Alteration of virulence phenotype in the <i>psm-mec</i>-transformed <i>S. epidermidis</i>.

Abstract

<p>(A) Schematic representation of the <i>psm-mec</i> mutations in pC1, pC2, pC3, pM1, and pM2 is shown. (B) The amount of PSM-mec protein was measured by reversed-phase HPLC in the <i>S. epidermidis</i> strains transformed with plasmids listed in (A). Data are means ± standard deviations from three independent experiments. Asterisks indicate Student’s t-test p value less than 0.05 between the pF-transformed stain and the others. ND means not detected. (C) The amount of <i>psm-mec</i> RNA was measured by quantitative RT-PCR in the <i>S. epidermidis</i> strains transformed with plasmids listed in (A). Data shown are means ± standard deviations from three independent experiments. Asterisk indicates Student’s t-test p value less than 0.05 between the pF-transformed stain and the others. ND means not detected. (D) Extracellular proteins of overnight culture of <i>S. epidermidis</i> ATCC12228 strain, which was transformed with pND50 as an empty vector, pF carrying intact <i>psm-mec</i>, or plasmids carrying mutated <i>psm-mec</i> (pC1, pC2, pC3, pM1, or pM2) was electrophoresed in a 10% SDS polyacrylamide gel and stained by Coomassie brilliant blue. A representative result from three independent experiments is shown. (E) Expression of PSMs in the <i>psm-mec</i>-transformed strain (pF, magenta line) or empty vector-transformed strain (pND50, black line) was analyzed by reversed-phase HPLC. The PSM species were identified by LC/ESI-MS. (F, G, H, I) The amounts of PSMα + PSMδ, PSMγ, PSMβ1, and PSMβ2 in the <i>S. epidermidis</i> strain that was transformed with pND50 as an empty vector, pF carrying intact <i>psm-mec</i>, or plasmids carrying mutated <i>psm-mec</i> (pC1, pC2, pC3, pM1, or pM2) were measured by reversed-phase HPLC. The vertical axis represents the relative value to the amount of PSMs in the pND50-transformed strain. Data are shown as means ± standard deviations from three independent experiments. Asterisks indicate Student’s t-test with a p value less than 0.05 between the pND50-transformed stain and others. (J) Biofilm formation of the <i>S. epidermidis</i> strains transformed with pND50 as an empty vector, pF carrying intact <i>psm-mec</i>, or plasmids carrying mutated <i>psm-mec</i> (pC1, pC2, pC3, pM1, or pM2) was measured. Data shown are means ± standard deviations from three independent experiments. Asterisks indicate Student’s t-test with a p value less than 0.05 between the pF-transformed stain and the others.</p