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. 2006 Jul;188(13):4851–4860. doi: 10.1128/JB.00345-06

FIG. 3.

FIG. 3.

Characterization of the FppA prepilin peptidase. (A) T-COFFEE multiple alignment of FppA and its homologues, OrfB from A. actinomycetemcomitans and CpaA from C. crescentus. Portions inconsistent between the combined alignments are in green and blue, and consistent ones are in yellow, orange, or red. The conserved aspartate residues (catalytic site) between the three aligned prepilin peptidases are marked with an asterisk. (B) Membrane topology model of the FppA protein. Each circle represents one of the 160 FppA residues. Black circles are located within each of the four predicted transmembrane domains of FppA. Gray residues indicate the position of the two conserved aspartate residues of the TFPP active site. (C) Production and maturation of Flp prepilin from PAO1/pMMBflp (lane 1), PAO1ΔfppA/pMMBflp (lane 2), and PAO1ΔpilD/pMMBflp (lane 8). The arrows on the left indicate the precursor (p) and mature (m) forms of the Flp pilin. Flp processing was also monitored in PAO1ΔfppA/pMMBflp containing pBBR1MCS-2 (lane 4), pBBRfppA (lane 3), or one of the fppA(D17A) (lane 5), fppA(D78A) (lane 6), or fppA(D17/78A) (lane 7) mutated genes. Proteins were separated by electrophoresis on a Tris-glycine gel.