Assembly of mutant pilins in Pseudomonas aeruginosa: formation of pili composed of heterologous subunits.
Recently, we reported the degree of N-terminal processing within the cytoplasmic membranes of three mutant pilins from Pseudomonas aeruginosa PAK with respect to leader peptide removal and the methylation of the N-terminal phenylalanine (B. L. Pasloske and W. Paranchych, Mol. Microbiol. 2:489-495, 1988). The results of those experiments showed that the deletion of 4 or 8 amino acids within the highly conserved N terminus greatly inhibited leader peptide removal. On the other hand, the mutation of the glutamate at position 5 to a lysine permitted leader peptide cleavage but inhibited transmethylase activity. In this report, we have examined the effects of these mutant pilins upon pilus assembly in a P. aeruginosa PAO host with or without the chromosomally encoded pilin gene present. Pilins with deletions of 4 or 8 amino acids in the N-terminal region were not incorporated into pili. Interestingly, pilin subunits containing the glutamate-to-lysine mutation were incorporated into compound pili together with PAO wild-type subunits. However, the mutant pilins were unable to polymerize as a homopolymer. When wild-type PAK and PAO pilin subunits were expressed in the same bacterial strain, the pilin subunits assembled into homopolymeric pili containing one or the other type of subunit.
Pasloske
B L
BL
Department of Biochemistry, University of Alberta, Edmonton, Canada.
Scraba
D G
DG
Paranchych
W
W
D001425:Bacterial Outer Membrane Proteins / Q000235:genetics* / Q000276:immunology; D015153:Blotting, Western; D004252:DNA Mutational Analysis; D036781:Fimbriae Proteins; D010861:Fimbriae, Bacterial / Q000648:ultrastructure*; D008854:Microscopy, Electron; D009024:Morphogenesis; D011550:Pseudomonas aeruginosa / Q000235:genetics* / Q000648:ultrastructure
D001425:Bacterial Outer Membrane Proteins; D036781:Fimbriae Proteins