Carbohydrate-binding module of a rice endo-β-1,4-glycanase, OsCel9A, expressed in auxin-induced lateral root primordia, is post-translationally truncated

Kouki Yoshida, Nobuyuki Imaizumi, Satoshi Kaneko, Yasushi Kawagoe, Akemi Tagiri, Hiroshi Tanaka, Kazuhiko Nishitani, Kozo Komae

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    19 Citations (Scopus)

    Abstract

    We report the cloning of a glycoside hydrolase family (GHF) 9 gene of rice (Oryza sativa L. cv. Sasanishiki), OsCel9A, corresponding to the auxin-induced 51 kDa endo-1,4-β-glucanase (EGase). This enzyme reveals a broad substrate specificity with respect to sugar backbones (glucose and xylose) in β-1,4-glycans of type II cell wall. OsCel9A encodes a 640 amino acid polypeptide and is an ortholog of TomCel8, a tomato EGase containing a carbohydrate-binding module (CBM) 2 sequence at its C-terminus. The expression of four rice EGase genes including OsCel9A showed different patterns of organ specificity and responses to auxin. OsCel9A was preferentially expressed during the initiation of lateral roots or subcultured root calli, but was hardly expressed during auxin-induced coleoptile elongation or in seed calli, in contrast to OsCel9D, a KORRIGAN (KOR) homolog. In situ localization of OsCel9A transcripts demonstrated that its expression was specifically up-regulated in lateral root primordia (LRP). Northern blotting analysis showed the presence of a single product of OsCel9A. In contrast, both mass spectrometric analyses of peptide fragments from purified 51 kDa EGase proteins and immunogel blot analysis of EGase proteins in root extracts using two antibodies against internal peptide sequences of OsCel9A revealed that the entire CBM2 region was post-translationally truncated from the 67 kDa nascent protein to generate 51 kDa EGase isoforms. Analyses of auxin concentration and time course dependence of accumulation of two EGase isoforms suggested that the translation and post-translational CBM2 truncation of the OsCel9A gene may participate in lateral root development.

    Original languageEnglish
    Pages (from-to)1555-1571
    Number of pages17
    JournalPlant and Cell Physiology
    Volume47
    Issue number11
    DOIs
    Publication statusPublished - 2006 Nov

    Keywords

    • Auxin
    • Carbohydrate-binding module family 2
    • Glycoside hydrolase family 9
    • Lateral root formation
    • Processing
    • Rice

    ASJC Scopus subject areas

    • Physiology
    • Plant Science
    • Cell Biology

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