Binding modes of peptidomimetics designed to inhibit STAT3

Area of Science:

• Biochemistry
• Computational Biology
• Structural Biology

Background:

• STAT3 (Signal Transducer and Activator of Transcription 3) is a transcription factor constitutively activated in many human cancers.
• STAT3 dimerization, mediated by its SH2 domain, promotes anti-apoptotic gene transcription, driving cancer progression.
• Targeting STAT3 dimerization is a promising strategy for cancer therapy, but experimental structures of STAT3 SH2 domain-inhibitor complexes are lacking.

Purpose of the Study:

• To computationally model the binding interactions of 12 peptidomimetic inhibitors with the STAT3 SH2 domain.
• To analyze the binding modes and estimate the binding affinities of these inhibitors.
• To identify potential novel binding interactions for improved inhibitor design.

Main Methods:

• Molecular docking simulations were employed to predict binding poses of inhibitors.
• Molecular dynamics simulations were used to refine the docked structures and assess stability.
• MMPB/GBSA methods combined with entropic calculations were utilized to estimate binding affinities.

Main Results:

• Modeled structures revealed binding interactions consistent with previous studies.
• Estimated binding affinities showed strong correlation with experimentally determined values.
• A novel, stable binding mode was discovered involving SH2 domain loop deformation, which buries the inhibitor's C-terminus.

Conclusions:

• Computational modeling provides valuable insights into STAT3 SH2 domain-inhibitor interactions.
• The identified novel binding mode offers a new avenue for developing potent STAT3 inhibitors.
• This research facilitates the design of next-generation anti-cancer therapeutics targeting STAT3.