Regulation of bacterial cell walls: correlation between autolytic activity and cell wall turnover in Staphylococcus aureus
Regulation of bacterial cell walls: correlation between autolytic activity and cell wall turnover in Staphylococcus aureus
复制标题
细菌细胞壁的调节：金黄色葡萄球菌自溶活性与细胞壁更新之间的相关性
作者：
W. Wong;A. Chatterjee;F. Young
研究了金黄色葡萄球菌亲本株和突变株的细胞壁周转情况。在指数生长过程中，野生型菌株的肽聚糖和磷壁酸发生了转换；然而，当生长速度减慢时，周转率并没有降低，因为培养进入了固定阶段。从指数和指数后生长阶段收获的细胞中分离出天然细胞壁和粗溶自溶酶。两个生长阶段的原生细胞壁在缓冲液中以相同的速率自溶；同样，来自两种制剂的粗溶酶以相同的速率降解放射性细胞壁。因此，指数和指数后细胞的自溶素活性相似。1.0 M NaCl可促进突变体tar-1的全细胞自溶。在生长条件下，当NaCl浓度为1.0 M时，细胞壁周转率大大提高。氯霉素的存在，抑制全细胞自溶，也抑制周转。对从废培养基中回收的细胞壁材料进行分析，发现产物与内源性自溶素的已知作用方式一致。由此可见，金黄色葡萄球菌的细胞壁周转与培养生长的阶段无关，而与自溶素的活性有关。
Cell wall turnover was examined in parent and mutant strains of Staphylococcus aureus. Peptidoglycan and teichoic acid were observed to undergo turnover in the wild-type strain during exponential growth; however, the rate of turnover did not decrease when the growth rate slowed, as the culture entered stationary phase. Isolated native cell walls and crude soluble autolytic enzyme were prepared from cells harvested during exponential and postexponential phases of growth. Native cell walls from both phases of growth autolyzed in buffer at identical rates; similarily, crude soluble enzyme from both preparations degraded radioactive cell walls at the same rate. Therefore, the activity of the autolysin in both exponential and postexponential cells was similar. The autolysis of whole cells of a mutant tar-1 was enhanced by 1.0 M NaCl. When 1.0 M NaCl was present under growing conditions, the rate of cell wall turnover was greatly increased. The presence of chloramphenicol, which inhibits whole-cell autolysis, also inhibited turnover. Analysis of the cell wall material recovered from spent medium revealed products consistent with the known mode of action of the endogenous autolysin. It is concluded that cell wall turnover in S. aureus is independent of the stage of culture growth but is dependent instead on the activity of the autolysin.