PMID:26456402

Citation	Jamdar, SN, Are, VN, Navamani, M, Kumar, S, Nagar, V and Makde, RD (2015) The members of M20D peptidase subfamily from Burkholderia cepacia, Deinococcus radiodurans and Staphylococcus aureus (HmrA) are carboxydipeptidases, primarily specific for Met-X dipeptides. Arch. Biochem. Biophys. 587:18-30
Abstract	Three members of peptidase family M20D from Burkholderia cepacia (BcepM20D; Uniprot accession no. A0A0F7GQ23), Deinococcus radiodurans R1 (DradM20D; Uniprot accession no. Q9RTP6) and Staphylococcus aureus (HmrA; Uniprot accession no. Q99Q45) were characterized in terms of their preference for various substrates. The results thus reveal that all the enzymes including HmrA lack endopeptidase as well as aminopeptidase activities and possess strong carboxypeptidase activity. Further, the amidohydrolase activity exerted on other substrates like N-Acetyl-Amino acids, N-Carbobenzoxyl-Amino acids and Indole acetic acid (IAA)-Amino acids is due to the ability of these enzymes to accommodate different types of chemical groups other than the amino acid at the S1 pocket. Further, data on peptide hydrolysis strongly suggests that all the three enzymes are primarily carboxydipeptidases exhibiting highest catalytic efficiency (kcat/Km 5-36 × 10(5) M(-1) s(-1)) for Met-X substrates, where -X could be Ala/Gly/Ser/Tyr/Phe/Leu depending on the source organism. The supportive evidence for the substrate specificities was also provided with the molecular docking studies carried out using structure of SACOL0085 and homology modelled structure of BcepM20D. The preference for different substrates, their binding at active site of the enzyme and possible role of these enzymes in recycling of methionine are discussed in this study.
Links	PubMed Online version:10.1016/j.abb.2015.10.003
Keywords	Amino Acid Sequence; Aminoacylation; Bacterial Proteins/chemistry; Bacterial Proteins/metabolism; Burkholderia Infections/microbiology; Burkholderia cepacia/chemistry; Burkholderia cepacia/enzymology; Burkholderia cepacia/metabolism; Deinococcus/chemistry; Deinococcus/enzymology; Deinococcus/metabolism; Dipeptides/chemistry; Dipeptides/metabolism; Humans; Models, Molecular; Molecular Sequence Data; Peptide Hydrolases/chemistry; Peptide Hydrolases/metabolism; Sequence Alignment; Staphylococcal Infections/microbiology; Staphylococcus aureus/chemistry; Staphylococcus aureus/enzymology; Staphylococcus aureus/metabolism; Substrate Specificity
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