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Titolo:
Molecular genetics and structural biology of human MutT homolog, MTH1
Autore:
Nakabeppu, Y;
Indirizzi:
Kyushu Univ, Med Inst Bioregulat, Dept Biochem, Fukuoka 8128582, Japan Kyushu Univ Fukuoka Japan 8128582 , Dept Biochem, Fukuoka 8128582, Japan
Titolo Testata:
MUTATION RESEARCH-FUNDAMENTAL AND MOLECULAR MECHANISMS OF MUTAGENESIS
fascicolo: 1-2, volume: 477, anno: 2001,
pagine: 59 - 70
SICI:
1386-1964(20010602)477:1-2<59:MGASBO>2.0.ZU;2-0
Fonte:
ISI
Lingua:
ENG
Soggetto:
ESCHERICHIA-COLI MUTT; NUCLEOSIDE TRIPHOSPHATE PYROPHOSPHOHYDROLASE; OXIDATIVE DNA-DAMAGE; MUTAGENIC SUBSTRATE; ENCODING 8-OXO-DGTPASE; TRANSVERSION MUTATION; NUDIX HYDROLASES; MESSENGER-RNA; HUMAN-CELLS; ADP-RIBOSE;
Keywords:
nucleotide pool; oxidative stress; carcinogenesis; neuronal degeneration; oxidized purine nucleoside triphosphatase; mitochondria;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
44
Recensione:
Indirizzi per estratti:
Indirizzo: Nakabeppu, Y Kyushu Univ, Med Inst Bioregulat, Dept Biochem, Fukuoka 8128582, Japan Kyushu Univ Fukuoka Japan 8128582 m, Fukuoka 8128582, Japan
Citazione:
Y. Nakabeppu, "Molecular genetics and structural biology of human MutT homolog, MTH1", MUT RES-F M, 477(1-2), 2001, pp. 59-70

Abstract

The human MTH1 gene located on chromosome 7p22 consists of 5 major exons. MTH1 gene produces seven types of mRNAs and the B-type mRNAs with exon 2b-2c segments direct synthesis of three forms of MTH1 polypeptides (p22, p21, and p18) by alternative initiation of translation, while the others encode only p18. In human cells. p18, the major form is mostly localized in the cytoplasm with some in the mitochondria. A single nucleotide polymorphism (SNP) in exon 2, which is tightly liked to another SNP (GTG(83)/ATG(83)), creates an additional alternative in-frame AUG in B-type MTH1 mRNAs yielding the fourth MTH1 polypeptide, p26 that possesses an additional mitochondrial targeting signal. These SNPs are likely to be one of the risk factors for cancer or for neuronal degeneration. The 30 amino acid residues are identicalbetween MTH1 and MutT, and there is a highly conserved region consisting of 23 residues (MTH1: Gly36 to Gly58), with 14 identical residues. A chimeric protein in which the 23 residue sequence of MTH1 was replaced with that of MutT, retains the capability to hydrolyze 8-oxo-dGTP, indicating that the23 residue sequences of MTH1 and MutT are functionally and structurally equivalent, and constitute a functional phosphohydrolase module. Saturated mutagenesis of the module in MTH1 indicated that an amphipathic property of the alpha -helix I consisting of 14 residues of the module (Thr44 to Gly58) is essential to maintain the stable catalytic surface for 8-oxo-dGTPase. MTH1 but not MutT efficiently hydrolyzes two forms of oxidized dATP, 2-hydroxy-dATP and 8-oxo-dATP, as well as 8-oxo-dGTP and 8-oxo-GTP. Thus, MTH1 is designated as the oxidized purine nucleoside triphosphatase and has a much wider substrate specificity than MutT. There is a significant homology between MTH1 protein and the C-terminal half of human MYH protein, which may be involved in the recognition of 8-oxoguanine and 2-hydroxyadenine, (C) 2001 Elsevier Science B.V. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 18/01/20 alle ore 07:28:47