2qta: Difference between revisions
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==Overview== | ==Overview== | ||
Our crystallographic studies have shown that two active center loops (an | Our crystallographic studies have shown that two active center loops (an inner loop formed by residues 401-413 and outer loop formed by residues 541-557) of the E1 component of the Escherichia coli pyruvate dehydrogenase complex become organized only on binding a substrate analog that is capable of forming a stable thiamin diphosphate-bound covalent intermediate. We showed that residue His-407 on the inner loop has a key role in the mechanism, especially in the reductive acetylation of the E. coli dihydrolipoamide transacetylase component, whereas crystallographic results showed a role of this residue in a disorder-order transformation of these two loops, and the ordered conformation gives rise to numerous new contacts between the inner loop and the active center. We present mapping of the conserved residues on the inner loop. Kinetic, spectroscopic, and crystallographic studies on some inner loop variants led us to conclude that charged residues flanking His-407 are important for stabilization/ordering of the inner loop thereby facilitating completion of the active site. The results further suggest that a disorder to order transition of the dynamic inner loop is essential for substrate entry to the active site, for sequestering active site chemistry from undesirable side reactions, as well as for communication between the E1 and E2 components of the E. coli pyruvate dehydrogenase multienzyme complex. | ||
==About this Structure== | ==About this Structure== | ||
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==Reference== | ==Reference== | ||
A dynamic loop at the active center of the | A dynamic loop at the active center of the Escherichia coli pyruvate dehydrogenase complex E1 component modulates substrate utilization and chemical communication with the E2 component., Kale S, Arjunan P, Furey W, Jordan F, J Biol Chem. 2007 Sep 21;282(38):28106-16. Epub 2007 Jul 17. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=17635929 17635929] | ||
[[Category: Escherichia coli]] | [[Category: Escherichia coli]] | ||
[[Category: Pyruvate dehydrogenase (acetyl-transferring)]] | [[Category: Pyruvate dehydrogenase (acetyl-transferring)]] | ||
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[[Category: x-ray diffraction]] | [[Category: x-ray diffraction]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 18:42:07 2008'' | ||
Revision as of 19:42, 21 February 2008
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E. coli Pyruvate dehydrogenase E1 component E401K mutant with thiamin diphosphate
OverviewOverview
Our crystallographic studies have shown that two active center loops (an inner loop formed by residues 401-413 and outer loop formed by residues 541-557) of the E1 component of the Escherichia coli pyruvate dehydrogenase complex become organized only on binding a substrate analog that is capable of forming a stable thiamin diphosphate-bound covalent intermediate. We showed that residue His-407 on the inner loop has a key role in the mechanism, especially in the reductive acetylation of the E. coli dihydrolipoamide transacetylase component, whereas crystallographic results showed a role of this residue in a disorder-order transformation of these two loops, and the ordered conformation gives rise to numerous new contacts between the inner loop and the active center. We present mapping of the conserved residues on the inner loop. Kinetic, spectroscopic, and crystallographic studies on some inner loop variants led us to conclude that charged residues flanking His-407 are important for stabilization/ordering of the inner loop thereby facilitating completion of the active site. The results further suggest that a disorder to order transition of the dynamic inner loop is essential for substrate entry to the active site, for sequestering active site chemistry from undesirable side reactions, as well as for communication between the E1 and E2 components of the E. coli pyruvate dehydrogenase multienzyme complex.
About this StructureAbout this Structure
2QTA is a Single protein structure of sequence from Escherichia coli with and as ligands. Active as Pyruvate dehydrogenase (acetyl-transferring), with EC number 1.2.4.1 Full crystallographic information is available from OCA.
ReferenceReference
A dynamic loop at the active center of the Escherichia coli pyruvate dehydrogenase complex E1 component modulates substrate utilization and chemical communication with the E2 component., Kale S, Arjunan P, Furey W, Jordan F, J Biol Chem. 2007 Sep 21;282(38):28106-16. Epub 2007 Jul 17. PMID:17635929
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