1fsi | pdb_00001fsi
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: appr>p]]
Page seeded by OCA on Thu Feb 21 12:42:08 2008
