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Truncated type IV pilin PilA108 activates the intramembrane protease AlgW to cleave MucA and PilA108 itself in vitro
- Li, Ronghui, Withers, Ryan T., Dai, Jingcheng, Ruan, Jing, Li, Wei, Dai, Yujun, An, Weixing, Yu, Dianzhen, Wei, Hehong, Xia, Ming, Tian, Chunyuan, Yu, Hongwei D., Qiu, Dongru
- Archives of microbiology 2016 v.198 no.9 pp. 885-892
- Pseudomonas aeruginosa, genes, models, point mutation, polypeptides, protein synthesis, proteinases
- For alginate production in Pseudomonas aeruginosa, the intramembrane protease AlgW must be activated to cleave the periplasmic domain of anti-sigma factor MucA for release of the sequestered ECF sigma factor AlgU. Previously, we reported that three tandem point mutations in the pilA gene, resulting in a truncated type IV pilin termed PilA¹⁰⁸ with a C-terminal motif of phenylalanine–threonine–phenylalanine (FTF), induced mucoidy in strain PAO579. In this study, we purified PilA¹⁰⁸ protein and synthesized a peptide ‘SGAGDITFTF’ corresponding to C-terminus of PilA¹⁰⁸ and found they both caused the degradation of MucA by AlgW. Interestingly, AlgW could also cleave PilA¹⁰⁸ between alanine⁶² and glycine⁶³ residues. Overexpression of the recombinant FTF motif-bearing MucE protein, originally a small periplasmic polypeptide with the C-terminal motif WVF, could induce mucoid conversion in the PAO1 strain. In all, our results provided a model of activation of AlgW by another protein ending with proper motifs. Our data suggest that in addition to MucA cleavage, AlgW may cleave other substrates.