title: Mouse cytosolic and mitochondrial deoxyribonucleotidases: cDNA cloning of the mitochondrial enzyme, gene structures, chromosomal mapping and comparison with the human orthologs.
abstract: Two of the five known mammalian 5'-nucleotidases show a preference for the dephosphorylation of deoxynucleoside-5'-phosphates. One is a cytoplasmic enzyme (dNT-1), the other occurs in mitochondria (dNT-2). The human mitochondrial enzyme, recently discovered and cloned by us, is encoded by a nuclear gene located on chromosome 17 p11.2 in the critical region deleted in the Smith-Magenis syndrome (SMS), a genetic disease of unknown etiology. Looking for a model system to study the possible involvement of dNT-2 in the disease, we have cloned the cDNA of the mouse ortholog. The deduced protein sequence is 84% identical to the human ortholog, has a very basic NH(2)-terminus, a very high calculated probability of being imported into mitochondria and contains the DXDXT/V motif conserved among nucleotidases. Expression in Escherichia coli of the predicted processed form of the protein produced an active deoxyribonucleotidase. We also identified in genomic sequences present in the data base the structures of the murine genes for the cytosolic and mitochondrial deoxyribonucleotidases (Nt5c and Nt5m). PAC clones for the two loci were isolated from a library and used for chromosomal localization by fluorescent in situ hybridization. Both genes map on chromosome 11: Nt5c at 11E and Nt5m at 11B, demonstrating the presence of the dNT-2 locus in the mouse shaker-2 critical region, the murine counterpart of the human SMS region. We performed pair-wise dot-plot and PIP (percent identity plot) analyses of mouse and human deoxyribonucleotidase genes, and found a strong conservation that extends also to some intronic sequences of possible regulatory significance.
authors.affiliation: Department of Biology, University of Padua, Via Ugo Bassi 58B, I 35131, Padua, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Rampazzo
authors.forename: Maria
authors.initials: M
authors.lastname: Kost-Alimova
authors.forename: Benedetta
authors.initials: B
authors.lastname: Ruzzenente
authors.forename: Jan P
authors.initials: JP
authors.lastname: Dumanski
authors.forename: Vera
authors.initials: V
authors.lastname: Bianchi
mesh_terms: D015720:5'-Nucleotidase / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D003600:Cytosol / Q000201:enzymology*; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D019143:Evolution, Molecular; D005796:Genes / Q000235:genetics; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007527:Isoenzymes / Q000235:genetics; D051379:Mice; D008928:Mitochondria / Q000201:enzymology*; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D026801:Synteny
chemical_list: D018076:DNA, Complementary; D007527:Isoenzymes; C063766:5'(3')-nucleotidase; D015720:5'-Nucleotidase