Molecular Biophysics I
2005
Session #8

Hsp70
and the
Hsp70 Molecular Chaperone Machine

I. Hsp70 Structure and Substrate Preferences
 
March 23, 2005
BMI 205/207
1:00 p.m. - 3:50 p.m.

In his "three strategies" paper (Science 260: 1903-1904, 1993), David Agard lists "block the exposed hydrophobic patches" as the first cellular strategy to prevent protein aggregation. As we shall see in this session, Hsp70 and it's co-chaperones are uniquely adapted to carry out this function. Different members of the highly conserved Hsp70 family are found both in prokaryotes and most cellular compartments of eukaryotes.

Because of the wealth of information available on the Hsp70 chaperone machine, and its many roles involving cellular protein conformation changes (and time constraints), our consideration of this molecular chaperone will be divided into two sessions:

•  Session 8 will focus on the structure and substrate recognition of Hsp70, and will include:

  • Some background information (contained in my PowerPoint slides);

  • An overview of Hsp70 function as provide by two of our course review papers (Refs. #1 & 2 below);

  • An additional review paper by Bukau & Horwich (Ref. #5 below) that discusses Hsp70 structure and its reaction cycle in greater detail;

  • The atomic structure of the substrate-binding domain of the E. coli Hsp70 "DnaK" (Ref. #6 below);

  • Determination of the 'binding motif' of DnaK (Ref. #7 below)

   

•  Session 9 (March 30, 2005) will focus on the role of the Hsp70 molecular chaperone machine in cellular 'chaperone networks', i.e., cooperation by different molecular chaperone families in an assembly-line (or 'hand-off') fashion.

  • Course review papers #3 & #4 below can provide background material here;

  • Additional references will be designated, depending on our progress in Session 8.

Student Assignments (Session 8)

•  All students should read the material on Hsp70 in the Bukau & Horwich paper (Ref. #5).

•  Students #1,3,5,7,& 9: The paper by Zhu et al, 1996 (Ref. #6; Note: A pdf version of the html paper from Science has been posted to the course pages on the Library's eReserves site. The original html version is available thru the Ovid database, using the Ovid selection "Journals @ Ovid full text" option)

•  Students #2,4,6,8, & 10 Ref. #7 (Rudiger et al, 1997)

Reference List

Course Review Papers

1.   Mogk,A., Mayer,M.P., and Deuerling,E. (2002). Mechanisms of protein folding: Molecular chaperones and their application in biotechnology. Chembiochem 3, 807-814.

2.   Walter,S. and Buchner,J. (2002). Molecular chaperones - Cellular machines for protein folding. Angewandte Chemie-International Edition 41, 1098-1113.

3.   Frydman,J. (2001). Folding of newly translated proteins in vivo: The role of molecular chaperones. Annu. Rev. Biochem. 70, 603-647.

4.   Young,J.C., Agashe,V.R., Siegers,K., and Hartl,F.U. (2004). Pathways of chaperone-mediated protein folding in the cytosol. Nature Reviews Molecular Cell Biology 5, 781-791.

New Papers for Session 8

5.   Bukau,B. and Horwich,A.L. (1998). The Hsp70 and Hsp60 chaperone machines. Cell 92, 351-366.

6.   Zhu,X., Zhao,X., Burkholder,W.F., Gragerov,A., Ogata,C.M., Gottesman,M.E., and Hendrickson,W.A. (1996). Structural analysis of substrate binding by the molecular chaperone DnaK. Science 272, 1606-1614.

7.   Rudiger,S., Germeroth,L., Schneider-Mergener,J., and Bukau,B. (1997). Substrate specificity of the DnaK chaperone determined by screening cellulose-bound peptide libraries. EMBO J. 16, 1501-1507.