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

描述（由申请人提供）：转移RNA是翻译的核心，去除3'尾链是tRNA成熟的核心。tRNase Z是trna前3'加工内切酶，在细菌和古细菌中以短形式（tRNase ZS）编码，而在真核生物中以长形式（tRNase ZL）编码。作为一种功能性的同二聚体，tRNase ZS需要一个广泛的二聚体界面，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，使其半独立地进化，从而使人类tRNase ZL的催化效率比tRNase ZS高约1700倍。tRNase ZL净化并可能作为单体起作用。tRNase ZL的氨基和羧基结构域由~70个残基柔性链连接。同源二聚体蛋白串联复制产生的束缚结构域可能是常见的，tRNase ZL说明了这种进化主题的好处。绳子的灵活性也可以解释tRNase ZL结晶失败的原因。我们打算表达和结晶tRNase ZL +/-系链的氨基和羧基结构域，并解析它们的结构。这些结构域的成功将指导全长tRNase ZL的结晶。作为结构域策略的补充，tRNase ZL- trna复合物的形成可以稳定柔性区域，从而实现全长tRNase ZL的结晶。

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.