Assessing Energetic Contributions to Binding from a Disordered Region in a Protein-Protein Interaction

Journal Article · Sat Dec 31 04:00:00 EST 2011 · Biochemistry (Eaton)

OSTI ID:1041944

Cho, S; Swaminathan, C; Bonsor, D; Kerzic, M; Guan, R; Yang, J; Kieke, C; Anderson, P; Kranz, D

Many functional proteins are at least partially disordered prior to binding. Although the structural transitions upon binding of disordered protein regions can influence the affinity and specificity of protein complexes, their precise energetic contributions to binding are unknown. Here, we use a model protein-protein interaction system in which a locally disordered region has been modified by directed evolution to quantitatively assess the thermodynamic and structural contributions to binding of disorder-to-order transitions. Through X-ray structure determination of the protein binding partners before and after complex formation and isothermal titration calorimetry of the interactions, we observe a correlation between protein ordering and binding affinity for complexes along this affinity maturation pathway. Additionally, we show that discrepancies between observed and calculated heat capacities based on buried surface area changes in the protein complexes can be explained largely by heat capacity changes that would result solely from folding the locally disordered region. Previously developed algorithms for predicting binding energies of protein-protein interactions, however, are unable to correctly model the energetic contributions of the structural transitions in our model system. While this highlights the shortcomings of current computational methods in modeling conformational flexibility, it suggests that the experimental methods used here could provide training sets of molecular interactions for improving these algorithms and further rationalizing molecular recognition in protein-protein interactions.

• Research Organization: BROOKHAVEN NATIONAL LABORATORY (BNL)
• Sponsoring Organization: USDOE SC OFFICE OF SCIENCE (SC)
• DOE Contract Number: AC02-98CH10886
• OSTI ID: 1041944
• Report Number(s): BNL--97622-2012-JA
• Journal Information: Biochemistry (Eaton), Journal Name: Biochemistry (Eaton) Journal Issue: 43 Vol. 49; ISSN 0006-2960; ISSN BICHAW
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
60 APPLIED LIFE SCIENCES
AFFINITY
ALGORITHMS
CALORIMETRY
FLEXIBILITY
FUNCTIONALS
PROTEINS
SIMULATION
SPECIFIC HEAT
SPECIFICITY
SURFACE AREA
THERMODYNAMICS
TITRATION
TRAINING