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Characterization of HMW‐PBPs from the rod‐shaped actinomycete Corynebacterium glutamicum : peptidoglycan synthesis in cells lacking actin‐like cytoskeletal structures
Author(s) -
Valbueoelia,
Letek Michal,
Ordóñez Efrén,
Ayala Juan,
Daniel Richard A.,
Gil José A.,
Mateos Luis M.
Publication year - 2007
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2007.05943.x
Subject(s) - penicillin binding proteins , corynebacterium glutamicum , biology , peptidoglycan , gene , cell wall , biochemistry , sequence motif , bacterial protein
Summary Analysis of the complete genome sequence of Corynebacterium glutamicum indicated that, in addition to ftsI , there are eight proteins with sequence motifs that are strongly conserved in penicillin binding proteins (PBPs): four genes that code for high‐molecular‐weight (HMW)‐PBPs (PBP1a, PBP1b, PBP2a and PBP2b), two genes encoding low‐molecular‐weight PBPs (PBP4 and PBP4b) and two probable β‐lactamases (PBP5 and PBP6). Here, the function of the four HMW‐PBPs in C. glutamicum was investigated using a combination of genetic knockouts, enhanced green fluorescent protein 2 (EGFP2) fusions and penicillin staining of membrane preparations. The four HMW‐PBPs were expressed in a growing culture of C. glutamicum , but none of four pbp genes was individually essential for the growth of the bacterium, and only the simultaneous disruption of both pbp1b and pbp2b was lethal. The fused EGFP2–PBP proteins were functional in vivo , which allowed correct determination of their cellular localization. EGFP2 fusions to PBP1a, PBP1b and PBP2b localized at the poles and at the septum, whereas EGFP2–PBP2a was predominantly found at the septum. Cefsulodin treatment specifically delocalized PBP1a and PBP1b (class A HMW‐PBPs), whereas mecillinam caused the specific delocalization of PBP2b and PBP2a (class B HMW‐PBPs). The results provide new insight into the mechanisms involved in the synthesis of the cell wall in this bacterial species, which lacks a known actin‐like cytoskeletal structure.