title: Nna1-like proteins are active metallocarboxypeptidases of a new and diverse M14 subfamily.
abstract: Nna1 has some sequence similarity to metallocarboxypeptidases, but the biochemical characterization of Nna1 has not previously been reported. In this work we performed a detailed genomic scan and found >100 Nna1 homologues in bacteria, Protista, and Animalia, including several paralogs in most eukaryotic species. Phylogenetic analysis of the Nna1-like sequences demonstrates a major divergence between Nna1-like peptidases and the previously known metallocarboxypeptidases subfamilies: M14A, M14B, and M14C. Conformational modeling of representative Nna1-like proteins from a variety of species indicates an unusually open active site, a property that might facilitate its action on a wide variety of peptide and protein substrates. To test this, we expressed a recombinant form of one of the Nna1-like peptidases from Caenorhabditis elegans and demonstrated that this protein is a fully functional metallocarboxypeptidase that cleaves a range of C-terminal amino acids from synthetic peptides. The enzymatic activity is activated by ATP/ADP and salt-inactivated, and is preferentially inhibited by Z-Glu-Tyr dipeptide, which is without precedent in metallocarboxypeptidases and resembles tubulin carboxypeptidase functioning; this hypothesis is strongly reinforced by the results depicted in Kalinina et al. published as accompanying paper in this journal. Our findings demonstrate that the M14 family of metallocarboxypeptidases is more complex and diverse than expected, and that Nna1-like peptidases are functional variants of such enzymes, representing a novel subfamily (we propose the name M14D) that contributes substantially to such diversity.
authors.affiliation: Institut de Biotecnologia i de Biomedicina, Universitat Autonoma de Barcelona, 08193 Bellaterra (Barcelona), Spain.
authors.forename: Monica
authors.initials: M
authors.lastname: Rodriguez de la Vega
authors.forename: Rafael G
authors.initials: RG
authors.lastname: Sevilla
authors.forename: Antoni
authors.initials: A
authors.lastname: Hermoso
authors.forename: Julia
authors.initials: J
authors.lastname: Lorenzo
authors.forename: Sebastian
authors.initials: S
authors.lastname: Tanco
authors.forename: Amalia
authors.initials: A
authors.lastname: Diez
authors.forename: Lloyd D
authors.initials: LD
authors.lastname: Fricker
authors.forename: José M
authors.initials: JM
authors.lastname: Bautista
authors.forename: Francesc X
authors.initials: FX
authors.lastname: Avilés
mesh_terms: D000818:Animals; D001419:Bacteria / Q000201:enzymology / Q000235:genetics; D001483:Base Sequence; D001665:Binding Sites; D002268:Carboxypeptidases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D010447:Peptide Hydrolases / Q000145:classification* / Q000378:metabolism; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D046929:Serine-Type D-Ala-D-Ala Carboxypeptidase / Q000737:chemistry / Q000235:genetics*
chemical_list: D002268:Carboxypeptidases; D010447:Peptide Hydrolases; D046929:Serine-Type D-Ala-D-Ala Carboxypeptidase; C420042:Agtpbp1 protein, mouse; C023212:tyrosyltubulin carboxypeptidase; D019204:GTP-Binding Proteins