2ad5
From Proteopedia
(New page: 200px<br /><applet load="2ad5" size="450" color="white" frame="true" align="right" spinBox="true" caption="2ad5, resolution 2.8Å" /> '''Mechanisms of feedbac...) |
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| - | [[Image:2ad5.jpg|left|200px]]<br /><applet load="2ad5" size=" | + | [[Image:2ad5.jpg|left|200px]]<br /><applet load="2ad5" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="2ad5, resolution 2.8Å" /> | caption="2ad5, resolution 2.8Å" /> | ||
'''Mechanisms of feedback regulation and drug resistance of CTP synthetases: structure of the E. coli CTPS/CTP complex at 2.8-Angstrom resolution.'''<br /> | '''Mechanisms of feedback regulation and drug resistance of CTP synthetases: structure of the E. coli CTPS/CTP complex at 2.8-Angstrom resolution.'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Cytidine triphosphate synthetases (CTPSs) synthesize CTP and regulate its | + | Cytidine triphosphate synthetases (CTPSs) synthesize CTP and regulate its intracellular concentration through direct interactions with the four ribonucleotide triphosphates. In particular, CTP product is a feedback inhibitor that competes with UTP substrate. Selected CTPS mutations that impart resistance to pyrimidine antimetabolite inhibitors also relieve CTP inhibition and cause a dramatic increase in intracellular CTP concentration, indicating that the drugs act by binding to the CTP inhibitory site. Resistance mutations map to a pocket that, although adjacent, does not coincide with the expected UTP binding site in apo Escherichia coli CTPS [EcCTPS; Endrizzi, J. A., et al. (2004) Biochemistry 43, 6447-6463], suggesting allosteric rather than competitive inhibition. Here, bound CTP and ADP were visualized in catalytically active EcCTPS crystals soaked in either ATP and UTP substrates or ADP and CTP products. The CTP cytosine ring resides in the pocket predicted by the resistance mutations, while the triphosphate moiety overlaps the putative UTP triphosphate binding site, explaining how CTP competes with UTP while CTP resistance mutations are acquired without loss of catalytic efficiency. Extensive complementarity and interaction networks at the interfacial binding sites provide the high specificity for pyrimidine triphosphates and mediate nucleotide-dependent tetramer formation. Overall, these results depict a novel product inhibition strategy in which shared substrate and product moieties bind to a single subsite while specificity is conferred by separate subsites. This arrangement allows for independent adaptation of UTP and CTP binding affinities while efficiently utilizing the enzyme surface. |
==About this Structure== | ==About this Structure== | ||
| - | 2AD5 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with MG, ADP and CTP as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/CTP_synthase CTP synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=6.3.4.2 6.3.4.2] Full crystallographic information is available from [http:// | + | 2AD5 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with <scene name='pdbligand=MG:'>MG</scene>, <scene name='pdbligand=ADP:'>ADP</scene> and <scene name='pdbligand=CTP:'>CTP</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/CTP_synthase CTP synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=6.3.4.2 6.3.4.2] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2AD5 OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Escherichia coli]] | [[Category: Escherichia coli]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Anderson, P | + | [[Category: Anderson, P M.]] |
| - | [[Category: Baldwin, E | + | [[Category: Baldwin, E P.]] |
| - | [[Category: Endrizzi, J | + | [[Category: Endrizzi, J A.]] |
[[Category: Kim, H.]] | [[Category: Kim, H.]] | ||
[[Category: ADP]] | [[Category: ADP]] | ||
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[[Category: rossman fold]] | [[Category: rossman fold]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 16:26:17 2008'' |
Revision as of 14:26, 21 February 2008
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Mechanisms of feedback regulation and drug resistance of CTP synthetases: structure of the E. coli CTPS/CTP complex at 2.8-Angstrom resolution.
Overview
Cytidine triphosphate synthetases (CTPSs) synthesize CTP and regulate its intracellular concentration through direct interactions with the four ribonucleotide triphosphates. In particular, CTP product is a feedback inhibitor that competes with UTP substrate. Selected CTPS mutations that impart resistance to pyrimidine antimetabolite inhibitors also relieve CTP inhibition and cause a dramatic increase in intracellular CTP concentration, indicating that the drugs act by binding to the CTP inhibitory site. Resistance mutations map to a pocket that, although adjacent, does not coincide with the expected UTP binding site in apo Escherichia coli CTPS [EcCTPS; Endrizzi, J. A., et al. (2004) Biochemistry 43, 6447-6463], suggesting allosteric rather than competitive inhibition. Here, bound CTP and ADP were visualized in catalytically active EcCTPS crystals soaked in either ATP and UTP substrates or ADP and CTP products. The CTP cytosine ring resides in the pocket predicted by the resistance mutations, while the triphosphate moiety overlaps the putative UTP triphosphate binding site, explaining how CTP competes with UTP while CTP resistance mutations are acquired without loss of catalytic efficiency. Extensive complementarity and interaction networks at the interfacial binding sites provide the high specificity for pyrimidine triphosphates and mediate nucleotide-dependent tetramer formation. Overall, these results depict a novel product inhibition strategy in which shared substrate and product moieties bind to a single subsite while specificity is conferred by separate subsites. This arrangement allows for independent adaptation of UTP and CTP binding affinities while efficiently utilizing the enzyme surface.
About this Structure
2AD5 is a Single protein structure of sequence from Escherichia coli with , and as ligands. Active as CTP synthase, with EC number 6.3.4.2 Full crystallographic information is available from OCA.
Reference
Mechanisms of product feedback regulation and drug resistance in cytidine triphosphate synthetases from the structure of a CTP-inhibited complex., Endrizzi JA, Kim H, Anderson PM, Baldwin EP, Biochemistry. 2005 Oct 18;44(41):13491-9. PMID:16216072
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