1coz
From Proteopedia
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| , resolution 2.00Å | |||||||
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| Ligands: | |||||||
| Activity: | Glycerol-3-phosphate cytidylyltransferase, with EC number 2.7.7.39 | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
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. 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 Sun Mar 23 11:24:21 2008
