Physics and biology team up to tackle protein folding debate

A series of discussions in a campus café in Lausanne has blossomed into an extraordinary collaboration between EPFL physics professor Paolo De Los Rios and University of Lausanne biology professor Pierre Goloubinoff. Using the principles of statistical physics, they have identified a simple, single mechanism that explains the mechanical role of molecular chaperones in protein folding and translocation, settling at the same time a long-standing controversy over this process.



Molecular chaperones are specialized proteins that help other proteins find their proper conformations and reach their proper places in the cell. For more than two decades, biologists and biochemists have debated how one of these chaperones, Hsp70, manages the mechanical job of unfolding protein aggregates and pulling proteins into the various compartments of the cell. Is it by a "Power Stroke", in which the chaperone would use leverage and produce a mechanical force that pulls the protein, or a "Brownian Ratchet", in which the presence of the chaperone and the thermal fluctuations of the protein itself combine to pull the protein? There is no overwhelming evidence in favor of one explanation over the other. More importantly, neither theory explains the full range of Hsp70's activity.

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