Family M99


Summary Holotypes Genomes Structure Literature

Summary for family M99

Family type peptidaseM99.001 - Csd4 peptidase (Helicobacter pylori) (Helicobacter pylori), MEROPS Accession MER0032094 (peptidase unit: 22-267)
Content of familyFamily M99 contains bacterial cell wall-degrading carboxypeptidases
History Identifier created: MEROPS 10.0 (14 Mar 2016)
Helicobacter pylori is a causative agent for peptic ulcers and gastric cancer. In order to survive in the stomach, the bacterium must colonize the gastric muucosa; colonization depends on motility, and this in turn depends upon the shape of the bacterium. A helically-shaped bacterium is more virulent (Sycuro et al., 2012). The bacterial shape is affected by reducing the number of cross-links or by trimming of the peptidoglycan muropeptides. The Csd4 protein (M99.001) is a zinc-dependent D,L-carboxypeptidase that cleaves a specific bond in a non-cross-linked muramyltripeptide, which in turn affects the cell shape (Kim et al., 2014).
Catalytic typeMetallo
Active site residuesQ46 E49 R86 H128 E222 
Activities and specificitiesThe Csd4 peptidase cleaves the bond between the gamma-D-Glu+mDAP bond of the non-cross-linked murayltripeptide muramyl-Ala-gamma-D-Glu-mDAP. The carboxypeptidase recognizes its substrate by interacting with the mDAP moiety and undergoes a significant structural change when mDAP is bound (Kim et al., 2014).
Molecular structureThe tertiary structure has been determined and and Csd4 protein consists of three domains, an N-terminal carboxypeptidase domain, a central beta-barrel domain, and a C-terminal immunoglobulin-like domain (Kim et al., 2014). The carboxypeptidase domain is structurally similar to that of carboxypeptidases in family M14, hence family M99 is included in clan MC.
Distribution of family Bacteria details  
Archaea -  
Protozoa -  
Fungi -  
Plants -  
Animals -  
Viruses -  
Biological functionsThe shape of the bacterium alters following release of the C-terminal amino acid from a non-cross-linked muramyltripeptide by the Csd4 carboxypeptidase. Csd5, another protein important for determining the shape of the bacterium, interacts with the Csd4 peptidase and with the dipeptide released by Csd4 cleavage (Sycuro et al., 2012).
Statistics for family M99Sequences:1
Identifiers with PDB entries:1
Downloadable files Sequence library (FastA format)
Peptidases and Homologues MEROPS ID Structure
Csd4 peptidase (Helicobacter pylori)M99.001Yes