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可溶性酸性转化酶(SAI)是甜高粱蔗糖代谢关键调控酶。本研究利用RT-PCR的方法,克隆得到了甜高粱SAI-1基因cDNA全长序列(Genbank No.:KF921516),并利用生物信息学方法对其结构以及蛋白功能进行了分析。结果表明:克隆得到的SAI-1 cDNA序列长2 345 bp,包含一个2 025 bp的编码区、210 bp的5’非翻译区和110 bp的3’非翻译区。其编码674个氨基酸蛋白,预测分子量为73.42 kD,等电点为5.76,蛋白序列含有一个完整的糖基水解酶家族32结构域,具有水解蔗糖的作用。甜高粱茎秆中的SAI-1表达水平在拔节和抽穗期较高,而在开花期后的各个时期均处于较低水平,这与甜高粱糖分积累呈负相关。本研究结果为进一步研究SAI-1基因调控甜高粱糖分含量的分子机制奠定了基础。
Soluble acid invertase (SAI) is a key regulator of sucrose metabolism in sweet sorghum. In this study, the full-length cDNA of SAI-1 gene was cloned by RT-PCR (Genbank No.:KF921516), and its structure and protein function were analyzed by bioinformatics methods. The results showed that the cloned cDNA sequence of SAI-1 was 2 345 bp long and contained a 2025 bp coding region, a 210 bp 5 ’untranslated region and a 110 bp 3’ untranslated region. It encodes a protein of 674 amino acids with a predicted molecular mass of 73.42 kD and an isoelectric point of 5.76. The protein sequence contains a complete 32 family of glycosyl hydrolases, which has the effect of hydrolyzing sucrose. The expression level of SAI-1 in sweet sorghum stalks was higher at jointing and heading stages, but lower at all stages after anthesis, which was negatively correlated with the sugar accumulation in sweet sorghum. The results of this study lay the foundation for the further study on the molecular mechanism of SAI-1 gene regulating sugar content in sweet sorghum.