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From toxic aggregates to properly folded proteins - Functional characterization of a novel HSP104 ortholog in mammals, and insight into the molecular architecture and substrate specificities of Type I and Type II HSP40S

Grant number: 11/07320-5
Support type:Scholarships in Brazil - Post-Doctorate
Effective date (Start): September 01, 2011
Effective date (End): August 31, 2013
Field of knowledge:Biological Sciences - Biochemistry - Enzymology
Principal researcher:Carlos Henrique Inacio Ramos
Grantee:David Zachary Mokry
Home Institution: Instituto de Química (IQ). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

The proper structure of proteins is maintained by a sophisticated system of proteinchaperones. When this system is disrupted, proteins can become unfolded, lose function,and form toxic aggregates that are implicated in a number of different pathologies. Theseaggregates can be eliminated by specialized chaperones that contain a disaggregaseactivity working in conjunction with an Hsp70 system that is itself regulated by differentHsp40 co-chaperones. To date, no disaggregase has been described in humans.Furthermore, precisely how different Hsp40s regulate Hsp70 activity is not fullyunderstood, although the orientation of a conserved J-domain within the structure isknown to be important. In this project, we propose to demonstrate for the first time adisaggregase activity for a human protein, SKD3, and determine what effects silencing itsexpression has on cells during high stress conditions. Furthermore, we will obtain highresolutionstructural information on wild-type and mutant type I and type II hsp40 cochaperonesfrom yeast by NMR TROSY, providing the first high resolution study on howthe central domain dictates the quaternary structure of the J domain. Furthermore, we alsowill identify novel substrates of human type I and type II Hsp40s, and provide insightinto the substrate specificities of each. The information obtained in these studies willsignificantly broaden our understanding of how chaperone systems cooperate to converttoxic protein aggregates into functional proteins, with specific emphasis on human andother mammalian chaperone systems.