Kumaran Desigan, Eswaramoorthy Subramaniam, Studier F William, Swaminathan Subramanyam
Biology Department, Brookhaven National Laboratory, Upton, NY 11973, USA.
Protein Sci. 2005 Mar;14(3):719-26. doi: 10.1110/ps.041132005.
Appr-1''-pase, an important and ubiquitous cellular processing enzyme involved in the tRNA splicing pathway, catalyzes the conversion of ADP-ribose-1''monophosphate (Appr-1''-p) to ADP-ribose. The structures of the native enzyme from the yeast and its complex with ADP-ribose were determined to 1.9 A and 2.05 A, respectively. Analysis of the three-dimensional structure of this protein, selected as a target in a structural genomics project, reveals its putative function and provides clues to the catalytic mechanism. The structure of the 284-amino acid protein shows a two-domain architecture consisting of a three-layer alphabetaalpha sandwich N-terminal domain connected to a small C-terminal helical domain. The structure of Appr-1''-pase in complex with the product, ADP-ribose, reveals an active-site water molecule poised for nucleophilic attack on the terminal phosphate group. Loop-region residues Asn 80, Asp 90, and His 145 may form a catalytic triad.
Appr-1''-磷酸酶是一种参与tRNA剪接途径的重要且普遍存在的细胞加工酶,它催化ADP-核糖-1''-单磷酸(Appr-1''-p)转化为ADP-核糖。已分别确定来自酵母的天然酶及其与ADP-核糖的复合物的结构分辨率为1.9埃和2.05埃。作为结构基因组学项目中的一个靶标,对该蛋白质三维结构的分析揭示了其假定功能,并为催化机制提供了线索。这种由284个氨基酸组成的蛋白质的结构显示出一种双结构域架构,由一个连接到小的C端螺旋结构域的三层αββα三明治N端结构域组成。Appr-1''-磷酸酶与产物ADP-核糖形成复合物的结构揭示了一个准备对末端磷酸基团进行亲核攻击的活性位点水分子。环区残基Asn 80、Asp 90和His 145可能形成一个催化三联体。