[Apologies for multiple postings]

*    GRAND Seminar


Role of promiscuous binding and intrinsic disorder
in protein interactions


12:00 noon, October 27, Tuesday, 2009, ENGR 4201


Anna Panchenko
Associate Investigator


Amarda Shehu


Cellular processes are highly interconnected and many proteins are
shared in different pathways. Some of these shared proteins or protein
families may interact with diverse partners using the same interface
regions. Analysis of such regions is essential for understanding the
mechanisms of specific molecular recognition of multiple diverse
partners. We find that only 5% of protein families in the structure
database have multibinding interfaces, and they do not show any higher
sequence conservation compared with the background interface sites. We
highlight several important functional mechanisms utilized by
multibinding families. Promiscuous interactions can also be studied by
using our recently developed IBIS server (Inferred Biomolecular
Interaction Server,
which analyzes and annotates the interaction partners and locations of
binding sites in proteins.

It has been suggested that intrinsic disorder contributes to the ability
of some proteins to interact with multiple partners as folding of
disordered proteins into ordered structures may occur upon binding to
their specific partners.We performed a large-scale study of
intrinsically disordered regions in proteins and protein complexes. In
accordance with the conventional view that folding and binding are
coupled, in many of our cases the disorder-to-order transition occurs
upon complex formation and can be localized to binding interfaces.
Moreover, analysis of disorder in protein complexes depicts a
significant fraction of intrinsically disordered regions, with up to one
third of all residues being disordered. We find that the disorder in
homodimers, especially in symmetrical homodimers, is significantly
higher than in heterodimers and offer an explanation for this
interesting phenomenon. The fascinating diversity of roles of disordered
regions in various biological processes and protein oligomeric forms
shown in our study is an important subject for future endeavors in this

*Jyh-Ming Lien*
Assistant Professor, George Mason University