Abstract

A systematic analysis of the structure, function and regulation of the pyruvate, Alpha-ketoglutarate, and branched chain Alpha-keto acid dehydrogenase multienzyme complexes will be continued.
The specific aims are (1) to purify the branched chain Alpha-keto acid dehydrogenase phosphatase from bovine kidney to homogeneity, determine its subunit composition, and further characterize its regulation; (2) to purify and characterize the branched chain Alpha-keto acid dehydrogenase kinase from bovine kidney; (3) to further characterize pyruvate dehydrogenase phosphatase and pyruvate dehydrogenase kinase from bovine kidney and heart; (4) to separate the two different subunits comprising the pyruvate dehydrogenase component of the mammalian pyruvate dehydrogenase complex and determine the function of each subunit; (5) to continue structural studies on the Alpha-keto acid dehydrogenase complexes, subcomplexes and component enzymes thereof, using limited proteolysis, electron microscopy and X-ray diffraction. The mitochondrial pyruvate and branched chain Alpha-keto acid dehydrogenase complexes occupy key positions in metabolism, and their activities are under metabolic and hormonal control. Regulation of the flux of carbon through the pyruvate dehydrogenase complex plays an essential role in the control of energy metabolism. The branched chain Alpha-keto acids derived from the branched chain amino acids, valine, leucine and isoleucine, represent an important source of carbon for cellular energy generation, carbohydrate biosynthesis and ketone body production in various tissues. Elucidation of the structure and catalytic and regulatory properties of the isolated Alpha-keto acid dehydrogenase complexes and their component enzymes is a necessary prerequisite to understanding the in vivo regulation of their activities. Also, analysis of inherited and acquired disorders of pyruvate and branched chain amino acid metabolism that have been reported rests on knowledge of normal metabolism of these substances.

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM006590-28
Application #
3267909
Study Section
Biochemistry Study Section (BIO)
Project Start
1975-08-01
Project End
1990-11-30
Budget Start
1986-12-01
Budget End
1987-11-30
Support Year
28
Fiscal Year
1987
Total Cost
Indirect Cost

  Institution

Name
University of Texas Austin
Department
Type
Schools of Arts and Sciences
DUNS #
City
Austin
State
TX
Country
United States
Zip Code
78713

  Publications

Maeng, C Y; Yazdi, M A; Niu, X D et al. (1994) Expression, purification, and characterization of the dihydrolipoamide dehydrogenase-binding protein of the pyruvate dehydrogenase complex from Saccharomyces cerevisiae. Biochemistry 33:13801-7
Miran, S G; Lawson, J E; Reed, L J (1993) Characterization of PDH beta 1, the structural gene for the pyruvate dehydrogenase beta subunit from Saccharomyces cerevisiae. Proc Natl Acad Sci U S A 90:1252-6
Lawson, J E; Niu, X D; Browning, K S et al. (1993) Molecular cloning and expression of the catalytic subunit of bovine pyruvate dehydrogenase phosphatase and sequence similarity with protein phosphatase 2C. Biochemistry 32:8987-93
Lawson, J E; Niu, X D; Reed, L J (1991) Functional analysis of the domains of dihydrolipoamide acetyltransferase from Saccharomyces cerevisiae. Biochemistry 30:11249-54
Lawson, J E; Behal, R H; Reed, L J (1991) Disruption and mutagenesis of the Saccharomyces cerevisiae PDX1 gene encoding the protein X component of the pyruvate dehydrogenase complex. Biochemistry 30:2834-9
Lee, H Y; Hall, T B; Kee, S M et al. (1991) Purification and properties of branched-chain alpha-keto acid dehydrogenase kinase from bovine kidney. Biofactors 3:109-12
Reed, L J; Hackert, M L (1990) Structure-function relationships in dihydrolipoamide acyltransferases. J Biol Chem 265:8971-4
Niu, X D; Stoops, J K; Reed, L J (1990) Overexpression and mutagenesis of the catalytic domain of dihydrolipoamide acetyltransferase from Saccharomyces cerevisiae. Biochemistry 29:8614-9
Reed, L J; Browning, K S; Niu, X D et al. (1989) Biochemical and molecular genetic aspects of pyruvate dehydrogenase complex from Saccharomyces cerevisiae. Ann N Y Acad Sci 573:155-67
Hackert, M L; Xu, W X; Oliver, R M et al. (1989) Branched-chain alpha-keto acid dehydrogenase complex from bovine kidney: radial distribution of mass determined from dark-field electron micrographs. Biochemistry 28:6816-21

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