FIG 1.

A SNP in the tar locus of clinical S. aureus isolates is associated with higher levels of WTA and cytolytic activity. (a) The cytotoxicity of each clinical isolate is presented from the highest to the lowest, with the isolates containing the SNP in the tar locus indicated in red. (b) The SNP-containing clinical isolates produce significantly more WTA than an equivalent number of isolates that do not contain the SNP, as determined by the phosphorus content of the WTA extracts. The graph represents the amounts of phosphorus extracted from a 4-mL culture (at an OD₆₀₀ of 4). Each dot represents one isolate (n = 10 for each group), error bars represent the standard deviation, and statistical significance was determined by a t test. (c) Illustration of the position of the SNP within the tar locus; promoter features (P) were predicted using Softberry BPROM (http://www.softberry.com) (53). As indicated by the dashed line, there is evidence that the tarF promoter can read through and transcribe tarIJL, despite their having their own promoter (50).