1qhy: Difference between revisions

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[[Image:1qhy.jpg|left|200px]]<br /><applet load="1qhy" size="~~450~~" color="white" frame="true" align="right" spinBox="true"

[[Image:1qhy.jpg|left|200px]]<br /><applet load="1qhy" size="350" color="white" frame="true" align="right" spinBox="true"

caption="1qhy, resolution 2.60Å" />

'''CHLORAMPHENICOL PHOSPHOTRANSFERASE FROM STREPTOMYCES VENEZUELAE IN COMPLEX WITH ATPGAMMAS AND CHLORAMPHENICOL'''<br />

==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.

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==

1QHY 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, MG, AGS and CLM as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://~~ispc~~.weizmann.ac.il/oca-bin/ocashort?id=1QHY OCA].

1QHY 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>, <scene name='pdbligand=MG:'>MG</scene>, <scene name='pdbligand=AGS:'>AGS</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=1QHY OCA].

==Reference==

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[[Category: transferase]]

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@@ Line 1: / Line 1: @@
-[[Image:1qhy.jpg|left|200px]]<br /><applet load="1qhy" size="450" color="white" frame="true" align="right" spinBox="true"
+[[Image:1qhy.jpg|left|200px]]<br /><applet load="1qhy" size="350" color="white" frame="true" align="right" spinBox="true"
 caption="1qhy, resolution 2.60&Aring;" />
 '''CHLORAMPHENICOL PHOSPHOTRANSFERASE FROM STREPTOMYCES VENEZUELAE IN COMPLEX WITH ATPGAMMAS AND CHLORAMPHENICOL'''<br />
 ==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 &gt;9 A upon, substrate binding.
+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.
 ==About this Structure==
-QHY 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, MG, AGS and CLM as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1QHY OCA].
+QHY 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>, <scene name='pdbligand=MG:'>MG</scene>, <scene name='pdbligand=AGS:'>AGS</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=1QHY OCA].
 ==Reference==
@@ Line 24: / Line 24: @@
 [[Category: transferase]]
-''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Wed Nov 21 00:43:23 2007''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:39:46 2008''