Substrate specificity of Escherichia coli LD-carboxypeptidase on biosynthetically modified muropeptides.
Escherichia coli murein can be biosynthetically modified. Amino acids at positions 3 and 4 (m-diaminopimelic acid and D-alanine, respectively) on the peptide moieties can be changed under appropriate growth conditions. The activity of E. coli LD-carboxypeptidase on biosynthetically modified substrates has been studied in vitro. The enzyme hydrolysed all tested disaccharide-tetrapeptide monomeric muropeptides modified at position 4. Monomers with m-lanthionine, but not with L-ornithine, instead of m-diaminopimelic acid at position 3 were accepted. However, neither cross-linked muropeptides nor macromolecular murein were substrates for the reaction. Our observations argue against a direct effect of LD-carboxypeptidase on macromolecular murein metabolism.
Leguina
J I
JI
Centro de Biologia Molecular Severo Ochoa CSIC-UAM, Facultad de Ciencias UAM, Madrid, Spain.
Quintela
J C
JC
de Pedro
M A
MA
D000409:Alanine; D000595:Amino Acid Sequence; D002268:Carboxypeptidases / Q000378:metabolism*; D003960:Diaminopimelic Acid; D004926:Escherichia coli / Q000201:enzymology*; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*; D010457:Peptidoglycan / Q000737:chemistry / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
D010455:Peptides; D010457:Peptidoglycan; D003960:Diaminopimelic Acid; D002268:Carboxypeptidases; C021505:LD-carboxypeptidase; D000409:Alanine