Nitric oxide detoxification in the rhizobia-legume symbiosis

Cristina Sánchez, Juan J. Cabrera, Andrew J. Gates, Eulogio J. Bedmar, David J. Richardson, María J. Delgado

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    38 Citations (Scopus)


    NO (nitric oxide) is a signal molecule involved in diverse physiological processes in cells which can become very toxic under certain conditions determined by its rate of production and diffusion. Several studies have clearly shown the production of NO in early stages of rhizobia-legume symbiosis and in mature nodules. In functioning nodules, it has been demonstrated that NO, which has been reported as a potent inhibitor of nitrogenase activity, can bind Lb (leghaemoglobin) to form LbNOs (nitrosyl-leghaemoglobin complexes). These observations have led to the question of how nodules overcome the toxicity of NO. On the bacterial side, one candidate for NO detoxification in nodules is the respiratory Nor (NO reductase) that catalyses the reduction of NO to nitrous oxide. In addition, rhizobial fHbs (flavohaemoglobins) and single-domain Hbs which dioxygenate NO to form nitrate are candidates to detoxify NO under free-living and symbiotic conditions. On the plant side, sHbs (symbiotic Hbs) (Lb) and nsHbs (non-symbiotic Hbs) have been proposed to play important roles as modulators of NO levels in the rhizobia-legume symbiosis. In the present review, current knowledge of NO detoxification by legume-associated endosymbiotic bacteria is summarized.

    Original languageEnglish
    Pages (from-to)184-188
    Number of pages5
    JournalBiochemical Society Transactions
    Issue number1
    Publication statusPublished - 2011 Feb 1


    • Bradyrhizobium japonicum
    • Denitrification
    • Haemoglobin
    • Nitric oxide
    • Nodule
    • Soya bean

    ASJC Scopus subject areas

    • Biochemistry

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