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SUMMARY:Protein Disorder in Assembly and Regulation of Macromolecular Mach
 ines - Elisar Barbar\, Oregon State University
DTSTART:20141008T133000Z
DTEND:20141008T143000Z
UID:TALK55190@talks.cam.ac.uk
CONTACT:39214
DESCRIPTION:Intrinsically disordered proteins (IDPs) are prevalent in macr
 omolecular assemblies and are thought to mediate protein recognition in co
 mplex regulatory processes and signaling pathways. The formation of a poly
 bivalent scaffold is a key process by which IDPs drive early steps in macr
 omolecular assemblies. Three intrinsically disordered proteins\, IC\, Swal
 low and Nup159\, are core components\, respectively\, of cytoplasmic dynei
 n\, bicoid mRNA localization apparatus\, and nuclear pore complexes. In al
 l three systems\, the hub protein LC8 recognizes on the IDP\, short linear
  motifs that are fully disordered in the apo form\, but adopt a β-strand 
 when bound to LC8. The IDP/LC8 complex forms a bivalent scaffold primed to
  bind additional bivalent ligands.  Scaffold formation also promotes self-
 association and/or higher order organization of the IDP components at a si
 te distant from LC8 binding. Rigorous thermodynamic analyses imply that as
 sociation of additional bivalent ligands is driven by entropic effects whe
 re the first binding event is weak but subsequent binding of additional li
 gands occur with higher affinity. I will present specific examples of macr
 omolecular assemblies in which polybivalency of aligned IDP duplexes not o
 nly enhances binding affinity and results in formation of a stable complex
  but also compensates unfavorable steric and enthalpic interactions. We pr
 opose that polybivalent scaffold assembly involving IDPs and LC8-like prot
 eins is a general process in the cell biology of a class of multi-protein 
 structures that are stable yet fine-tuned for diverse cellular requirement
 s.
LOCATION:Unilever  Lecture Theatre\,  Department of Chemistry
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