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Factors Affecting the Collagen Binding Capacity ofStaphylococcus aureus

机译：影响金黄色葡萄球菌胶原结合能力的因素

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To determine whether the ability of Staphylococcus aureus to bind collagen involves an adhesin other than the collagen adhesin encoded by cna, we examined the collagen binding capacity (CBC) of 32 strains of S. aureus. With only two exceptions, a high CBC corresponded with the presence ofcna. Both exceptions involved cna-positive strains with a low CBC. The first was a single strain (ACH5) that encoded but did not express cna. The second were the mucoid strains Smith diffuse and M, both of which encoded and expressedcna but bound only minimal amounts of collagen. Analysis of capsule mutants suggests that the reduced CBC observed in the mucoid strains was due to masking of the collagen adhesin on the cell surface and that this masking effect is restricted to heavily encapsulated strains. Differences in the CBC of the remainingcna-positive strains were correlated to variations in the level of cna transcription and were independent of the number of B domain repeats in the cna gene. In allcna-positive strains other than ACH5, cnatranscription was temporally regulated, with cna mRNA levels being highest in cells taken from exponentially growing cultures and falling to almost undetectable levels as cultures entered the post-exponential growth phase. The CBC was also highest with cells taken from exponentially growing cultures. Mutation of agrresulted in a slight increase in cna transcription and a corresponding increase in CBC during the exponential growth phase but did not affect the temporal pattern of cna transcription. Mutation of sar resulted in a more dramatic increase in CBC and a delay in the post-exponential-phase repression of cnatranscription. Mutation of both sar and agr had an additive effect on both CBC and cna transcription. We conclude that (i) cna encodes the primary collagen-binding adhesin in S. aureus, (ii) sar is the primary regulatory element controlling expression of cna, and (iii) the regulatory effects of sar and agr oncna transcription are independent of the interaction between sar and agr.
机译：为了确定金黄色葡萄球菌结合胶原的能力是否涉及除 cna 编码的胶原黏附素以外的其他黏附素，我们检查了32株金黄色葡萄球菌的胶原结合能力（CBC）。 S。金黄色。除了两个例外，高CBC对应于 cna 的存在。两种例外都涉及CBC低的 cna 阳性菌株。第一个是编码但不表达 cna 的单一菌株（ACH5）。第二个是粘液菌史密斯弥散和M，它们都编码和表达 cna ，但只结合了少量的胶原蛋白。胶囊突变体的分析表明，在粘液样菌株中观察到的CBC降低是由于胶原粘附蛋白在细胞表面的掩蔽所致，并且这种掩盖作用仅限于重囊化的菌株。其余 cna 阳性菌株的CBC差异与 cna 转录水平的变化相关，并且与中B结构域重复的数量无关cna 基因。在除ACH5以外的所有 cna 阳性菌株中， cna 转录均受到时间调控， cna mRNA的水平在指数生长的培养细胞中最高。随着培养物进入指数后生长阶段，其水平几乎降至不可检测的水平。从成倍增长的培养物中提取的细胞，CBC也最高。在指数生长期， agr 的突变导致 cna 的转录略有增加，而CBC也相应增加，但不影响 cna的时间模式转录。 sar 的突变导致CBC的增加更为显着，并且 cna 转录的指数后阶段​​阻滞有所延迟。 sar 和 agr 的突变均对CBC和 cna 转录具有累加作用。我们得出的结论是（i） cna 编码 S中主要的胶原结合粘附素。金黄色，（ii） sar 是控制 cna 表达的主要调控元件，（iii） sar 的调控作用和 agr 在 cna 上的转录与 sar 和 agr 之间的相互作用无关。

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