1fsi
From Proteopedia
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| , resolution 2.50Å | |||||||
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| Coordinates: | save as pdb, mmCIF, xml | ||||||
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. 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: appr>p]]
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