Factors Affecting the Collagen Binding Capacity of Staphylococcus aureus

Abstract

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.

Characterizing the effects of inorganic acid and alkaline shock on theStaphylococcus aureustranscriptome and messenger RNA turnover

“…Staphylococcus aureus strain UAMS‐1 is a well‐characterized osteomyelitis clinical isolate (Gillaspy et al , 1995; Cassat et al , 2005). Staphylococcus aureus strains CYL6194 and UAMS‐1274 are isogenic capsule and sigma β‐deficient strains, respectively (Gillaspy et al , 1998; Anderson et al , 2006).…”

Comparison of adhesion of wound isolates of Staphylococcus aureus to immobilized proteins

“…The presence of the gene for a particular adhesin does not necessarily result in the ability to bind to a particular protein. For example, not all strains carrying cna express it or Cna may be masked by the presence of a capsule (Gillaspy et al . 1998).…”

Encapsulated Staphylococcus aureus strains vary in adhesiveness assessed by atomic force microscopy

“…Indeed, several works demonstrate the masking of adhesins for mucoid strains. 16,33 We were interested in nonspecific adhesion phenomena, which occur in the absence of adhesins or ligands and are mediated by the surface characteristics of a bacterium. Although previous studies investigated the ability of S. aureus to adhere to certain types of materials, none quantitatively assessed adhesion.…”