1qhn
From Proteopedia
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'''CHLORAMPHENICOL PHOSPHOTRANSFERASE FROM STREPTOMYCES VENEZUELAE''' | '''CHLORAMPHENICOL PHOSPHOTRANSFERASE FROM STREPTOMYCES VENEZUELAE''' | ||
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[[Category: Streptomyces venezuelae]] | [[Category: Streptomyces venezuelae]] | ||
[[Category: Izard, T.]] | [[Category: Izard, T.]] | ||
| - | [[Category: | + | [[Category: Antibiotic resistance]] |
| - | [[Category: | + | [[Category: Kinase]] |
| - | [[Category: | + | [[Category: Mononucleotide binding fold]] |
| - | [[Category: | + | [[Category: Phosphorylation]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 06:17:01 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 03:17, 3 May 2008
CHLORAMPHENICOL PHOSPHOTRANSFERASE 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
1QHN 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 Sat May 3 06:17:01 2008
