Intracellular protein degradation plays a number of critically important roles in the normal physiology and in the pathology of cellular protein metabolism. This highly regulated process is a key determinant of the quality and quantity of cellular protein; it serves to selectively remove metabolically or genetically damaged proteins from the cell, and controls levels of individual cellular proteins (including those with important regulatory functions), as well as the net growth or atrophy of tissues. Despite the importance of intracellular protein degradation, the biochemical mechanisms by which it occurs are poorly defined. The long term objectives of this research program are to provide a comprehensive understanding of both the biochemical mechanisms of intracellular protein degradation and the physiological regulation of this process in intact cells and tissues. The specific goal of the proposed research is to determine the biochemical mechanisms of regulation of the multicatalytic protease, the proteasome, by two newly discovered activator proteins, termed PA28 and PA700. Each proteasome activator has been purified and paretically characterized. PA28 and PA700 each activates the proteasomes's three distinct peptidase activities, and together they activate the proteasome's action of PA700, requires hydrolysis of ATP. The first portion of this work will define the biochemical mechanisms regulatory processes involved in each of these actions. The second portion of the work will determine whether the proteasome, PA700, and/or PA28 are components of a large """"""""26S protease"""""""" known to degrade ubiquitinated proteins. The third portion of the work will determine the primary structures of PA28 and PA700 by recombinant DNA methodologies. This essential information will be used for the final portion of the work, which will establish detailed structure/function relationships for PA28. This analysis will use synthetic peptide corresponding to functional domains of PA28, as well as native and mutant PA28 proteins expressed in E. coli. These studies will provide important information about the biochemical function and regulation of the proteasome, and will serve as the basis for exploration of its role in physiological and pathological states of intracellular protein degradation.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
1R01DK046181-01A2
Application #
2145367
Study Section
Physiological Chemistry Study Section (PC)
Project Start
1994-07-01
Project End
1998-06-30
Budget Start
1994-07-01
Budget End
1995-06-30
Support Year
1
Fiscal Year
1994
Total Cost
Indirect Cost
Name
University of Texas Sw Medical Center Dallas
Department
Physiology
Type
Schools of Medicine
DUNS #
City
Dallas
State
TX
Country
United States
Zip Code
75390
Li, Xiaohua; Thompson, David; Kumar, Brajesh et al. (2014) Molecular and cellular roles of PI31 (PSMF1) protein in regulation of proteasome function. J Biol Chem 289:17392-405
Demartino, George N (2012) Reconstitution of PA700, the 19S regulatory particle, from purified precursor complexes. Methods Mol Biol 832:443-52
Kim, Young-Chan; DeMartino, George N (2011) C termini of proteasomal ATPases play nonequivalent roles in cellular assembly of mammalian 26 S proteasome. J Biol Chem 286:26652-66
Agarwal, Anil K; Xing, Chao; DeMartino, George N et al. (2010) PSMB8 encoding the ýý5i proteasome subunit is mutated in joint contractures, muscle atrophy, microcytic anemia, and panniculitis-induced lipodystrophy syndrome. Am J Hum Genet 87:866-72
Kumar, Brajesh; Kim, Young-Chan; DeMartino, George N (2010) The C terminus of Rpt3, an ATPase subunit of PA700 (19 S) regulatory complex, is essential for 26 S proteasome assembly but not for activation. J Biol Chem 285:39523-35
Lewis, Karen A; Yaeger, Arynn; DeMartino, George N et al. (2010) Accelerated formation of alpha-synuclein oligomers by concerted action of the 20S proteasome and familial Parkinson mutations. J Bioenerg Biomembr 42:85-95
Li, Xiaohua; Demartino, George N (2009) Variably modulated gating of the 26S proteasome by ATP and polyubiquitin. Biochem J 421:397-404
Djakovic, Stevan N; Schwarz, Lindsay A; Barylko, Barbara et al. (2009) Regulation of the proteasome by neuronal activity and calcium/calmodulin-dependent protein kinase II. J Biol Chem 284:26655-65
DeMartino, George N (2009) PUPylation: something old, something new, something borrowed, something Glu. Trends Biochem Sci 34:155-8
Thompson, David; Hakala, Kevin; DeMartino, George N (2009) Subcomplexes of PA700, the 19 S regulator of the 26 S proteasome, reveal relative roles of AAA subunits in 26 S proteasome assembly and activation and ATPase activity. J Biol Chem 284:24891-903

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