ComA can process and secrete BlpC independently of BlpA.

<p>(A-C) <i>BIR</i><sub><i>P1</i></sub><i>-lacZ</i> transcriptional response in wildtype (blue circles), <i>blpA</i><sub><i>FS</i></sub> (purple octagon) and <i>blpA</i><sub><i>FS</i></sub>/<i>comAB</i> (red squares) mutant reporters during growth in broth. Closed symbols denote CSP addition, open symbols denote no peptide added. Cellular growth is shown as grey lines. (A) Response to CSP added at time 0 in THY. (B-C) Natural <i>BIR</i><sub><i>P1</i></sub><i>-lacZ</i> induction in competence permissive (B) and competence non-permissive C+Y media (C). (D) Western blot of cell lysate of BlpC<sub>FLAG</sub> expressing strains in <i>ΔhtrA</i> background: PSD127 (Wt), PSD131 (<i>ΔblpA</i>), PSD146 (<i>ΔcomAB</i>) and PSD147 (<i>ΔblpA/comAB</i>) after treatment with CSP or BlpC<sub>R6</sub> or both BlpC<sub>R6</sub>/CSP. Preprocessed BlpC<sub>FLAG</sub> is denoted as pre-BlpC, the processed form is BlpC. Anti-pneumolysin (Ply) antibody was used as a loading control. Densitometry analysis was performed to determine % processed BlpC<sub>FLAG</sub> of the total BlpC<sub>FLAG</sub> detected in each strain.</p>