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PBP5 complementation of a PBP3 deficiency in Enterococcus hirae.
S Leimanis1, N Hoyez, S Hubert
1Centre d'Ingénierie des Protéines, Université de Liège, Institut de Chimie, B6, B-4000 Liège, Belgium.
Journal of Bacteriology
|August 23, 2006
Summary
Penicillin-binding protein 5 (PBP5) in enterococci is crucial for cell division and beta-lactam resistance. Its stability and function depend on specific protein regions, enabling it to substitute for other essential penicillin-binding proteins.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Enterococci exhibit low susceptibility to beta-lactam antibiotics due to the low-affinity penicillin-binding protein 5 (PBP5).
- PBP5 possesses a unique ability to compensate for the inhibition of other penicillin-binding proteins (PBPs).
Purpose of the Study:
- To investigate the substitution activity of PBP5 in Enterococcus hirae.
- To identify specific regions within PBP5 responsible for its stability and essential suppletive functions.
Main Methods:
- Site-directed mutagenesis was employed to analyze potential protein-protein interaction sites in the PBP5 N-terminal module.
- A mutant strain (Enterococcus hirae SL2) with an interrupted pbp5 gene and inducible PBP3 synthesis was utilized.
Main Results:
- Noninduced SL2 cells lacking functional PBP5 could not divide, highlighting PBP5's essential role in cell division.
- The T167-L184 region (site D) was identified as critical for PBP5 protein stability.
- Mutations within the N-terminal globular domains, particularly the P197-N209 segment (site E), significantly impaired PBP5's suppletive activity.
Conclusions:
- PBP5 is essential for enterococcal cell division and its stability is regulated by specific intramolecular sites.
- The N-terminal globular domains of PBP5 are vital for its compensatory function, with site E being particularly important.