Characterization of the sporulation-related gamma -D-glutamyl-(L)mesodiaminopimelic-acid-hydrolysing peptidase I of Bacillus sphaericus NCTC 9602 as a member of the metallo(zinc) carboxypeptidase A family. Modular design of the protein

• Published in: Biochemical journal 1993-01, Vol.292 (2), p.563-570
• Main Authors: Hourdou, M-L, Guinand, M, Vacheron, M-J, Michel, G, Denoroy, L, Duez, C, Englebert, S, Joris, B, Weber, G, Ghuysen, J-M
• Format: Article
• Language: English
• Subjects: Bacillus sphaericus; Enterococcus hirae; Streptomyces griseus
• ISSN: 0264-6021
• DOI: 10.1042/bj2920563

The sporulation-related gamma -D-glutamyl-(L)meso-diaminopimelic-acid-hydrolysing peptidase I of Bacillus sphaericus NCTC 9602 has been analysed by proton-induced X-ray emission. It contains 1 equivalent Zn super(2+) per mol of protein. As derived from gene cloning and sequencing, the B. sphaericus Zn peptidase I is a two-module protein. A 100-amino-acid-residue N-terminal domain consisting of two tandem segments of similar sequences, is fused to a 296-amino-acid-residue C-terminal catalytic domain. The catalytic domain belongs to the Zn carboxypeptidase A family, the closest match being observed with the Streptomyces griseus carboxypeptidase (Narahashi (1990) J. Biochem. 107, 879-886) and with the family prototype, bovine carboxypeptidase A. The catalytic domain of the B. sphaericus peptidase I possesses, distributed along the amino-acid sequence, peptide segments, a triad His super(162)-Glu super(165)-His super(307) and a dyad Tyr super(347)-Glu super(366) that are equivalent to secondary structures, the zinc-binding triad His super(69)-Glu super(72)-His super(196) and the catalytic dyad Tyr super(248)-Glu super(270) of bovine carboxypeptidase A respectively. The N-terminal repeats of the B. sphaericus peptidase I have similarity with the C-terminal repeats of the Enterococcus hirae muramidase 2, the Streptococcus (now Enterococcus) faecalis autolysin and the Bacillus Phi PZA and Phi 29 lysozymes, to which a role in the recognition of a particular moiety of the bacterial cell envelope has been tentatively assigned. Detergents enhance considerably the specific activity of the B. sphaericus peptidase I.