McNab Roderick, Jenkinson Howard F
Molecular Oral Biology Laboratory, Department of Oral Biology and Oral Pathology, University of Otago, PO Box 647, Dunedin, New Zealand.
Microbiology (Reading). 1998 Jan;144 ( Pt 1):127-136. doi: 10.1099/00221287-144-1-127.
Cell-surface polypeptide CshA (259 kDa) mediates multiple adherence interactions of Streptococcus gordonii. By generating a chromosomal cshA promoter (p-cshA)-cat gene fusion and measuring both CAT enzyme activity and cat mRNA levels, it was shown that cshA is expressed maximally in cells in the late exponential phase of growth in batch culture. The expression of CAT enzyme activity from the p-cshA-cat promoter fusion was 28% decreased in early stationary phase cell extracts of mutant strain OB528 in which the hppA (oligopeptide-binding lipoprotein) gene was insertionally inactivated. This effect was correlated with proportionally reduced cell-surface expression of CshA protein and with impaired adherence of hppA mutant cells to cells of an oral Actinomyces naeslundii strain. cshA promoter activity was enhanced in streptococcal cells that were incubated in conditioned culture medium as opposed to fresh medium, but this did not occur in an hppA genetic background. It is suggested that HppA is necessary for the response of cells to an extracellular factor that modulates cshA transcription, and hence affects cell-surface CshA expression and streptococcal cell adherence properties.
细胞表面多肽CshA（259 kDa）介导戈登氏链球菌的多种黏附相互作用。通过构建染色体cshA启动子（p-cshA）-cat基因融合体并测量CAT酶活性和cat mRNA水平，结果表明，在分批培养的生长指数后期细胞中，cshA表达量最高。在hppA（寡肽结合脂蛋白）基因被插入失活的突变菌株OB528的早期稳定期细胞提取物中，来自p-cshA-cat启动子融合体的CAT酶活性表达降低了28%。这种效应与CshA蛋白在细胞表面的表达比例降低以及hppA突变细胞对口腔内氏放线菌菌株细胞的黏附受损相关。与新鲜培养基相比，在条件培养基中孵育的链球菌细胞中，cshA启动子活性增强，但在hppA基因背景下未出现这种情况。提示HppA对于细胞对调节cshA转录的细胞外因子的反应是必需的，因此影响细胞表面CshA表达和链球菌细胞黏附特性。
