title: The members of M20D peptidase subfamily from Burkholderia cepacia, Deinococcus radiodurans and Staphylococcus aureus (HmrA) are carboxydipeptidases, primarily specific for Met-X dipeptides.
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.
authors.affiliation: Food Technology Division, Bhabha Atomic Research Centre, Mumbai, India. Electronic address: snjam2@gmail.com.
authors.forename: Sahayog N
authors.initials: SN
authors.lastname: Jamdar
authors.affiliation: High Pressure & Synchrotron Radiation Physics Division, Bhabha Atomic Research Centre, Mumbai, India.
authors.forename: Venkata N
authors.initials: VN
authors.lastname: Are
authors.affiliation: Food Technology Division, Bhabha Atomic Research Centre, Mumbai, India.
authors.forename: Mallikarjunan
authors.initials: M
authors.lastname: Navamani
authors.affiliation: Food Technology Division, Bhabha Atomic Research Centre, Mumbai, India.
authors.forename: Saurabh
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Food Technology Division, Bhabha Atomic Research Centre, Mumbai, India.
authors.forename: Vandan
authors.initials: V
authors.lastname: Nagar
authors.affiliation: High Pressure & Synchrotron Radiation Physics Division, Bhabha Atomic Research Centre, Mumbai, India.
authors.forename: Ravindra D
authors.initials: RD
authors.lastname: Makde
mesh_terms: D000595:Amino Acid Sequence; D049148:Aminoacylation; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D019121:Burkholderia Infections / Q000382:microbiology; D016956:Burkholderia cepacia / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism; D034301:Deinococcus / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism; D004151:Dipeptides / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010447:Peptide Hydrolases / Q000737:chemistry / Q000378:metabolism*; D016415:Sequence Alignment; D013203:Staphylococcal Infections / Q000382:microbiology; D013211:Staphylococcus aureus / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D004151:Dipeptides; C425144:HmrA protein, Staphylococcus aureus; D010447:Peptide Hydrolases
keywords: Aminoacylase/carboxypeptidase; Burkholderia cepacia; Deinococcus radiodurans; HmrA; Peptidase family M20D; Staphylococcus aureus