NAD+-malic enzyme affects nitrogenase activity of Mesorhizobium loti bacteroids in Lotus japonicus nodules

Nanthipak Thapanapongworakul, Mika Nomura, Yoshikazu Shimoda, Shusei Sato, Satoshi Tabata, Shigeyuki Tajima

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    4 Citations (Scopus)


    A gram-negative bacterium, Mesorhizobium loti, contains a NADP+-malic enzyme (mlr5329) and a malate oxidoreductase (mlr0809) in the genome. We have screened transposon-induced mutants from the signature-tagged mutant library to survey their roles in nodule nitrogenase activity. The nodules induced by malate oxidoreductase mutants failed to fix N2, although NADP+-malic enzyme (NADP+-ME) mutants induced nodules exhibiting no change in nodule nitrogenase activity. When malate-degrading enzyme activities were compared between malate oxidoreductase mutants and wild-type M. loti, NAD+-malic enzyme (NAD+-ME) activity was decreased significantly in malate oxidoreductase mutants, suggesting it is an NAD+-ME mutant. We found that NADP+-ME was not required for N2 fixation. The fact that significant accumulations of sucrose, starch granules and malate were observed in the nodules induced by malate oxidoreductase mutant suggests that low nitrogenase activity of the nodules resulted in photosynthate accumulation. These data suggest that this malate oxidoreductase has a similar function to NAD+-ME in both Bradyrhizobium japonicum and Sinorhizobium meliloti.

    Original languageEnglish
    Pages (from-to)31-316
    Number of pages286
    JournalPlant Biotechnology
    Issue number4
    Publication statusPublished - 2010


    • Lotus japonicus
    • Mesorhizobium loti
    • STM mutant

    ASJC Scopus subject areas

    • Biotechnology
    • Agronomy and Crop Science
    • Plant Science

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