How proteins fold, that is attain their three-dimensional structure, is a fundamental biological process with important implications for human health. Misfolded proteins are often toxic, as illustrated by the number of neurodegenerative diseases referred to as """"""""protein folding diseases"""""""". Molecular chaperones play vital roles in remodeling protein structure -- assisting de novo protein folding, preventing protein aggregation and disassembling protein complexes. Hsp70-based machineries, having J-proteins as obligate components, are amongst the most highly conserved molecular chaperone systems. J-proteins are a very diverse set of proteins, having only the 70 amino acid J-domain in common. All J-proteins share the ability to stimulate the ATPase activity of their partner Hsp70s, allowing them to capture client proteins. But it is their functional diversity that enables them to orchestrate Hsp70?s capacity to participate in a wide array of complex and diverse biological functions. This proposal focuses on understanding the basis of the specificity of J-proteins function. Two J-proteins of the yeast cytosol have been chosen for in depth analysis: Sis1 and Zuo1. This choice is based on their critical importance and their high degree of sequence conservation. Their human homologs are able to substitute for the yeast proteins, thus the outcome of this work will serve as a paradigm for understanding J-protein function in other organisms. To understand the specificity of Sis1, its function in the propagation of yeast prions will be exploited, as it is specifically required for fragmentation of prion complexes. Thus, results will also yield important information about the biogenesis and propagation of these self-replicating amyloid protein aggregates. Zuo1 is a highly conserved ribosome-associated chaperone that facilitates interaction of Hsp70 with nascent polypeptides as they exit the ribosome. Ribosome-associated chaperones serve as a link between protein synthesis and protein folding and are thus a key to the cell?s production of functional proteins. In addition, we will investigate roles of molecular chaperones in the nucleus, focusing on novel regulatory functions independent of and separable from chaperone activity.

Public Health Relevance

The research described in this proposal focuses on understanding the processes of protein folding and maturation within living cells and the important roles of molecular chaperones in them. Productive protein folding is critical to normal cell function;protein misfolding is the primary cause of many human diseases, including cystic fibrosis and neurodegenerative diseases such as Alzheimer's disease.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM031107-31
Application #
8292197
Study Section
Membrane Biology and Protein Processing (MBPP)
Program Officer
Maas, Stefan
Project Start
1982-07-01
Project End
2014-06-30
Budget Start
2012-07-01
Budget End
2014-06-30
Support Year
31
Fiscal Year
2012
Total Cost
$456,993
Indirect Cost
$147,396
Name
University of Wisconsin Madison
Department
Biochemistry
Type
Schools of Earth Sciences/Natur
DUNS #
161202122
City
Madison
State
WI
Country
United States
Zip Code
53715
Schilke, Brenda A; Ciesielski, Szymon J; Ziegelhoffer, Thomas et al. (2017) Broadening the functionality of a J-protein/Hsp70 molecular chaperone system. PLoS Genet 13:e1007084
Lee, Kanghyun; Sharma, Ruchika; Shrestha, Om Kumar et al. (2016) Dual interaction of the Hsp70 J-protein cochaperone Zuotin with the 40S and 60S ribosomal subunits. Nat Struct Mol Biol 23:1003-1010
Yonashiro, Ryo; Tahara, Erich B; Bengtson, Mario H et al. (2016) The Rqc2/Tae2 subunit of the ribosome-associated quality control (RQC) complex marks ribosome-stalled nascent polypeptide chains for aggregation. Elife 5:e11794
Kaschner, Lindsey A; Sharma, Ruchika; Shrestha, Om Kumar et al. (2015) A conserved domain important for association of eukaryotic J-protein co-chaperones Jjj1 and Zuo1 with the ribosome. Biochim Biophys Acta 1853:1035-45
Yu, Hyun Young; Ziegelhoffer, Thomas; Craig, Elizabeth A (2015) Functionality of Class A and Class B J-protein co-chaperones with Hsp70. FEBS Lett 589:2825-30
Yu, Hyun Young; Ziegelhoffer, Thomas; Osipiuk, Jerzy et al. (2015) Roles of intramolecular and intermolecular interactions in functional regulation of the Hsp70 J-protein co-chaperone Sis1. J Mol Biol 427:1632-43
Ciesielski, Grzegorz L; Plotka, Magdalena; Manicki, Mateusz et al. (2013) Nucleoid localization of Hsp40 Mdj1 is important for its function in maintenance of mitochondrial DNA. Biochim Biophys Acta 1833:2233-43
Sahi, Chandan; Kominek, Jacek; Ziegelhoffer, Thomas et al. (2013) Sequential duplications of an ancient member of the DnaJ-family expanded the functional chaperone network in the eukaryotic cytosol. Mol Biol Evol 30:985-98
Kominek, Jacek; Marszalek, Jaroslaw; Neuvéglise, Cécile et al. (2013) The complex evolutionary dynamics of Hsp70s: a genomic and functional perspective. Genome Biol Evol 5:2460-77
Ducett, Jeanette K; Peterson, Francis C; Hoover, Lindsey A et al. (2013) Unfolding of the C-terminal domain of the J-protein Zuo1 releases autoinhibition and activates Pdr1-dependent transcription. J Mol Biol 425:19-31

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