title: Binding site-shaped repeated sequences of bacterial wall peptidoglycan hydrolases.
abstract: The non-catalytic C-terminal regions of the N-acetylmuramidase (lysozyme) of Clostridium acetobutylicum and N-acetylmuramoyl(D-lactyl)-L-alanine amidases CwlA of Bacillus subtilis, ORFL3 and CwlL of Bacillus licheniformis were previously reported to have similarities with the amino acid sequence of the non-catalytic N-terminal module of the Streptomyces albus G Zn DD-peptidase. This peptidase is a bipartite protein of known three-dimensional structure. Its non-catalytic N-terminal module possesses, exposed at the surface, an elongated crevice which is defined by a loop-helix-loop-helix motif that consists of two repeats, each 16 amino acid residues long, connected by a heptapeptide and whose design is compatible with its possible functioning as a substrate recognition and binding site. Amino acid alignments suggest that cavities nearly identical in shape to that present in the non-catalytic module of the S. albus peptidase, are borne by the C-terminal regions of the CwlA amidase (in one copy), the lysozyme and the ORFL3 and CwlL amidases (in two copies). Since a common feature of the five enzymes is their substrate, the bacterial cell wall peptidoglycan, we interpret the striking similarity of their non-catalytic N- or C-terminal modules to suggest that these modules are involved in the binding of these exocellular enzymes to their insoluble wall substrate.
authors.affiliation: Centre d'Ingénierie des Protéines, Université de Liège, Sart Tilman (Liège 1), Belgium.
authors.forename: J M
authors.initials: JM
authors.lastname: Ghuysen
authors.forename: J
authors.initials: J
authors.lastname: Lamotte-Brasseur
authors.forename: B
authors.initials: B
authors.lastname: Joris
authors.forename: G D
authors.initials: GD
authors.lastname: Shockman
mesh_terms: D000595:Amino Acid Sequence; D001407:Bacillus / Q000201:enzymology; D001412:Bacillus subtilis / Q000201:enzymology; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D003013:Clostridium / Q000201:enzymology; D008969:Molecular Sequence Data; D009113:Muramidase / Q000737:chemistry / Q000378:metabolism; D002267:Muramoylpentapeptide Carboxypeptidase / Q000737:chemistry* / Q000378:metabolism; D009238:N-Acetylmuramoyl-L-alanine Amidase / Q000737:chemistry* / Q000378:metabolism; D017510:Protein Folding; D017433:Protein Structure, Secondary; D016415:Sequence Alignment; D013302:Streptomyces / Q000201:enzymology*
chemical_list: D001426:Bacterial Proteins; D009113:Muramidase; D002267:Muramoylpentapeptide Carboxypeptidase; C084313:CwlL protein, Bacillus licheniformis; D009238:N-Acetylmuramoyl-L-alanine Amidase