野生香蕉几丁质酶抗冻蛋白基因(Chi Ⅰ2)的克隆及分析

Cloning and Sequence Analyzing of a Chitinase Anti-freeze Protein Gene (Chi Ⅰ2) from the Wild Banana

以4℃处理64 h的三明野生香蕉叶片为材料,采用RT-PCR结合RACE方法,获得了几丁质酶抗冻蛋白基因,该基因cDNA全长为1097 bp,3'UTR为149 bp,3'末端poly(A)尾长17 bp,命名为ChiⅠ2(基因登录号:FJ222750)。野生香蕉ChiⅠ2蛋白有两个几丁质结合区,这可能是该基因具有抗冻活性与抗病菌活性的主要功能性区域。将ChiⅠ2基因与已克隆得到的ChiⅠ1基因相比,ChiⅠ2基因的3'非编码区缺失了28 bp的碱基序列,这部分缺失的序列可能调控着几丁质酶抗冻蛋白基因的表达。

Full length cDNA （1097 bp） of the chitinase gene was cloned from the wild banana leaves from Sanming City under cold stress （4 ℃ 64 h） by RT-PCR combined with RACE. It contained 149 bp in the 3′UTR and 3′-end including 17 bp poly （A） tail,named as ChiⅠ2 （GenBank： FJ222750）. The results which were analyzed by using bioinformatic methods showed that the protein was acidic hydrophilic protein with transmembrane domain and mainly located outside. They belonged to the chitinases family 19,chitinase class Ⅰ. ChiⅠ2 contained two chitin-binding domains,which may be the main function domains combining antifreeze activity with antivirus activity. The structure of ChiⅠ2 gene of the wild banana from Samming City was similar to chitinase antifreeze protein which had been reported in the world. Accordingly,ChiⅠ2 gene was preliminary inferred to as a chitinase-AFP gene.