PBP5 complementation of a PBP3 deficiency in Enterococcus hirae.
The low susceptibility of enterococci to beta-lactams is due to the activity of the low-affinity penicillin-binding protein 5 (PBP5). One important feature of PBP5 is its ability to substitute for most, if not all, penicillin-binding proteins when they are inhibited. That substitution activity was analyzed in Enterococcus hirae SL2, a mutant whose pbp5 gene was interrupted by the nisRK genes and whose PBP3 synthesis was submitted to nisin induction. Noninduced SL2 cells were unable to divide except when plasmid-borne pbp5 genes were present, provided that the PBP5 active site was functional. Potential protein-protein interaction sites of the PBP5 N-terminal module were mutagenized by site-directed mutagenesis. The T167-L184 region (designated site D) appeared to be an essential intramolecular site needed for the stability of the protein. Mutations made in the two globular domains present in the N-terminal module indicated that they were needed for the suppletive activity. The P197-N209 segment (site E) in one of these domains seemed to be particularly important, as single and double mutations reduced or almost completely abolished, respectively, the action of PBP5.
Leimanis
S
S
Centre d'Ingénierie des Protéines, Université de Liège, Institut de Chimie, B6, B-4000 Liège, Belgium.
Hoyez
N
N
Hubert
S
S
Laschet
M
M
Sauvage
Eric
E
Brasseur
R
R
Coyette
J
J
D016983:Enterococcus / Q000235:genetics* / Q000254:growth & development; D005816:Genetic Complementation Test; D008958:Models, Molecular; D046915:Penicillin-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D017354:Point Mutation; D011485:Protein Binding
D046915:Penicillin-Binding Proteins