烟草半胱氨酸蛋白酶抑制剂(CPI)基因家族的克隆及组织表达谱分析

Cloning and tissue expression of cysteine proteinase inhibitor(CPI) gene family in Nicotiana tabacum L.

运用生物信息学方法,结合RT-PCR和SMART RACE技术从烟草(Nicotiana tabacum)中克隆了4个CPI基因的全长cDNA序列,分别命名为NtCPI1、NtCPI2、NtCPI3和NtCPI4,GenBank登陆号分别为KF057988、KF057989、KF057990和KF057991。基因序列分析表明4个基因分别编码98、98、120和123个氨基酸残基的蛋白质,都具有CPI反应位点的保守基序GG、QXVXQ和A/PW,同时具有植物CPI所特有的LARFAV基序,其中NtCPI3和NtCPI4的N端还包含一段27个氨基酸残基组成的信号肽。实时荧光定量PCR试验表明,4个基因的组织表达谱很广,在根、茎、叶和芽组织中都有表达。研究结果为进一步研究半胱氨酸蛋白酶抑制剂在植物中的生理功能奠定了基础。

Full-length cDNAs of fourCPI genes includingNtCPI1、NtCPI2、NtCPI3andNtCPI4were cloned fromNicotiana tabacum L. cv. K326 using RT-PCR and SMART RACE technique. Their sequences were deposited in GenBank with accession number KF057988, KF057989, KF057990 and KF057991. Sequence analysis showed that these four genes were predicted products of 98, 98, 120 and 123 amino acid residues, respectively. In addition to the typical inhibitory motifs, i.e. central signature motif QXVXG, a GG doublet in terminal region, and A/PW residues in C-terminal part. These deduced amino acid sequences contained PhyCys-specific LARFAV-like motif in the N-terminal region, of which a N-terminal signal peptide of 27 residues was found in both NtCPI3 and NtCPI4. Meanwhile, transcripts of these four genes were found in roots, stems, leaves and buds by real-time quantitative PCR, which indicated that they were broadly expressed in tobacco. This study laid foundation for further exploring physiological functions of these cysteine proteinase inhibitor genes in plants.