• Title, Summary, Keyword: Phosphomannose-isomerase

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Mannose-Based Selection with Phosphomannose-Isomerase (PMI) Gene as a Positive Selectable Marker for Rice Genetic Transformation

  • Penna, Suprasanna;Ramaswamy, Manjunatha Benakanare;Anant., Bapat Vishvas.
    • Journal of Crop Science and Biotechnology
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    • v.11 no.4
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    • pp.233-236
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    • 2008
  • A positive selectable marker system was adapted for transformation of mature embryo-derived calli of Indica rice (Oryza sativa L.) utilizing the PMI gene encoding for phosphomannose-isomerase that converts mannose-6-phosphate to fructose-6-phosphate. The transformed cells grew on medium supplemented with 3% mannose as carbon source and calli were selected on media containing various concentrations of mannose. Molecular analyses showed that the transformed plants contained the PMI gene. The results indicate that the mannose selection system can be used for Agrobacterium-mediated transformation of mature embryo in rice to substitute the use of conventional selectable markers in genetic transformation.

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Cloning and characterization of phosphomannose isomerase from sphingomonas chungbukensis DJ77

  • Tran, Sinh Thi;Le, Dung Tien;Kim, Young-Chang;Shin, Malshik;Choi, Jung-Do
    • BMB Reports
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    • v.42 no.8
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    • pp.523-528
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    • 2009
  • Phosphomannose isomerase (PMI) catalyzes the interconversion of fructose-6-phosphate and mannose-6-phosphate in the extracellular polysaccharide (EPS) synthesis pathway. The gene encoding PMI in Sphingomonas chungbukensis DJ77 was cloned and expressed in E. coli. The pmi gene is 1,410 nucleotides long and the deduced amino acid sequence shares high homology with other bifunctional proteins that possess both PMI and GDP-mannose pyrophosphorylase (GMP) activities. The sequence analysis of PMI revealed two domains with three conserved motifs: a GMP domain at the N-terminus and a PMI domain at the C-terminus. Enzyme assays using the PMI protein confirmed its bifunctional activity. Both activities required divalent metal ions such as $Co^{2+}$, $Ca^{2+}$, $Mg^{2+}$, $Ni^{2+}$ or $Zn^{2+}$. Of these ions, $Co^{2+}$ was found to be the most effective activator of PMI. GDP-D-mannose was found to inhibit the PMI activity, suggesting feedback regulation of this pathway.

Genes involved in leaf senescence and regulation of their expression

  • Watanabe, Akira;Fujiki, Yuki;Yoshikawa, Yoko;Biswall, Basanti;Ito, Masaki
    • Proceedings of the Botanical Society of Korea Conference
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    • pp.63-67
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    • 1999
  • We have isolated more than a dozen cDNA clones corresponding to genes that were expressed in Arabidopsis leaves when they were kept in the dark. The nucleotide sequence analysis showed that some of the clones encoded proteins with significant homology to $\beta$-glucosidase (din2), branched-chain $\alpha$-keto acid dehydrogenase subunit E1$\beta$(din3), and another subunit E2 (din4), yeast RAD23 (din5), asparagine synthetase (din6), pre-mRNA splicing factor SRp35 (din7), phosphomannose isomerase (din9), seed imbibition protein (din10), and 2-oxoacid-dependent oxidase (din11). Accumulation of transcripts from din3,4,6 and 10 occurred rapidly after the plants were transferred to darkness. Transcripts from din2,9, and 11 could be detected only after 24 h of dark treatment. Inhibition of photo-synthesis by DCMU strongly induced the accumulation of transcripts from those genes, and application of sucrose to detached leaves suppressed the accumulation both in the dark and by DCMU. These observations indicate that expression of the genes is caused by sugar starvation resulted from the cessation of photosynthesis. We further showed that din2-encoded protein also accumulated in senescing leaves. Given these results, possible roles of din genes in leaves in the dark and senescing leaves are discussed.

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