Jiang Huawu, Dian Weimin, Liu Feiyang, Wu Ping
State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, 310029 Hangzhou, PR China.
Planta. 2004 Apr;218(6):1062-70. doi: 10.1007/s00425-003-1189-y. Epub 2004 Jan 23.
Three starch synthase (SS) genes, OsSSII-1, OsSSII-2 and OsSSII-3, were identified in rice (Oryza sativa L.) and localized to chromosomes 10, 2 and 6, respectively. The three OsSSII full-length cDNAs were cloned, and the predicted amino acid sequences were found to share 52-73% similarity with other members of the plant SSII family. The SS activity of each OsSSII was confirmed by expression and enzyme activity assay in Escherichia coli. Expression profile analysis revealed that OsSSII-1 was expressed in endosperms, leaves and roots; OsSSII-2 was mainly expressed in leaves, while OsSSII-3 was mainly expressed in endosperms. Similar to the OsSSI proteins, the OsSSII-2 and OsSSII-3 proteins were found in the soluble as well as the starch-granule-bound fractions in rice. The roles of the OsSSII proteins in starch biosynthesis in rice and the evolutionary relationships of the genes encoding monocotyledonous and dicotyledonous class-II SS enzymes are discussed.
在水稻（Oryza sativa L.）中鉴定出三个淀粉合酶（SS）基因，即OsSSII - 1、OsSSII - 2和OsSSII - 3，它们分别定位于第10、2和6号染色体上。克隆了这三个OsSSII的全长cDNA，并发现预测的氨基酸序列与植物SSII家族的其他成员具有52 - 73%的相似性。通过在大肠杆菌中的表达和酶活性测定证实了每个OsSSII的SS活性。表达谱分析表明，OsSSII - 1在胚乳、叶片和根中表达；OsSSII - 2主要在叶片中表达，而OsSSII - 3主要在胚乳中表达。与OsSSI蛋白类似，在水稻中发现OsSSII - 2和OsSSII - 3蛋白存在于可溶性部分以及淀粉颗粒结合部分中。本文讨论了OsSSII蛋白在水稻淀粉生物合成中的作用以及编码单子叶和双子叶II类SS酶的基因的进化关系。
