Identification of Two Plastid-Targeted β-Amylases in Rice

• Published in: Plant production science Vol. 14; no. 4; pp. 318 - 324
• Main Authors: Hirano, Tatsuya, Takahashi, Yusuke, Fukayama, Hiroshi, Michiyama, Hiroyasu
• Format: Journal Article
• Language: English
• Published: Tokyo Taylor & Francis 2011; Crop Science Society of Japan; Taylor & Francis Ltd; Taylor & Francis Group
• Subjects: Agronomy. Soil science and plant productions; Amylases; Biological and medical sciences; Chloroplasts; E coli; Epidermis; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Genes; Isoforms; Leaves; Oryza sativa L; Plastids; Proteins; Rice; Seeds; Sheaths; Starch metabolism; ß-Amylase; β-Amylase; Plant production; Starch metabolism; Monocotyledones; Enzyme; Starch; Oryza sativa L; Plastid; Metabolism; Cereal crop; Glycosylases; Oryza sativa; β-Amylase; Gramineae; Glycosidases; Angiospermae; Hydrolases; Spermatophyta
• ISSN: 1343-943X; 1349-1008
• DOI: 10.1626/pps.14.318

In order to identify β-amylase isoforms acting inside plastids in rice (Oryza sativa L.), in the rice genome database we searched the genes predicted to encode β-amylase-like proteins, and designated them OsBAM1−9. OsBAM1, OsBAM7, and OsBAM9 genes were mainly expressed in germinating seeds and developing caryopses. In contrast, the transcripts of OsBAM2, OsBAM3, OsBAM4 and OsBAM5, which have a putative chloroplast transit peptide in their N-terminal regions, were mainly detected in leaf blades, leaf sheaths and internodes after heading. Soluble protein fractions prepared from Escherichia coli containing recombinant OsBAM2 and OsBAM3 proteins had significant β-amylase activity. Furthermore, OsBAM2-GFP and OsBAM3-GFP fusion proteins introduced into epidermis of Allium cepa scaly bulb were localized to the plastids. These results strongly suggest that OsBAM2 and OsBAM3 are plastid-targeted active β-amylase.