Domain Structure of tRNase ZL, the Long Form of tRNase Z

描述(申请人提供)：转移RNA是翻译的中心，3‘拖尾的去除是tRNA成熟的中心。TRNase Z是tRNA3‘加工前的内切酶，在细菌和古生菌中以短形式(TRNase ZS)编码，以长形式(TRNase ZL)编码，仅在真核生物中存在。作为一个功能正常的同源二聚体，tRNaseZS需要一个广泛的二聚体接口，以便亚基能够可靠地找到彼此。TRNase ZL起源于tRNase ZS的串联复制，它释放了tRNase ZL的氨基和羧基结构域，使其半独立进化，使人tRNase ZL的催化效率比tRNase ZS高约1700倍。TRNase ZL可提纯，并可能作为单体发挥作用。TRNase ZL的氨基和羧基结构域由~70个残基的柔性系链连接。由于同源二聚体蛋白质的串联复制而产生的系链结构域可能是常见的，tRNaseZL说明了这一进化主题的好处。系绳的灵活性也解释了tRNaseZL结晶不成功的原因。我们建议表达和结晶tRNase ZL+/-系绳的氨基和羧基结构域，并解决它们的结构。结构域的成功将指导全长tRNaseZL的结晶。作为结构域策略的补充，tRNase ZL-tRNA复合体的形成可以稳定柔性区域，允许全长tRNase ZL的结晶。 公共卫生相关性：tRNase Z已被认为是人类前列腺癌的易感基因。人类线粒体tRNAs的许多致病相关突变会影响tRNA的代谢，包括tRNase Z反应。TRNase ZS的串联复制导致了tRNase ZL的产生，包括柔性系链，是进化和酶学中的一个重要基序。

DESCRIPTION (provided by applicant): Transfer RNA is central to translation and removal of the 3' trailer is central to tRNA maturation. tRNase Z, the pre-tRNA 3' processing endonuclease, is encoded in a short form (tRNase ZS) in bacteria and archaea and in a long form (tRNase ZL) found only in eukaryotes. As a functioning homodimer, tRNase ZS requires an extensive dimer interface for the subunits to reliably find each other. tRNase ZL originated as a tandem duplication of tRNase ZS which freed the amino and carboxy domains of tRNase ZL to evolve semi-independently, contributing to the ~1,700X greater catalytic efficiency of human tRNase ZL over tRNase ZS. tRNase ZL purifies and presumably functions as a monomer. The amino and carboxy domains of tRNase ZL are linked by a ~70 residue flexible tether. Tethered domains arising from tandem duplications of homodimer proteins may be common and tRNase ZL illustrates the benefits of this evolutionary theme. Flexibility of the tether could also explai the lack of success at crystallizing tRNase ZL. We propose to express and crystallize the amino and carboxy domains of tRNase ZL +/- tether and solve their structures. Success with the domains will guide crystallization of full length tRNase ZL. Complementing domain strategy, formation of a tRNase ZL-tRNA complex could stabilize flexible regions, allowing crystallization of full length tRNase ZL. PUBLIC HEALTH RELEVANCE: tRNase Z has been suggested to be a human prostate cancer susceptibility gene. Numerous pathogenesis-related mutations in human mitochondrial tRNAs affect tRNA metabolism including the tRNase Z reaction. The tandem duplication of tRNase ZS that gave rise to tRNase ZL, including the flexible tether, is an important motif in evolution and enzymology.