1qhs
From Proteopedia
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| , resolution 2.8Å | |||||||
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| Ligands: | , | ||||||
| Related: | 1QHN, 1QHS, 1QHX, 1QHY
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| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
CHLORAMPHENICOL PHOSPHOTRANSFERASE IN COMPLEX WITH CHLORAMPHENICOL FROM STREPTOMYCES VENEZUELAE
Overview
Chloramphenicol (Cm), produced by the soil bacterium Streptomyces venezuelae, is an inhibitor of bacterial ribosomal peptidyltransferase activity. The Cm-producing streptomycete modifies the primary (C-3) hydroxyl of the antibiotic by a novel Cm-inactivating enzyme, chloramphenicol 3-O-phosphotransferase (CPT). Here we describe the crystal structures of CPT in the absence and presence of bound substrates. The enzyme is dimeric in a sulfate-free solution and tetramerization is induced by ammonium sulfate, the crystallization precipitant. The tetrameric quaternary structure exhibits crystallographic 222 symmetry and has ATP binding pockets located at a crystallographic 2-fold axis. Steric hindrance allows only one ATP to bind per dimer within the tetramer. In addition to active site binding by Cm, an electron-dense feature resembling the enzyme's product is found at the other subunit interface. The structures of CPT suggest that an aspartate acts as a general base to accept a proton from the 3-hydroxyl of Cm, concurrent with nucleophilic attack of the resulting oxyanion on the gamma-phosphate of ATP. Comparison between liganded and substrate-free CPT structures highlights side chain movements of the active site's Arg136 guanidinium group of >9 A upon substrate binding.
About this Structure
1QHS is a Single protein structure of sequence from Streptomyces venezuelae. Full crystallographic information is available from OCA.
Reference
The crystal structures of chloramphenicol phosphotransferase reveal a novel inactivation mechanism., Izard T, Ellis J, EMBO J. 2000 Jun 1;19(11):2690-700. PMID:10835366
Page seeded by OCA on Sun Mar 30 23:13:45 2008
