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为研究毛白杨蔗糖合酶PtSS3基因的表达模式以及PtSS3蛋白的结构和功能,采用RT-PCR技术,以毛白杨叶片总RNA逆转录的cDNA为模板进行PCR扩增,获得毛白杨PtSS3的基因序列,测序结果显示该基因序列全长为2 474 bp,包括一个完整的阅读框,编码823个氨基酸。通过NCBI的Blast检索和Bioediter软件分析,Pt SS3与毛果杨、胡杨、橡胶树、麻风树的核酸和氨基酸序列的同源性分别达到85%~98%和87%~98%,氨基酸序列中包含有蔗糖合酶和糖基转移酶两个保守的功能域。运用蛋白三维结构预测软件分析显示,PtSS3编码的蛋白共含有37个α-螺旋、27个β-折叠和62个无规卷曲结构,Prot Scale工具分析结果表明该蛋白属于亲水性蛋白。进化分析显示该基因家族在进化过程中分化为单子叶组、双子叶组、单双子叶1组和单双子叶2组4个分支,PtSS3蛋白属于单双子叶1组。进一步的qRT-PCR分析结果表明,PtSS3在毛白杨根、茎、叶及雌雄花芽组织中均呈现组成型表达模式。根据对同源蛋白的功能研究推测,PtSS3可能与在源库组织的韧皮部装载过程中和卸载后蔗糖代谢的能量提供关系密切,并且可能在光合作用的碳分配过程中同样发挥着重要的作用;PtSS3蛋白与其他家族成员保持保守性的同时,又有不可代替性。
In order to study the expression pattern of PtSS3 gene and the structure and function of PtSS3 protein in Populus tomentosa, RT-PCR was used to amplify the PtSS3 gene of Populus tomentosa The full length of the gene was 2 474 bp, including a complete reading frame encoding 823 amino acids. The nucleotide and amino acid sequences of Pt SS3 and Populus tomentosa, Populus euphratica, Rubber tree and Jatropha curcas were 85% ~ 98% and 87% ~ 98% homology with the NCBI Blast search and Bioediter software respectively. The amino acid sequence of Pt SS3 contained There are two conserved domains of sucrose synthase and glycosyltransferase. Analysis of protein three-dimensional structure prediction software showed that PtSS3 protein contained 37 α-helices, 27 β-sheets and 62 random coils. Prot Scale analysis indicated that the protein was a hydrophilic protein. Phylogenetic analysis showed that the gene family was divided into monocotyledon group, dicotyledon group, monocotyledonous group 1 and monocotyledonous dicotyledon 2 group 4 clades during evolution. Further qRT-PCR analysis showed that PtSS3 showed a constitutive expression pattern in root, stem, leaf and male and female flower bud tissues. According to the functional studies of homologous proteins, PtSS3 may be closely related to the energy of sucrose metabolism during phloem loading and unloading, and may also play an important role in photosynthesis carbon distribution. PtSS3 protein and other family members remain conservative at the same time, there are irreplaceable.