Inhibition of Competence Development, Horizontal Gene Transfer and Virulence in Streptococcus pneumoniae by a Modified Competence Stimulating Peptide
Figure 8
CSP2-E1A inhibits competence development and transformation in ComD2 strain TIGR4.
(A–B) CSP2-E1A was drastically reduced in its ability to induce the promoter activity of comX (A) and DNA transformation in TIGR4 (B). Experiments were performed in triplicates and repeated three times. The means ± SD of one typical experiment are shown. *p<0.01 when compared against TIGR4pcomX::lacZ cells (A) or TIGR4 cells (B) treated with CSP2 only. (C) CSP-E2A out-competes CSP2 and inhibits activation of the comX promoter activity. TIGR4pcomX::lacZ cells (OD 600nm 0.1) were incubated with 100 ng/ml CSP2 alone or simultaneously with increasing amounts of CSP2-E1A. The activity of comX promoter was measured by b-galactosidase assays. (D) CSP-E2A inhibits CSP2-mediated DNA transformation of TIGR4. In vitro transformation was performed by treating TIGR4 cells with 100 ng/ml CSP2 alone or simultaneously with increasing amount of CSP2-E1A. Purified PCR product of a mutated rpsL gene was used for genetic transformation. Transformants were selected on THB agar supplemented with 100 µg/ml streptomycin. Experiments in were performed in triplicates and repeated three times. The means ± SD of one typical experiment are shown. *p<0.01 when compared against TIGR4pcomX::lacZ cells (A) or TIGR4 cells (B) treated with CSP2 only.