TAILIEUCHUNG - Báo cáo Y học: Cloning of the manganese lipoxygenase gene reveals homology with the lipoxygenase gene family

Manganese lipoxygenase was isolated to homogeneity from the take-all fungus, Gaeumannomyces graminis. The C-terminal amino acids and several internal peptides were sequenced, and the information was used to obtain a cDNA probe by RT/PCR. Screening of a genomic library of G. graminis yielded a full-length clone of the Mn-Lipoxygenase gene. cDNA analysis showed that the gene spanned kb and contained one intron (133 bp). Northern blot analyses indicated two transcripts ( and kb). The deduced amino-acid sequence of the Mn-Lipoxygenase precursor (618 amino acids, kDa) could be aligned with mammalian and plant lipoxygenases with 23–28% identity over. | Eur. J. Biochem. 269 2690-2697 2002 FEBS 2002 doi Cloning of the manganese lipoxygenase gene reveals homology with the lipoxygenase gene family Lena Hornsten1 Chao Su1 Anne E. Osbourn2 Ulf Hellman3 and Ernst H. Oliw1 1 Department of Pharmaceutical Biosciences Uppsala Biomedical Centre Uppsala Sweden 2The Sainsbury Laboratory John Innes Centre Norwich UK 3Ludwig Institute for Cancer Research Uppsala Biomedical Centre Uppsala Sweden Manganese lipoxygenase was isolated to homogeneity from the take-all fungus Gaeumannomyces graminis. The C-ter-minal amino acids and several internal peptides were sequenced and the information was used to obtain a cDNA probe by RT PCR. Screening of a genomic library of G. graminis yielded a full-length clone of the Mn-Lipoxyg-enase gene. cDNA analysis showed that the gene spanned kb and contained one intron 133 bp . Northern blot analyses indicated two transcripts and kb . The deduced amino-acid sequence of the Mn-Lipoxygenase precursor 618 amino acids kDa could be aligned with mammalian and plant lipoxygenases with 23-28 identity over 350-400 amino-acid residues of the catalytic domains. Lipoxygenases have one water molecule and five amino acids as Fe ligands. These are two histidine residues in the highly conserved 30 amino-acid sequence WLLAK-X15-H-X4-H-X3-E of a helix 9 one histidine and usually an asparaine residue in the sequence H-X3-N-X-G of a helix 18 and the carboxyl oxygen of the C-terminal isoleucine or valine residue. The homologous sequence of a helix 9 of Mn-Lipoxygenase WLLAK-X14-H 294 -X3-H 297 -X3-E contained two single-amino-acid gaps but otherwise His294 and His297 aligned with the two His residues which coordinate iron. Mn-Lipoxygenase H 478 -X3-N 482 -X-G could be aligned with the two metal ligands of a helix 18 and the C-terminal residue was Val618. We conclude that Mn-Lipoxygenase belongs to the lipoxygenase gene family and that its unique biochemical properties .

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