橡胶树半胱氨酸蛋白酶基因HbCP3的克隆与表达特性分析

半胱氨酸蛋白酶是一类重要蛋白水解酶,其广泛参与植物的生长发育及各种生物与非生物胁迫的应答。根据EST序列信息设计引物,从橡胶树的根中分离到1条1 056 bp的c DNA。该序列包含1个1 023 bp的开放阅读框(ORF),13 bp的5'UTR和20 bp的3'UTR。ORF预测编码340个氨基酸,相对分子质量为37 350,等电点为5.24,属于液泡定位的分泌型蛋白。该蛋白含有1个Inhibitor_I29和1个Peptidase_C1A结构域,可归为木瓜蛋白酶C1家族。该蛋白与蓖麻(Ricinus communis)和杨树(Populus trichocarpa)中同源蛋白的相似性都在80%以上,将基因命名为Hb CP3。表达分析显示,在橡胶树的根、树皮、木质部、芽、叶片、叶柄和乳管等组织中,基因仅在根中表达。

Molecular cloning and expression analysis on cysteine proteinase gene (HbCP3) from rubber tree (Hevea brasiliensis Muell.Arg.)

Cysteine proteinases (CPs), a type of important hydrolysis proteases, have played an essential role in plant growth and in response to biotic or abiotic stresses. Based on the available EST sequence, a 1 056 bp cDNA named by HbCP3 was segregated out by using specific primers from root tissues of rubber tree (Hevea brasiliensis Muell. Arg.). The cDNA contained a length of 1 023 bp ORF (open reading frame), 13 bp 5'' UTR and 20 bp 3'' UTR. Sequence analysis suggested that HbCP3 had a deduced code of 340 amino acids with a theoretical molecular weight (Mw) of 37 350 and with isolectric point (pI) of 5.24, and it belonged to a secretory protein located in vacuoles; The protein, containing one Inhibitor_I29 domain and one Peptidase_C1A domain, could be classified into the papain C1 family; Since the protein shared more than 80% similarity with its homologs Ricinus communis and Populus trichocarpa, it was hence named by HbCP3. Results of the expression analysis showed that among in all tissues, i.e., root, bark, xylem, bud, leaf, petiole and laticifer, HbCP3 only exhibited in root.