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Probing the role of allostery in Rho and Ras GTPases
Author(s) -
Marcus Kendra,
Ma Buyong,
Nussinov Ruth,
Mattos Carla
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.761.4
Subject(s) - rhoa , gtpase , hras , allosteric regulation , ras superfamily , subfamily , effector , microbiology and biotechnology , mutant , biology , guanine nucleotide exchange factor , rhoc , biophysics , chemistry , signal transduction , mutation , gtp' , biochemistry , gene , receptor , kras , enzyme
The Ras superfamily of GTPases is a family of binary molecular switches that regulate a variety of cellular processes, such as proliferation and morphological control. Many members of the Ras superfamily are localized to membrane environments and interact with a variety of effectors to promote unique signaling consequences. Due to the strong correlation of Ras GTPases to cancer, the structural, biophysical, and functional relationships of Ras subfamily GTPases have been extensively studied. In particular, our work has identified functionally‐related networks of allosteric communication across the G domain of HRas. Several networks involve water‐mediated connectivity from the active site of the HRas to remote surfaces of the protein that are proposed to interact with the plasma membrane. Like Ras GTPase subfamily members, Rho GTPases are localized within a plasma membrane environment, but contain an inserted helical region located near its active site. We are currently investigating whether these networks are also important in the Rho subfamily of GTPases, with focus on family member RhoA. We have obtained crystal structures of WT RhoA and of two of its mutants, R70A and E102A. These mutants are located within structurally analogous regions of HRas allosteric communication. The solved structures suggest that these mutants promote crystal contacts along switch II of RhoA, an important surface for effector binding. Distal regions of the protein, including the insert helix, also appear to be perturbed. We have also performed accelerated molecular dynamics (aMD) simulations starting with the X‐ray structures for wild type and mutant RhoA. The extended trajectory of the RhoA models (200 ns) highlight the dynamic role of the insert region towards global communication across the RhoA protein. Validated through residue cross‐correlation analysis, both mutants also hinder communication throughout the GTPase, radiating from the active site towards membrane‐interacting regions. These data suggest that global allosteric communication may be a common feature of the Ras superfamily of small GTPases. Support or Funding Information This work is sponsored by a grant from the National Science Foundation (MCB‐1517295)