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Unstructured Proteins: Extracting Function from Disorder

Date:  Thursday, November 9th, 2017

Speaker:  Ajay Gopinathan, UC Merced

Abstract:

Intrinsically unstructured or disordered proteins (IDPs), which form over a third of human proteins, challenge the structure-function paradigm in biology that relates the function of proteins to their unique 3-d structure, because they function without ever folding into a unique structure. This presents an interesting opportunity to use the tools of polymer physics to gain insight into IDP dynamics and function. I shall present an overview of IDPs and a couple of examples of our recent efforts to understand how IDPs can exploit conformational entropy for functional purposes. One particularly fascinating context for IDP function is the nuclear pore complex (NPC) which gates nanoscale pores in the nuclear envelope of cells. The NPC controls all traffic into and out of the nucleus using a barrier composed of a large number of IDPs that fill the pore. Despite numerous studies, the actual structure of the barrier and its mechanism of operation are poorly understood primarily because of the disordered nature of these proteins. Here, I will present our “bottom-up” approach using sequence analysis, coarse-grained simulations and polymer brush theory which points to a novel form of gated transport in operation within the nuclear pore complex based on polymer brush physics. Another striking example of the use of conformational entropy is in the translocation across the cell wall of certain bacterial IDPs. I will present evidence that this translocation depends only on cell geometry and protein length indicating that bacteria can exploit purely physical entropic mechanisms to perform this function.

Host: Raghu Parthasarathy

Time: 4:00-5:00pm
Location: 100 Willamette Hall
Reception from 3:40-3:55 Willamette Hall Paul Olum Atrium

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