1QHN
CHLORAMPHENICOL PHOSPHOTRANSFERASE FROM STREPTOMYCES VENEZUELAE
Summary for 1QHN
| Entry DOI | 10.2210/pdb1qhn/pdb |
| Related | 1QHS 1QHX 1QHY |
| Descriptor | CHLORAMPHENICOL PHOSPHOTRANSFERASE, SULFATE ION (3 entities in total) |
| Functional Keywords | kinase, antibiotic resistance, phosphorylation, mononucleotide binding fold, transferase |
| Biological source | Streptomyces venezuelae |
| Total number of polymer chains | 1 |
| Total formula weight | 19211.80 |
| Authors | Izard, T. (deposition date: 1999-05-23, release date: 2000-06-07, Last modification date: 2024-10-16) |
| Primary citation | Izard, T.,Ellis, J. The Crystal Structures of Chloramphenicol Phosphotransferase Reveal a Novel Inactivation Mechanism Embo J., 19:2690-2700, 2000 Cited by PubMed Abstract: 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. PubMed: 10835366DOI: 10.1093/emboj/19.1.1 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (2.7 Å) |
Structure validation
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