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Vendredi 9 Décembre, à 10H30, en amphi Jacques Poly bâtiment 440, Pierre Goloubinoff, Professeur à la Faculté de Biologie et de Médecine de Lausanne (Suisse), donnera un séminaire sur les chaperonnes et leurs activités en tant que "foldase" et "desagregase" :

"The molecular mechanism of bacterial Hsp70 as an ATP-fuelled polypeptide unfolding enzyme"

Résumé

Stress- or mutation-induced protein misfolding and aggregation cause various age-related diseases, such as Parkinson, Alzheimer and prion diseases. The age-dependent onset of protein misfolding diseases correlates with decreased expression and activity of the chaperone network in aging cells. Molecular chaperones have long been thought to prevent the aggregation of other proteins, thereby acting as mere passive stoichiometric folding buffers that avert the formation of proteotoxic species in the cell.

Here, I shall describe the molecular mechanism by which bacterial Hsp70, assisted by its co-chaperones Hsp40 and GrpE can use the energy of ATP hydrolysis to catalytically unfold a majority of stably misfolded monomeric polypeptide substrates and convert them into natively refolded products at the cost of only 5 ATP per "rehabilitated" polypeptide. Active unfolding thus widens the spectrum of chaperone actions, from mere prevention of toxic protein conformers to their active curing in diseased cells.

A better understanding of the natural chaperone-dependent mechanisms by which young cells promote the native refolding or the recycling of toxic misfolded polypeptides, is central to slow down the early onset and treat already declared degenerative protein misfolding diseases and aging in general.

Publications récentes :

The novel hydroxylamine derivative NG-094 suppresses polyglutamine protein toxicity in Caenorhabditis elegans.
Haldimann P, Muriset M, Vígh L, Goloubinoff P.
J Biol Chem. 2011 May 27;286(21):18784-94.

Molecular chaperones and associated cellular clearance mechanisms against toxic protein conformers in Parkinson's disease.
Hinault MP, Farina-Henriquez-Cuendet A, Goloubinoff P.
Neurodegener Dis. 2011;8(6):397-412.

Probing the different chaperone activities of the bacterial HSP70-HSP40 system using a thermolabile luciferase substrate.
Sharma SK, De Los Rios P, Goloubinoff P.
Proteins. 2011 Jun;79(6):1991-8.

The kinetic parameters and energy cost of the Hsp70 chaperone as a polypeptide unfoldase.
Sharma SK, De los Rios P, Christen P, Lustig A, Goloubinoff P.
Nat Chem Biol. 2010 Dec;6(12):914-20.

Heat perception and signalling in plants: a tortuous path to thermotolerance.
Saidi Y, Finka A, Goloubinoff P.
New Phytol. 2011 May;190(3):556-65.

Membrane lipid composition affects plant heat sensing and modulates Ca(2+)-dependent heat shock response.
Saidi Y, Peter M, Finka A, Cicekli C, Vigh L, Goloubinoff P.
Plant Signal Behav. 2010 Dec;5(12):1530-3.

Stable alpha-synuclein oligomers strongly inhibit chaperone activity of the Hsp70 system by weak interactions with J-domain co-chaperones.
Hinault MP, Cuendet AF, Mattoo RU, Mensi M, Dietler G, Lashuel HA, Goloubinoff P.
J Biol Chem. 2010 Dec 3;285(49):38173-82.

Disaggregating chaperones: an unfolding story.
Sharma SK, Christen P, Goloubinoff P.
Curr Protein Pept Sci. 2009 Oct;10(5):432-46.

Pour en savoir plus, vous pouvez consulter son site web à l'adresse : 

 http://www.unil.ch/dbmv/page8007_en.html