1x7y

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Revision as of 17:55, 12 November 2007

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spinqualitylabelsall models 1x7y, resolution 1.57Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal structure of the human mitochondrial branched-chain alpha-ketoacid dehydrogenase

Contents 1 Overview 2 Disease 3 About this Structure 4 Reference

Overview

The human mitochondrial branched-chain alpha-ketoacid dehydrogenase, complex (BCKDC) is a 4 MDa macromolecular machine comprising three, catalytic components (E1b, E2b, and E3), a kinase, and a phosphatase. The, BCKDC overall activity is tightly regulated by phosphorylation in response, to hormonal and dietary stimuli. We report that phosphorylation of, Ser292-alpha in the E1b active site channel results in an, order-to-disorder transition of the conserved phosphorylation loop, carrying the phosphoryl serine. The conformational change is triggered by, steric clashes of the phosphoryl group with invariant His291-alpha that, serves as an indispensable anchor for the phosphorylation loop through, bound thiamin diphosphate. Phosphorylation of Ser292-alpha does not, severely impede the E1b-dependent decarboxylation of alpha-ketoacids., However, the disordered loop conformation prevents phosphorylated E1b from, binding the E2b lipoyl-bearing domain, which effectively shuts off the, E1b-catalyzed reductive acylation reaction and therefore completely, inactivates BCKDC. This mechanism provides a paradigm for regulation of, mitochondrial alpha-ketoacid dehydrogenase complexes by phosphorylation.

Disease

Known diseases associated with this structure: Maple syrup urine disease, type Ia OMIM:[608348], Maple syrup urine disease, type Ib OMIM:[248611]

About this Structure

1X7Y is a Protein complex structure of sequences from Homo sapiens with K, MN, CL, TDP and GOL as ligands. Active as 3-methyl-2-oxobutanoate dehydrogenase (2-methylpropanoyl-transferring), with EC number 1.2.4.4 Full crystallographic information is available from OCA.

Reference

Molecular mechanism for regulation of the human mitochondrial branched-chain alpha-ketoacid dehydrogenase complex by phosphorylation., Wynn RM, Kato M, Machius M, Chuang JL, Li J, Tomchick DR, Chuang DT, Structure. 2004 Dec;12(12):2185-96. PMID:15576032

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