摘要
糖苷生物碱(SGAs)是一类存在于茄科植物和百合科植物的重要次生代谢物,与植物抗逆性和产品品质有密切关系,同时在医药上具有广泛的药理学活性。茄啶:糖基转移酶(SGT)为SGAs合成代谢途径末端关键酶,研究其基因结构及其编码的酶蛋白特性,对于调控植物体内SGAs合成及其通过微生物发酵生产SGTs有重要的作用和意义。通过生物信息学分析方法预测3个糖基转移酶cDNA编码的酶蛋白结构和特性。以马铃薯块茎表皮总RNA为模板,采用RT-PCR的方法扩增出3个糖基转移酶(SGT1、SGT2和SGT3)基因片段并克隆到pMDR19-T载体。阳性克隆经PCR鉴定后进行测序,序列分析结果表明,克隆到的sgt1、sgt2和sgt3三个同源的序列片段(1 467～1 518bp),编码488～505个氨基酸;所得序列与GenBank中注册的高等植物SGT酶基因核苷酸序列(U82367.2、DQ 218276.1和DQ 266437)的同源性均在99.12%以上,氨基酸同源性达到99%以上,3个基因都具有UDPG糖基转移酶保守结构域及许多重要功能位点;PI为5.52～5.62。三级结构预测表明,该氨基酸同糖基转移酶单体结构模型相似,都为糖基转移酶家族成员,具有合成类固醇糖苷生物碱的功能,基因序列已注册到Gen-Bank,序列注册号分别为:sgt1,JN695005;sgt2,JN695006;sgt3,HM188447。
The potato steroidal glycoalkaloids（SGAs） is an important secondary metabolites in solanaceae and liliaceae.It is closely related to the antireversion force of plan itselfe and product quality,simultaneously,it has a wide pharmacological activity in pharmacology.Solanidine： UDP-glucosyltransferase（SGT） was the key enzyme of the terminal of SGAs anabolic pathway in Solanum tuberosum.Studying the gene structure and its encoding enzyme protein characteristic plays an important role in the process of the regulation of SGAs synthesis and production of SGTs by microbial fermentation in plant.Analyzing the structure and properties of three enzyme protein encoded by glycosyltransferase cDNA structure and properties by bioinformatics method.Total RNA was extracted from stem of S.tuberosum and three glycoalkaloid synthase gene（SGT1,SGT2 and SGT3） fragment was obtained by reverse transcription polymerase chin reaction（RT-PCR）.It was cloned into pMDR19-T vector and the positive clones identified by PCR were sequenced.Three SGT enzyme gene fragments were gained from stem of S.tuberosum,each of which contains 1 467-1 518 bp and encodes a peptide of 488-505 amino acids.Similarity comparisons show that they share over 99.12% similarity in nucleotide sequence and over 99% similarity in amino acid sequence with those of other plant SGTase gene（U82367.2,DQ 218276.1 and DQ 266437） in GenBank,UDPG glycosyltransferase conserved domain and many important functional sites.the PI=5.52-5.62.The 3D structure of protein was predicted by homology comparative modeling in Swiss-Model,the results showed that the 3D structure of SGT was highly similar to that of the glycosyltransferase,so it was inferred that SGT3 should be a member of glycosyltransferase superfamily that has function of steroidal glycoalkaloid.sgt1,sgt2 and sgt3 similar gene obtained here was rhamnosyl transferase gene,and its sequence was submitted with GenBank： sgt1,No： JN695005;sgt2,No： JN695006;sgt3,No： HM188447.
出处
《草业学报》
CSCD
北大核心
2012年第3期106-116,共11页
Acta Prataculturae Sinica
基金
科技部国家重点基础研究发展计划(973计划)前期项目(2010CB134404)
甘肃省自然科学基金项目(0710RJZA088)资助
