1u5b is a 2 chain structure with sequence from Human. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
[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] [ODBB_HUMAN] Defects in BCKDHB are the cause of maple syrup urine disease type IB (MSUD1B) [MIM:248600]. MSUD is an autosomal recessive disorder characterized by mental and physical retardation, feeding problems, and a maple syrup odor to the urine.[9][10][11]
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). [ODBB_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 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.
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[12]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
↑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:https://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:https://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:https://dx.doi.org/10.1172/JCI117804
↑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
↑Edelmann L, Wasserstein MP, Kornreich R, Sansaricq C, Snyderman SE, Diaz GA. Maple syrup urine disease: identification and carrier-frequency determination of a novel founder mutation in the Ashkenazi Jewish population. Am J Hum Genet. 2001 Oct;69(4):863-8. Epub 2001 Aug 16. PMID:11509994 doi:S0002-9297(07)61141-0
↑Wang YP, Qi ML, Li TT, Zhao YJ. Two novel mutations in the BCKDHB gene (R170H, Q346R) cause the classic form of maple syrup urine disease (MSUD). Gene. 2012 Apr 25;498(1):112-5. doi: 10.1016/j.gene.2012.01.082. Epub 2012 Feb 3. PMID:22326532 doi:10.1016/j.gene.2012.01.082
↑Wynn RM, Kato M, Machius M, Chuang JL, Li J, Tomchick DR, Chuang DT. Molecular mechanism for regulation of the human mitochondrial branched-chain alpha-ketoacid dehydrogenase complex by phosphorylation. Structure. 2004 Dec;12(12):2185-96. PMID:15576032 doi:10.1016/j.str.2004.09.013
