Properties of cell wall-associated DD-carboxypeptidase of Enterococcus hirae (Streptococcus faecium) ATCC 9790 extracted with alkali.
DD-Carboxypeptidase (DD-CPase) activity of Enterococcus hirae (Streptococcus faecium) ATCC 9790 was extracted from intact bacteria and from the insoluble residue (crude cell wall fraction) of mechanically disrupted bacteria by a brief treatment at pH 10.0 (10 mM glycine-NaOH) at 0 degrees C or by extraction with any of several detergents. Extractions with high salt concentrations failed to remove DD-CPase activity from the crude wall fraction. In contrast to N-acetylmuramoylhydrolase (both muramidase 2 and muramidase 1) activities, DD-CPase activity failed to bind to insoluble cell walls or peptidoglycan matrices. Thus, whereas muramidase 1 and muramidase 2 activities can be considered to be cell wall proteins, the bulk of the data are consistent with the interpretation that the DD-CPase of this species is a membrane protein that is sometimes found in the cell wall fraction, presumably because of hydrophobic interactions with other proteins and cell wall polymers. The binding of [14C]penicillin to penicillin-binding protein 6 (43 kilodaltons) was proportional to DD-CPase activity. Kinetic parameters were also consistent with the presence of only one DD-CPase (penicillin-binding protein 6) in E. hirae.
Kariyama
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R
Department of Microbiology and Immunology, School of Medicine, Temple University, Philadelphia, Pennsylvania 19140.
Massidda
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O
Daneo-Moore
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L
Shockman
G D
GD
D002462:Cell Membrane / Q000201:enzymology; D002473:Cell Wall / Q000201:enzymology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008970:Molecular Weight; D002267:Muramoylpentapeptide Carboxypeptidase / Q000302:isolation & purification / Q000378:metabolism*; D010400:Penicillin G / Q000378:metabolism; D011485:Protein Binding; D011523:Protoplasts / Q000201:enzymology; D013291:Streptococcus / Q000201:enzymology*; D014461:Ultracentrifugation / Q000379:methods
D002267:Muramoylpentapeptide Carboxypeptidase; D010400:Penicillin G