2qta
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(New page: 200px<br /><applet load="2qta" size="450" color="white" frame="true" align="right" spinBox="true" caption="2qta, resolution 1.850Å" /> '''E. coli Pyruvate de...)
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Revision as of 11:47, 21 November 2007
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E. coli Pyruvate dehydrogenase E1 component E401K mutant with thiamin diphosphate
Overview
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 E. coli pyruvate dehydrogenase complex, (E1ec) become organized only on binding a substrate analog which is, capable of forming a stable thiamin diphosphate-bound covalent, intermediate. We showed that residue H407 on the inner loop has a key role, in the mechanism, especially in the reductive acetylation of the E2ec, component, while 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 H407, 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 E1ec and E2ec components.
About this Structure
2QTA is a Single protein structure of sequence from Escherichia coli with MG and TDP as ligands. Active as Pyruvate dehydrogenase (acetyl-transferring), with EC number 1.2.4.1 Full crystallographic information is available from OCA.
Reference
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 Jul 17;. PMID:17635929
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