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1coz
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(New page: 200px<br /><applet load="1coz" size="450" color="white" frame="true" align="right" spinBox="true" caption="1coz, resolution 2.00Å" /> '''CTP:GLYCEROL-3-PHOSP...)
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Revision as of 10:31, 20 November 2007
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CTP:GLYCEROL-3-PHOSPHATE CYTIDYLYLTRANSFERASE FROM BACILLUS SUBTILIS
Overview
BACKGROUND: The formation of critical intermediates in the biosynthesis of, lipids and complex carbohydrates is carried out by cytidylyltransferases, which utilize CTP to form activated CDP-alcohols or CMP-acid sugars plus, inorganic pyrophosphate. Several cytidylyltransferases are related and, constitute a conserved family of enzymes. The eukaryotic members of the, family are complex enzymes with multiple regulatory regions or repeated, catalytic domains, whereas the bacterial enzyme, CTP:glycerol-3-phosphate, cytidylyltransferase (GCT), contains only the catalytic domain. Thus, GCT, provides an excellent model for the study of catalysis by the eukaryotic, cytidylyltransferases. RESULTS: The crystal structure of GCT from Bacillus, subtilis has been determined by multiwavelength anomalous diffraction, using a mercury derivative and refined to 2.0 A resolution (R(factor), 0.196; R(free) 0.255). GCT is a homodimer; each monomer comprises an, alpha/beta fold with a central 3-2-1-4-5 parallel beta sheet. Additional, helices and loops extending from the alpha/beta core form a bowl that, binds substrates. CTP, bound at each active site of the homodimer, interacts with the conserved (14)HXGH and (113)RTXGISTT motifs. The dimer, interface incorporates part of a third motif, (63)RYVDEVI, and includes, hydrophobic residues adjoining the HXGH sequence. CONCLUSIONS: Structure, superpositions relate GCT to the catalytic domains from class I, aminoacyl-tRNA synthetases, and thus expand the tRNA synthetase family of, folds to include the catalytic domains of the family of, cytidylyltransferases. GCT and aminoacyl-tRNA synthetases catalyze, analogous reactions, bind nucleotides in similar U-shaped conformations, and depend on histidines from analogous HXGH motifs for activity. The, structural and other similarities support proposals that GCT, like the, synthetases, catalyzes nucleotidyl transfer by stabilizing a pentavalent, transition state at the alpha-phosphate of CTP.
About this Structure
1COZ is a Single protein structure of sequence from Bacillus subtilis with CTP as ligand. Active as Glycerol-3-phosphate cytidylyltransferase, with EC number 2.7.7.39 Full crystallographic information is available from OCA.
Reference
A prototypical cytidylyltransferase: CTP:glycerol-3-phosphate cytidylyltransferase from bacillus subtilis., Weber CH, Park YS, Sanker S, Kent C, Ludwig ML, Structure. 1999 Sep 15;7(9):1113-24. PMID:10508782
Page seeded by OCA on Tue Nov 20 12:38:15 2007
