P-Rex family Rho guanine-nucleotide exchange factors are important regulators of cell motility through their activation of a subset of small GTPases. Both P-Rex1 and P-Rex2 have also been implicated in the progression of certain cancers, including breast cancer and melanoma. Although these molecules display a high level of homology, differences exist in tissue distribution, physiological function, and regulation at the molecular level. Here, we sought to compare the P-Rex2 pleckstrin homology (PH) domain structure and ability to interact with PIP3 with those of P-Rex1. The 1.9 Å crystal structure of the P-Rex2 PH domain reveals conformational differences in the loop regions, yet biochemical studies indicate that the interaction of the P-Rex2 PH domain with PIP3 is very similar to that of P-Rex1. Binding of the PH domain to PIP3 is critical for P-Rex2 activity but not membrane localization, as previously demonstrated for P-Rex1. These studies serve as a starting point in the identification of P-Rex structural features that are divergent between isoforms and could be exploited for the design of P-Rex selective compounds.
Keywords: DEP, dishevelled, Egl-10, and pleckstrin; DH, Dbl homology; DSF, differential scanning fluorimetry; DTT, dithiothreitol; EDTA, ethylenediaminetetraacetic; Gβγ, G protein β and γ subunits; IP4P, inositol polyphosphate 4-phosphatase; Ins(1,3,4,5)P4, inositol-1,3,4,5-tetrakisphosphate; MBP, maltose binding protein; P-Rex; P-Rex, phosphatidylinositol 3,4,5-trisphosphate-dependent Rac exchanger; PDZ, post-synaptic density protein, Drosophila disc large tumor suppressor, and zonula occludens-1 protein; PH, pleckstrin homology; PIP3, phosphatidylinositol 3,4,5-trisphosphate; PMSF, phenylmethylsulfonyl fluoride; PTEN, phosphatase and tensin homolog; Phosphatidylinositol 3,4,5-trisphosphate; Pleckstrin homology domain; Rho guanine nucleotide exchange factor; RhoGEF, Rho guanine-nucleotide exchange factor.
© 2018 The Authors.