU时，与亲本相比，突变体1E3的感染率和赘生物内细菌密度均显著降低。由于蛋白A和纤维蛋白原结合蛋白是可能介导细菌与宿主组织粘附的主要表面蛋白，该位点可能是参与金黄色葡萄球菌毒力决定因素表达的重要遗传元件。
