Is Hsp70 a folder or a helper protein?

Abstract

Abstract

Abstract

Proteins are important macromolecules for cellular activity; intact and correctly folded proteins are required for normal cellular functions. Therefore, a cell has a unique machinery, using heat shock proteins (Hsp), to fold other proteins in their correct three dimensional forms. Several stress factors may cause partial or total destruction of native protein structures. This destruction can be reversible for some of the proteins. Heat shock proteins help some of the unfolded proteins to refold their native states and direct irreversibly denatured proteins to lysosomes for degradation. Hsp70 is at the center of this unique mechanism. Hsp70s also harbor other biochemical functions such as ATPase activity. This article discussed some of the functions of yeast Hsp70.

Keywords: Heat shock proteins, cellular function

Özet

Hsp70 katlayıcı mı yoksa modulatör protein mi?

Proteinler hücresel aktivite için önemli makromoleküllerdir, normal hücresel fonksiyonlar için bozulmamış ve doğru katlanmış proteinler gerekir. Dolayısı ile bir hücre proteinlerini doğru üç boyutlu halde tutabilmek için, ısı şok proteinlerini kullanan oldukça özgün bir mekanizmaya sahiptir. Birçok stres faktörü protein yapılarını kısmen veya tamamen bozabilir. Bu bozuklukların bazıları giderilebilirken bazılarını onarmak mümkün olmaz. Isı şok proteinleri bir yandan katlanmamış proteinlerin doğal yapılarını kazanmalarına yardım ederken bir yandan da denatüre proteinleri parçalanmaları için lizozoma yönlendirir. Hsp70'ler aynı zamanda ATPaz gibi aktivitelere de sahiptirler. Bu yazıda maya Hsp70'in bazı fonksiyonları tartışıldı.

Anahtar sözcükler: Isı şok proteinleri, hücresel işlev

Keywords

• -

References

1. Sharma D, Martineau CN, Le Dall MT, Reidy M, Masison DC, Kabani M. Function of SSA subfamily of Hsp70 within and across species varies widely in complementing Saccharomyces cerevisiae cell growth and prion propagation. PLoS One. 2009 Aug 14;4(8):e6644.
2. Song Y, Wu YX, Jung G, Tutar Y, Eisenberg E, Greene LE, Masison DC. Role for Hsp70 chaperone in Saccharomyces cerevisiae prion seed replication. Eukaryot Cell. 2005 Feb;4(2):289-97.
3. Tutar L, Tutar Y. Heat Shock Proteins; An Overview. Curr Pharm Biotechnol. 2010 Feb 16.
4. Bukau B., Deuerling E., Pfund C. and Craig E. A. Getting newly synthesized proteins into shape. Cell. 2000 101:119–122
5. Bukau B, Weissman J, Horwich A. Molecular chaperones and protein quality control. Cell 2006;125 (3):443–451.
6. Hartl F. U. and Hayer-Hartl M. Molecular chaperones in the cytosol: from nascent chain to folded protein. Science. 2002 295: 1852–1858.
7. Goloubinoff P., Mogk A., Peres Ben Zvi A., Tomoyasu T. and Bukau B. Sequential mechanism of solubilization and refolding of stable protein aggregates by a bichaperone network. Proc. Natl. Acad. Sci. USA 1999 96: 13732–13737
8. Mayer MP, Bukau B. Hsp70 chaperones: cellular functions and molecular mechanism. Cell Mol Life Sci 2005;62(6):670–684.

9. Tutar Y, Song Y, Masison DC. Primate chaperones Hsc70 (constitutive) and Hsp70 (induced) differ functionally in supporting growth and prion propagation in Saccharomyces cerevisiae. Genetics. 2006 Feb;172(2):851-61. Epub 2005 Nov 19.
10. Tutar L, Tutar Y. Ydj1 but not Sis1 stabilizes Hsp70 protein under prolonged stress in vitro. Biopolymers. 2008 Mar;89(3):171-4.
11. Genevaux P, Georgopoulos C, Kelley WL. The Hsp70 chaperone machines of Escherichia coli: a paradigm for the repartition of chaperone functions. Mol Microbiol 2007;66(4):840–857.
12. Ben-Zvi A. P. and Goloubinoff P. Review: mechanisms of disaggregation and refolding of stable protein aggregates by molecular chaperones. J. Struct. Biol. 2001 135: 84–93
13. Ben-Zvi A., De Los Rios P., Dietler G. and Goloubinoff P. Active solubilization and refolding of stable protein aggregates by cooperative unfolding action of individual Hsp70 chaperones. J. Biol. Chem. 2004 279: 37298–37303
14. Diamant S., Peres Ben-Zvi A., Bukau B. and Goloubinoff P. Size-dependent disaggregation of stable protein aggregates by the DnaK chaperone machinery. J. Biol. Chem. 2000275: 21107–21113
15. Glover J. R. and Lindquist S. Hsp104, Hsp70 and Hsp40: a novel chaperone system that rescues previously aggregated proteins. Cell 1998 94: 73–82
16. Liberek K, Lewandowska A, Zietkiewicz S. Chaperones in control of protein disaggregation. Embo J 2008;27(2):328–335.
17. Frydman J. Folding of newly translated proteins in vivo: the role of molecular chaperones. Annu Rev Biochem 2001;70:603–647.
18. Hohfeld J, Cyr DM, Patterson C. From the cradle to the grave: molecular chaperones that may choose between folding and degradation. EMBO Rep 2001;2(10):885–890.
19. Kramer G, et al. The ribosome as a platform for co-translational processing, folding and targeting of newly synthesized proteins. Nat Struct Mol Biol 2009;16(6):589–597.
20. Young JC, Barral JM, Ulrich Hartl F. More than folding: localized functions of cytosolic chaperones. Trends Biochem Sci 2003;28(10):541–547.