@article{706c3140eeb141cf84722e6575345f1c,
title = "Direct regulation of p190RhoGEF by activated Rho and Rac GTPases",
abstract = "Rho family GTPases regulate a wide range of cellular processes. This includes cellular dynamics where three subfamilies, Rho, Rac, and Cdc42, are known to regulate cell shape and migration though coordinate action. Activation of Rho proteins largely depends on Rho Guanine nucleotide Exchange Factors (RhoGEFs) through a catalytic Dbl homology (DH) domain linked to a pleckstrin homology (PH) domain that subserves various functions. The PH domains from Lbc RhoGEFs, which specifically activate RhoA, have been shown to bind to activated RhoA. Here, p190RhoGEF is shown to also bind Rac1·GTP. Crystal structures reveal that activated Rac1 and RhoA use their effector-binding surfaces to associate with the same hydrophobic surface on the PH domain. Both activated RhoA and Rac1 can stimulate exchange of nucleotide on RhoA by localization of p190RhoGEF to its substrate, RhoA·GDP, in vitro. The binding of activated RhoA provides a mechanism for positive feedback regulation as previously proposed for the family of Lbc RhoGEFs. In contrast, the novel interaction between activated Rac1 and p190RhoGEF reveals a potential mechanism for cross-talk regulation where Rac can directly effect stimulation of RhoA. The greater capacity of Rac1 to stimulate p190RhoGEF among the Lbc RhoGEFs suggests functional specialization.",
keywords = "Crosstalk, Crystal structure, GTPase, Membrane localization, PH domain, RhoGEF",
author = "Olugbenga Dada and Stephen Gutowski and Brautigam, {Chad A.} and Zhe Chen and Sternweis, {Paul C.}",
note = "Funding Information: We thank Jana Hadas and Thomas Scheuermann for technical assistance, and the staff of APS for assistance with data collection. This work was supported by National Institute of Health Grants GM31954 (to P. C. S.), and the Alfred and Mabel Gilman Chair in Molecular Pharmacology (P. C. S.). Some results shown in this report are derived from work performed at Argonne National Laboratory, Structural Biology Center at APS. Argonne is operated by U Chicago Argonne, LLC, for the U.S. Department of Energy, Office of Biological and Environmental Research under Contract DE-AC02-06CH11357. Funding Information: The binding affinity between the PH domain of p190RhoGEF and RhoA•GTPγS was determined by isothermal titration calorimetry (ITC) where p190-PH was titrated into a sample cell containing activated RhoA ( Fig. 1 B). Analysis of the data indicates that the binding affinity for this interaction is about 2 μM (1.7 μM–2.6 μM, 68.3% confidence intervals). This value of affinity was supported by analytical ultracentrifugation (AUC) ( Fig. S1 ). Determinations of binding affinities between the PH domains of other Lbc family RhoGEFs and RhoA•GTPγS were also measured by ITC and varied about 10-fold (PRG-PH, 1.2 μM; AKAP-Lbc-PH, 3.1 μM; p114-PH, 13 μM), while measurements by competitive binding showed domains with lower affinity extend this range to about 100 fold (see Fig. 1 in Chen et al. (Submitted for publication) ). Publisher Copyright: {\textcopyright} 2017 Elsevier Inc.",
year = "2018",
month = apr,
doi = "10.1016/j.jsb.2017.11.014",
language = "English (US)",
volume = "202",
pages = "13--24",
journal = "Journal of Structural Biology",
issn = "1047-8477",
publisher = "Academic Press Inc.",
number = "1",
}