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SUMMARY:Phase behavior of intrinsically disordered proteins and implicatio
 ns for specificity in DNA binding - Prof. Rohit V. Pappu\, Department of B
 iomedical Engineering and Director\, Center for Biological Systems Enginee
 ring\, Washington University\, St. Louis\, USA
DTSTART:20110715T150000Z
DTEND:20110715T160000Z
UID:TALK32095@talks.cam.ac.uk
CONTACT:M. Madan Babu
DESCRIPTION:Intrinsically disordered proteins (IDPs) adopt heterogeneous e
 nsembles of conformations under physiological conditions. This talk will p
 resent a report on our progress toward understanding the\nrelationship bet
 ween amino acid sequence and conformational ensembles of IDPs to clarify t
 he role of disorder in physiological function. Using a combination of poly
 mer physics theories\,\natomistic simulations\, and fluorescence-based exp
 eriments we have quantified the preference of\narchetypal IDP sequences fo
 r globules versus coils. We have shown that polar tracts\, which are seque
 nces that are devoid of canonical hydrophobic residues\, can form compact 
 albeit heterogeneous\ndistributions of globules and that the net charge pe
 r residue is a useful order parameter that separates coil-forming sequence
 s from those that form globules. This has yielded a predictive phase diagr
 am\nthat is guiding further studies regarding the phase behavior of IDPs.\
 n\nWe have also made progress toward understanding the functional implicat
 ions of disorder in DNA binding / transcription. In the second half of thi
 s talk\, I will also provide a report on basic region\nleucine zippers (bZ
 IPs)\, which are archetypal transcription factors that form 2:1 complexes 
 with their cognate DNA. Through a combination of atomistic simulations and
  circular dichroism studies we have\ncharacterized the unbound\, monomeric
  ensembles for these proteins. This effort has\nyielded mechanistic insigh
 ts regarding the role of disorder in facilitating the oft-quoted advantage
  of IDPs in molecular recognition namely\, achieving a high degree of spec
 ificity with low overall\naffinity.\n
LOCATION:Structural Studies Seminar Room\, MRC Laboratory of Molecular Bio
 logy\, Cambridge\, UK
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