1qhs
From Proteopedia
(New page: 200px<br /><applet load="1qhs" size="450" color="white" frame="true" align="right" spinBox="true" caption="1qhs, resolution 2.8Å" /> '''CHLORAMPHENICOL PHOSP...) |
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| - | [[Image:1qhs.jpg|left|200px]]<br /><applet load="1qhs" size=" | + | [[Image:1qhs.jpg|left|200px]]<br /><applet load="1qhs" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1qhs, resolution 2.8Å" /> | caption="1qhs, resolution 2.8Å" /> | ||
'''CHLORAMPHENICOL PHOSPHOTRANSFERASE IN COMPLEX WITH CHLORAMPHENICOL FROM STREPTOMYCES VENEZUELAE'''<br /> | '''CHLORAMPHENICOL PHOSPHOTRANSFERASE IN COMPLEX WITH CHLORAMPHENICOL FROM STREPTOMYCES VENEZUELAE'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Chloramphenicol (Cm), produced by the soil bacterium Streptomyces | + | 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== | ==About this Structure== | ||
| - | 1QHS is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Streptomyces_venezuelae Streptomyces venezuelae] with SO4 and CLM as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http:// | + | 1QHS is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Streptomyces_venezuelae Streptomyces venezuelae] with <scene name='pdbligand=SO4:'>SO4</scene> and <scene name='pdbligand=CLM:'>CLM</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1QHS OCA]. |
==Reference== | ==Reference== | ||
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[[Category: phosphorylation]] | [[Category: phosphorylation]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:39:42 2008'' |
Revision as of 12:39, 21 February 2008
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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 with and as ligands. 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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