It takes a dimer to tango

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Under changes in conditions as diverse as temperature, oxidation or pH, proteins in an organism may undergo harmful denaturation. Small Heat Shock proteins act as “paramedics of the cell”: during such events they quicky intervene by binding nascently unfolding proteins, leading them to refolding or denaturation pathways. Small heat shock proteins are ubiquitous in all kingdoms of life, but especially effective in plants: after all, plants cannot escape from harsh environmental conditions!

Collaborating with Benesch (University of Oxford) and Vierling (UMass) groups, we have contributed to shedding light into the mode of action of small Heat Shock Proteins in wheat and pea.

We describe a mechanism whereby dimers of these proteins are responsible for capturing their substrate, before assemblying into larger complexes. With our own integrative modelling methods using distance restraints and collision cross-section measurements, we  demonstrate that small heat shock protein dimers assemble into characteristic tetrahedral structures (see on the right).

These results point towards ways to design small heat shock proteins customized to function at desired temperatures.

Santhanagopalan I., Degiacomi M.T., Shepherd D.A., Hochberg G.K.A., Justin L.P. Benesch J.L.P.,  Vierling E., (2018). It takes a dimer to tango: Oligomeric small heat shock proteins dissociate to capture substrate, Journal of Biological Chemisty