2a68
From Proteopedia
(New page: 200px<br /><applet load="2a68" size="450" color="white" frame="true" align="right" spinBox="true" caption="2a68, resolution 2.50Å" /> '''Crystal structure of...) |
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| - | [[Image:2a68.gif|left|200px]]<br /><applet load="2a68" size=" | + | [[Image:2a68.gif|left|200px]]<br /><applet load="2a68" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="2a68, resolution 2.50Å" /> | caption="2a68, resolution 2.50Å" /> | ||
'''Crystal structure of the T. thermophilus RNA polymerase holoenzyme in complex with antibiotic rifabutin'''<br /> | '''Crystal structure of the T. thermophilus RNA polymerase holoenzyme in complex with antibiotic rifabutin'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Rifamycins, the clinically important antibiotics, target bacterial RNA | + | Rifamycins, the clinically important antibiotics, target bacterial RNA polymerase (RNAP). A proposed mechanism in which rifamycins sterically block the extension of nascent RNA beyond three nucleotides does not alone explain why certain RNAP mutations confer resistance to some but not other rifamycins. Here we show that unlike rifampicin and rifapentin, and contradictory to the steric model, rifabutin inhibits formation of the first and second phosphodiester bonds. We report 2.5 A resolution structures of rifabutin and rifapentin complexed with the Thermus thermophilus RNAP holoenzyme. The structures reveal functionally important distinct interactions of antibiotics with the initiation sigma factor. Strikingly, both complexes lack the catalytic Mg2+ ion observed in the apo-holoenzyme, whereas an increase in Mg2+ concentration confers resistance to rifamycins. We propose that a rifamycin-induced signal is transmitted over approximately 19 A to the RNAP active site to slow down catalysis. Based on structural predictions, we designed enzyme substitutions that apparently interrupt this allosteric signal. |
==About this Structure== | ==About this Structure== | ||
| - | 2A68 is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Thermus_thermophilus Thermus thermophilus] with RBT, ZN and MG as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/DNA-directed_RNA_polymerase DNA-directed RNA polymerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.7.7.6 2.7.7.6] Full crystallographic information is available from [http:// | + | 2A68 is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Thermus_thermophilus Thermus thermophilus] with <scene name='pdbligand=RBT:'>RBT</scene>, <scene name='pdbligand=ZN:'>ZN</scene> and <scene name='pdbligand=MG:'>MG</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/DNA-directed_RNA_polymerase DNA-directed RNA polymerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.7.7.6 2.7.7.6] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2A68 OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Matsugaki, N.]] | [[Category: Matsugaki, N.]] | ||
[[Category: Perederina, A.]] | [[Category: Perederina, A.]] | ||
| - | [[Category: RSGI, RIKEN | + | [[Category: RSGI, RIKEN Structural Genomics/Proteomics Initiative.]] |
[[Category: Svetlov, D.]] | [[Category: Svetlov, D.]] | ||
[[Category: Svetlov, V.]] | [[Category: Svetlov, V.]] | ||
| - | [[Category: Tahirov, T | + | [[Category: Tahirov, T H.]] |
| - | [[Category: Vassylyev, D | + | [[Category: Vassylyev, D G.]] |
| - | [[Category: Vassylyeva, M | + | [[Category: Vassylyeva, M N.]] |
[[Category: Wakatsuki, S.]] | [[Category: Wakatsuki, S.]] | ||
[[Category: MG]] | [[Category: MG]] | ||
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[[Category: transcription regulation]] | [[Category: transcription regulation]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 16:23:59 2008'' |
Revision as of 14:24, 21 February 2008
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Crystal structure of the T. thermophilus RNA polymerase holoenzyme in complex with antibiotic rifabutin
Overview
Rifamycins, the clinically important antibiotics, target bacterial RNA polymerase (RNAP). A proposed mechanism in which rifamycins sterically block the extension of nascent RNA beyond three nucleotides does not alone explain why certain RNAP mutations confer resistance to some but not other rifamycins. Here we show that unlike rifampicin and rifapentin, and contradictory to the steric model, rifabutin inhibits formation of the first and second phosphodiester bonds. We report 2.5 A resolution structures of rifabutin and rifapentin complexed with the Thermus thermophilus RNAP holoenzyme. The structures reveal functionally important distinct interactions of antibiotics with the initiation sigma factor. Strikingly, both complexes lack the catalytic Mg2+ ion observed in the apo-holoenzyme, whereas an increase in Mg2+ concentration confers resistance to rifamycins. We propose that a rifamycin-induced signal is transmitted over approximately 19 A to the RNAP active site to slow down catalysis. Based on structural predictions, we designed enzyme substitutions that apparently interrupt this allosteric signal.
About this Structure
2A68 is a Protein complex structure of sequences from Thermus thermophilus with , and as ligands. Active as DNA-directed RNA polymerase, with EC number 2.7.7.6 Full crystallographic information is available from OCA.
Reference
Allosteric modulation of the RNA polymerase catalytic reaction is an essential component of transcription control by rifamycins., Artsimovitch I, Vassylyeva MN, Svetlov D, Svetlov V, Perederina A, Igarashi N, Matsugaki N, Wakatsuki S, Tahirov TH, Vassylyev DG, Cell. 2005 Aug 12;122(3):351-63. PMID:16096056
Page seeded by OCA on Thu Feb 21 16:23:59 2008
Categories: DNA-directed RNA polymerase | Protein complex | Thermus thermophilus | Artsimovitch, I. | Igarashi, N. | Matsugaki, N. | Perederina, A. | RSGI, RIKEN Structural Genomics/Proteomics Initiative. | Svetlov, D. | Svetlov, V. | Tahirov, T H. | Vassylyev, D G. | Vassylyeva, M N. | Wakatsuki, S. | MG | RBT | ZN | Antibiotic | Rifabutin | Riken structural genomics/proteomics initiative | Rna polymerase holoenzyme | Rsgi | Structural genomics | Transcription regulation
