Triticum aestivum puroindolines, two basic cystine-rich seed proteins: cDNA sequence analysis and developmental gene expression

• Published in: Plant molecular biology 1994-04, Vol.25 (1), p.43-57
• Main Authors: Gautier, M.F. (Laboratoire de Biochimie et Biologie Moleculaire des Cereales INRA, Montpellier (France)), Aleman, M.E, Guirao, A, Marion, D, Joudrier, P
• Format: Article
• Language: English
• Subjects: ADN; Amino Acid Sequence; Base Sequence; Biochemistry, Molecular Biology; DNA; DNA - isolation & purification; DNA, Complementary - chemistry; Edible Grain - chemistry; EXPRESION GENICA; EXPRESSION DES GENES; GENE EXPRESSION; Gene Expression Regulation; Life Sciences; Molecular Sequence Data; Plant Proteins - biosynthesis; Plant Proteins - chemistry; Plant Proteins - genetics; Protein Precursors - chemistry; PROTEINAS; PROTEINE; PROTEINS; RNA - isolation & purification; Seeds - genetics; Sequence Homology, Amino Acid; TRIPTOFANO; Triticum - chemistry; Triticum - genetics; Triticum - growth & development; TRITICUM AESTIVUM; TRYPTOPHAN; TRYPTOPHANE
• ISSN: 0167-4412; 1573-5028
• DOI: 10.1007/bf00024197

From a mid-maturation seed cDNA library we have isolated cDNA clones encoding two Triticum aestivum puroindolines. Puroindoline-a and puroindoline-b, which are 55% similar, are basic, cystine-rich and tryptophan-rich proteins. Puroindolines are synthesized as preproproteins which include N- and C-terminal propeptides which could be involved in their vacuolar localization. The mature proteins have a molecular mass of 13 kDa and a calculated isoelectric point greater than 10. A notable feature of the primary structure of puroindolines is the presence of a tryptophan-rich domain which also contains basic residues. A similar tryptophan-rich domain was found within an oat seed protein and a mammalian antimicrobial peptide. The ten cysteine residues of puroindolines are organized in a cysteine skeleton which shows similarity to the cysteine skeleton of other wheat seed cystine-rich proteins. Northern blot analysis showed that puroindoline genes are specifically expressed in T. aestivum developing seeds. No puroindoline transcripts as well as no related genes were detected in Triticum durum. The identity of puroindolines to wheat starch-granule associated proteins is discussed as well as the potential role of puroindolines in the plant defence mechanism.