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1qhn

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{{STRUCTURE_1qhn| PDB=1qhn | SCENE= }}
{{STRUCTURE_1qhn| PDB=1qhn | SCENE= }}
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'''CHLORAMPHENICOL PHOSPHOTRANSFERASE FROM STREPTOMYCES VENEZUELAE'''
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===CHLORAMPHENICOL PHOSPHOTRANSFERASE FROM STREPTOMYCES VENEZUELAE===
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==Overview==
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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 &gt;9 A upon substrate binding.
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(as it appears on PubMed at http://www.pubmed.gov), where 10835366 is the PubMed ID number.
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{{ABSTRACT_PUBMED_10835366}}
==About this Structure==
==About this Structure==
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[[Category: Mononucleotide binding fold]]
[[Category: Mononucleotide binding fold]]
[[Category: Phosphorylation]]
[[Category: Phosphorylation]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 06:17:01 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 00:04:50 2008''

Revision as of 21:04, 28 July 2008

Image:1qhn.png

Template:STRUCTURE 1qhn

CHLORAMPHENICOL PHOSPHOTRANSFERASE FROM STREPTOMYCES VENEZUELAE

Template:ABSTRACT PUBMED 10835366

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 Tue Jul 29 00:04:50 2008

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