1fsi
From Proteopedia
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CRYSTAL STRUCTURE OF CYCLIC NUCLEOTIDE PHOSPHODIESTERASE OF APPR>P FROM ARABIDOPSIS THALIANA
Overview
The crystal structure of the cyclic phosphodiesterase (CPDase) from, Arabidopsis thaliana, an enzyme involved in the tRNA splicing pathway, was, determined at 2.5 A resolution. CPDase hydrolyzes ADP-ribose 1",2"-cyclic, phosphate (Appr>p), a product of the tRNA splicing reaction, to the, monoester ADP-ribose 1"-phosphate (Appr-1"p). The 181 amino acid protein, shows a novel, bilobal arrangement of two alphabeta modules. Each lobe, consists of two alpha-helices on the outer side of the molecule, framing a, three- or four-stranded antiparallel beta-sheet in the core of the, protein. The active site is formed at the interface of the two beta-sheets, in a water-filled cavity involving residues from two H-X-T/S-X motifs., This previously noticed motif participates in coordination of a sulfate, ion. A solvent-exposed surface loop (residues 100-115) is very likely to, play a flap-like role, opening and closing the active site. Based on the, crystal structure and on recent mutagenesis studies of a homologous CPDase, from Saccharomyces cerevisiae, we propose an enzymatic mechanism that, employs the nucleophilic attack of a water molecule activated by one of, the active site histidines.
About this Structure
1FSI is a Single protein structure of sequence from Arabidopsis thaliana with SO4 as ligand. Full crystallographic information is available from OCA.
Reference
Structure and mechanism of activity of the cyclic phosphodiesterase of Appr>p, a product of the tRNA splicing reaction., Hofmann A, Zdanov A, Genschik P, Ruvinov S, Filipowicz W, Wlodawer A, EMBO J. 2000 Nov 15;19(22):6207-17. PMID:11080166[[Category: 2-cyclic phosphate]][[Category: adp-ribose 1]] [[Category: appr>p]]
Page seeded by OCA on Tue Nov 20 15:14:27 2007
