1qhx
From Proteopedia
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|PDB= 1qhx |SIZE=350|CAPTION= <scene name='initialview01'>1qhx</scene>, resolution 2.5Å | |PDB= 1qhx |SIZE=350|CAPTION= <scene name='initialview01'>1qhx</scene>, resolution 2.5Å | ||
|SITE= | |SITE= | ||
| - | |LIGAND= <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene> and <scene name='pdbligand=ATP:ADENOSINE-5 | + | |LIGAND= <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene> and <scene name='pdbligand=ATP:ADENOSINE-5'-TRIPHOSPHATE'>ATP</scene> |
|ACTIVITY= | |ACTIVITY= | ||
|GENE= | |GENE= | ||
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[[Category: phosphorylation]] | [[Category: phosphorylation]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Mar 23 13:20:39 2008'' |
Revision as of 11:20, 23 March 2008
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| Coordinates: | save as pdb, mmCIF, xml | ||||||
CHLORAMPHENICOL PHOSPHOTRANSFERASE IN COMPLEX WITH ATP 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
1QHX 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
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