Lactococcus lactis gene yjgB encodes a gamma-D-glutaminyl-L-lysyl-endopeptidase which hydrolyzes peptidoglycan.
YjgB is one of five peptidoglycan hydrolases previously identified in Lactococcus lactis. Analysis of its amino acid sequence revealed that YjgB contains an NlpC/P60 domain, whereas no specific cell wall binding domain or motif could be identified. The NlpC/P60 family is characterized by three conserved residues, a cysteine, a histidine, and a polar residue. In agreement with the presence of a Cys residue in the catalytic site of YjgB, its enzymatic activity was enhanced in the presence of dithiothreitol. Peptidoglycan-hydrolyzing activity of YjgB was detected in growing cells of an L. lactis strain overexpressing YjgB, as revealed by the presence of disaccharide (DS)-dipeptide in the muropeptide composition of the overexpressing strain. YjgB hydrolyzes the peptide chains of L. lactis muropeptides between gamma-D-Gln and L-Lys residues. Its hydrolytic activity was detected on DSs with tetra- and pentapeptide chains, whereas hydrolytic activity was very low on DS-tripeptides. Thus, we demonstrated that YjgB is an endopeptidase which cleaves gamma-D-Gln-L-Lys bonds in peptide chains of L. lactis peptidoglycan.
Redko
Yulia
Y
INRA, Unité de Biochimie Bactérienne, UR477, 78352 Jouy-en-Josas Cedex, France.
Courtin
Pascal
P
Mézange
Christine
C
Huard
Carine
C
Chapot-Chartier
Marie-Pierre
MP
D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010450:Endopeptidases / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial / Q000235:genetics*; D013294:Lactococcus lactis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D010457:Peptidoglycan / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; D010457:Peptidoglycan; D010450:Endopeptidases; C038279:gamma-D-glutamyl-L-diaminoacid endopeptidase; C525702:yjgB protein, Lactococcus lactis