Characterization of starch synthase I and II expressed in early developing seeds of kidney bean (Phaseolus vulgaris L.)

• Published in: Bioscience, biotechnology, and biochemistry biotechnology, and biochemistry, 2004-09, Vol.68 (9), p.1949-1960
• Main Authors: Senoura, T. (Hokkaido Univ., Sapporo (Japan)), Isono, N, Yoshikawa, M, Asao, A, Hamada, S, Watanabe, K, Ito, H, Matsui, H
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; amylopectin; Biological and medical sciences; Cloning, Molecular; DNA; ESCHERICHIA COLI; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation; Gene Expression Regulation, Developmental; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; IMMUNOBLOTTING; kidney bean (Phaseolus vulgaris L.); KIDNEY BEANS; kinetics; LIGASES; Molecular Sequence Data; Phaseolus - enzymology; Phylogeny; Plant Proteins - genetics; PURIFICATION; RECOMBINATION; RNA, Plant - analysis; Seeds - enzymology; Sequence Alignment; STARCH; Starch - biosynthesis; starch synthase; Starch Synthase - genetics
• ISSN: 0916-8451; 1347-6947
• DOI: 10.1271/bbb.68.1949

Plant starch synthase (SS) contributes to the elongation of glucan chains during starch biosynthesis and hence plays an essential role in determining the fine structure of amylopectin. To elucidate the role of SS activity in the formation of amylopectin in kidney bean (Phaseolus vulgaris L.), a study was undertaken to isolate cDNA clones for SS and to characterize the enzymatic properties of the coded recombinant enzymes. Two SS cDNAs, designated pvss1 and pvss21, which were isolated from early developing seeds, encoded SSI and SSII (designated PvSSI and PvSSII1) that displayed significant identity (more than 65%) with other SSI and SSII members, respectively. RNA gel blot analysis indicated that both transcripts accumulate in leaves and developing seeds at the early stage. Immunoblot analysis with antisera raised against both recombinant proteins (rPvSSI and rPvSSII-1) showed that the accumulation of both proteins parallels the gene expression profiles, although both were detectable only in starch-granule fractions. Recombinant enzymes expressed by Escherichia coli cells showed distinct chainlength specificities for the extension of glucan chains. Our results suggest that these SS isozymes for synthesis of transitory starch are also responsible for synthesis of storage starch in early developing seeds of kidney bean.