| Structural highlights
1v1r is a 2 chain structure with sequence from Homo sapiens. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
| | Method: | X-ray diffraction, Resolution 1.8Å |
| Ligands: | , , , , |
| Resources: | FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT |
Disease
ODBA_HUMAN Defects in BCKDHA are a cause of maple syrup urine disease type IA (MSUD1A) [MIM:248600. MSUD is an autosomal recessive disorder characterized by mental and physical retardation, feeding problems, and a maple syrup odor to the urine.[1] [2] [3] [4] [5] [6] [7] [8]
Function
ODBA_HUMAN The branched-chain alpha-keto dehydrogenase complex catalyzes the overall conversion of alpha-keto acids to acyl-CoA and CO(2). It contains multiple copies of three enzymatic components: branched-chain alpha-keto acid decarboxylase (E1), lipoamide acyltransferase (E2) and lipoamide dehydrogenase (E3).
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
The decarboxylase/dehydrogenase (E1b) component of the 4-megadalton human branched-chain alpha-keto acid dehydrogenase (BCKD) metabolic machine is a thiamin diphosphate (ThDP)-dependent enzyme with a heterotetrameric cofactor-binding fold. The E1b component catalyzes the decarboxylation of alpha-keto acids and the subsequent reductive acylation of the lipoic acid-bearing domain (LBD) from the 24-meric transacylase (E2b) core. In the present study, we show that the binding of cofactor ThDP to the E1b active site induces a disorder-to-order transition of the conserved phosphorylation loop carrying the two phosphorylation sites Ser(292)-alpha and Ser(302)-alpha, as deduced from the 1.80-1.85 A apoE1b and holoE1b structures. The induced loop conformation is essential for the recognition of lipoylated LBD to initiate E1b-catalyzed reductive acylation. Alterations of invariant Arg(287)-alpha, Asp(295)-alpha, Tyr(300)-alpha, and Arg(301)-alpha that form a hydrogen-bonding network in the phosphorylation loop result in the disordering of the loop conformation as elucidated by limited proteolysis, accompanied by the impaired binding and diminished reductive acylation of lipoylated LBD. In contrast, k(cat) values for E1b-catalyzed decarboxylation of the alpha-keto acid are higher in these E1b mutants than in wild-type E1b, with higher K(m) values for the substrate in the mutants. ThDP binding that orders the loop prevents phosphorylation of E1b by the BCKD kinase and averts the inactivation of wild-type E1b, but not the above mutants, by this covalent modification. Our results establish that the cross-talk between the bound ThDP and the phosphorylation loop conformation serves as a feed-forward switch for multiple reaction steps in the BCKD metabolic machine.
Cross-talk between thiamin diphosphate binding and phosphorylation loop conformation in human branched-chain alpha-keto acid decarboxylase/dehydrogenase.,Li J, Wynn RM, Machius M, Chuang JL, Karthikeyan S, Tomchick DR, Chuang DT J Biol Chem. 2004 Jul 30;279(31):32968-78. Epub 2004 May 27. PMID:15166214[9]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Dariush N, Fisher CW, Cox RP, Chuang DT. Structure of the gene encoding the entire mature E1 alpha subunit of human branched-chain alpha-keto acid dehydrogenase complex. FEBS Lett. 1991 Jun 17;284(1):34-8. PMID:2060625
- ↑ Chuang JL, Fisher CR, Cox RP, Chuang DT. Molecular basis of maple syrup urine disease: novel mutations at the E1 alpha locus that impair E1(alpha 2 beta 2) assembly or decrease steady-state E1 alpha mRNA levels of branched-chain alpha-keto acid dehydrogenase complex. Am J Hum Genet. 1994 Aug;55(2):297-304. PMID:8037208
- ↑ Zhang B, Edenberg HJ, Crabb DW, Harris RA. Evidence for both a regulatory mutation and a structural mutation in a family with maple syrup urine disease. J Clin Invest. 1989 Apr;83(4):1425-9. PMID:2703538 doi:http://dx.doi.org/10.1172/JCI114033
- ↑ Matsuda I, Nobukuni Y, Mitsubuchi H, Indo Y, Endo F, Asaka J, Harada A. A T-to-A substitution in the E1 alpha subunit gene of the branched-chain alpha-ketoacid dehydrogenase complex in two cell lines derived from Menonite maple syrup urine disease patients. Biochem Biophys Res Commun. 1990 Oct 30;172(2):646-51. PMID:2241958
- ↑ Fisher CR, Fisher CW, Chuang DT, Cox RP. Occurrence of a Tyr393----Asn (Y393N) mutation in the E1 alpha gene of the branched-chain alpha-keto acid dehydrogenase complex in maple syrup urine disease patients from a Mennonite population. Am J Hum Genet. 1991 Aug;49(2):429-34. PMID:1867199
- ↑ Fisher CR, Chuang JL, Cox RP, Fisher CW, Star RA, Chuang DT. Maple syrup urine disease in Mennonites. Evidence that the Y393N mutation in E1 alpha impedes assembly of the E1 component of branched-chain alpha-keto acid dehydrogenase complex. J Clin Invest. 1991 Sep;88(3):1034-7. PMID:1885764 doi:http://dx.doi.org/10.1172/JCI115363
- ↑ Nobukuni Y, Mitsubuchi H, Hayashida Y, Ohta K, Indo Y, Ichiba Y, Endo F, Matsuda I. Heterogeneity of mutations in maple syrup urine disease (MSUD): screening and identification of affected E1 alpha and E1 beta subunits of the branched-chain alpha-keto-acid dehydrogenase multienzyme complex. Biochim Biophys Acta. 1993 Nov 25;1225(1):64-70. PMID:8161368
- ↑ Chuang JL, Davie JR, Chinsky JM, Wynn RM, Cox RP, Chuang DT. Molecular and biochemical basis of intermediate maple syrup urine disease. Occurrence of homozygous G245R and F364C mutations at the E1 alpha locus of Hispanic-Mexican patients. J Clin Invest. 1995 Mar;95(3):954-63. PMID:7883996 doi:http://dx.doi.org/10.1172/JCI117804
- ↑ Li J, Wynn RM, Machius M, Chuang JL, Karthikeyan S, Tomchick DR, Chuang DT. Cross-talk between thiamin diphosphate binding and phosphorylation loop conformation in human branched-chain alpha-keto acid decarboxylase/dehydrogenase. J Biol Chem. 2004 Jul 30;279(31):32968-78. Epub 2004 May 27. PMID:15166214 doi:http://dx.doi.org/10.1074/jbc.M403611200
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