细菌和人短型tRNase Z^S与粟酒裂殖酵母长型tRNase Z^L功能保守性研究  

Functional Conservation Between Bacterial and Human tRNase Z^S and Schizosaccharomyces pombe tRNase Z^L

作　　者：刘金玉[1] 谷陈建[1] 杨杰[1] 严煜艳[1] 黄鹰[1] 

机构地区：[1]南京师范大学生命科学学院,中国江苏南京210023

出　　处：《生命科学研究》2013年第5期387-393,405,共8页Life Science Research

基　　金：国家自然科学基金资助项目(2011104GZ30018);国家基础科学人才培养基金资助项目(J1103507;J1210025);江苏省大学生创新创业训练计划资助项目

摘　　要：tRNase Z是一种参与tRNA前体3'末端加工的核酸内切酶,根据氨基酸残基数目分为长型(tRNase ZL)和短型(tRNase ZS)两类.细菌只有短型,而真核生物既可以有短型也可以有长型,并且绝大部分真核生物只有一个长型.为了研究短型tRNase Z和长型tRNase Z的功能保守性,分别构建表达编码枯草芽孢杆菌(Bacillus subtilis)短型tRNase Z(BsuTrz1)、人短型tRNase Z(ELAC1)以及海栖热袍菌(Thermotoga maritima)短型tRNase Z(TmaTrz1)的酵母低表达载体,并转化tRNase ZL温敏型粟酒裂殖酵母(Schizosaccharomyces pombe)进行互补救活实验.结果显示,与粟酒裂殖酵母tRNase ZL(SpTrz1)相比,ELAC1能在37℃完全救活酵母tRNase ZL温敏型菌株,而BsuTrz1的救活能力略弱.但具有不同底物特异性的TmaTrz1则完全不能救活.此外,催化活性受损的ELAC1组氨酸模体突变体(ELAC1-H62A和ELAC1-H64A)救活酵母tRNase ZL温敏型菌株的能力极大受损.这些结果表明,枯草芽孢杆菌和人的tRNase ZS能替代粟酒裂殖酵母的tRNase ZL,并且这些蛋白具有功能保守性.这些实验进一步支持了长型tRNase Z基因是由短型tRNase Z基因复制后序列进化形成的观点.tRNase Z is the tRNA 3＇-end processing endonuclease that removes the 3＇-trailer sequences from precursor tRNAs. Based on the size of the amino acid sequence, tRNase Z can be divided in short （tRNase Zs） and long （tRNase ZL） forms. Bacteria has only tRNase Zs, whereas eukaryotes can have both tRNase Zs and tRNase ZL and the majority of eukaryotes have one tRNase ZL. To study the functional conservation be- tween tRNase Zs and tRNase ZL, we constructed the expression vectors for tRNase Zs from Bacillus subtilis （BsuTrzl）, Thermotoga maritima （TmaTrzl） and humans （ELAC1） and transformed them into a tRNase ZL- temperature sensitivity mutant strain of the fission yeast Schizosaccharomyces pombe. Compared to S. pombe tRNase ZL （SpTrzl）, ELAC1 and, to a lesser extant, BsuTrzl could restore the normal growth of the mutant strain at 37 ℃, whereas TmaTrzl, which has the different substrate specificity, could not rescue the tempera- ture sensitive mutant. In addition, the ability of catalytically inactive mutants of ELAC1 （ELAC1-H62A and ELAC1-H64A） to rescue the temperature sensitive mutant was compromised. These results suggest that BsuTrzl and ELAC1 can substitute for SpTrzl and that these proteins are functionally conserved. These re- suits also support the idea that tRNase ZL arises from gene duplication of tRNase Zs and further sequence di- vergence.

关 键 词：tRNase Z 粟酒裂殖酵母 温度敏感型 功能保守性 

分 类 号：Q78[生物学—分子生物学]