Open AccessA Role in vivo for Penicillin‐Binding Protein‐4 of Staphylococcus aureus
Author(s) -
WYKE Anne W.,
WARD J.Barrie,
HAYES Michael V.,
CURTIS Nigel A.C.
Publication year - 1981
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1981.tb05620.x
Subject(s) - peptidoglycan , cefoxitin , penicillin binding proteins , staphylococcus aureus , penicillin , benzylpenicillin , microbiology and biotechnology , mutant , biochemistry , in vivo , antibiotics , biology , enzyme , chemistry , bacteria , gene , genetics
The degree of cross‐linking of the peotidoglycan of Staphylococcus aureus H and mutants lacking penicillin‐binding proteins 1 and 4 was studies. No major changes were ovserved in organisms lacking protein 1 whereas oloss of protein 4 was accompanied by a marked reduction in the degree of cross‐linked and the absence of a membrane‐bound ‘model’ transpeptidase activity. A smimlar effect was achieved when cultures of the staphylococci were treated with the β‐lactam antibiotic cefoxitin. At low concentrations (0.05μg ml‐1) cefoxition shows highest affinity for protein 4 to which it appears to bind irreversibly. Treatment of the mutant lacking protein 4 with this concentration of the antibiotic did not affect the degree of cross‐linkage. The possibility that the decrease in cross‐linkage was a consequence of DD‐carboxypeptidase activity on peptidoglycan precursors was investigated. Although both S. aureus H and the mutants possessed such activity it was insensitive to benzylpenicillin and cefoxition and the role of this enzyme(s) in peptidoglycan biosynthesis remains unknown. We conclude that in vivo protein 4 acts as a transpeptidase involved in the secondary cross‐linking of peptidoglycan and this activity is necessary to achieve the high degree of cross‐linkage observed in the peptidoglycan of staphylococci.