Structural highlights
FunctionCPT_STRVP Inactivates chloramphenicol by catalyzing the transfer of the gamma-phosphate of ATP to the antibiotic's C-3' hydroxyl group. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedChloramphenicol (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. 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[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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