Structural determinants of RGS-RhoGEF signaling critical to Entamoeba histolytica pathogenesis.

ABSTRACT: G protein signaling pathways, as key components of physiologic responsiveness and timing, are frequent targets for pharmacologic intervention. Here, we identify an effector for heterotrimeric G protein ? subunit (EhG?1) signaling from Entamoeba histolytica, the causative agent of amoebic colitis. EhG?1 interacts with this effector and guanosine triphosphatase-accelerating protein, EhRGS-RhoGEF, in a nucleotide state-selective fashion. Coexpression of EhRGS-RhoGEF with constitutively active EhG?1 and EhRacC leads to Rac-dependent spreading in Drosophila S2 cells. EhRGS-RhoGEF overexpression in E. histolytica trophozoites leads to reduced migration toward serum and lower cysteine protease activity, as well as reduced attachment to, and killing of, host cells. A 2.3 Å crystal structure of the full-length EhRGS-RhoGEF reveals a putative inhibitory helix engaging the Dbl homology domain Rho-binding surface and the pleckstrin homology domain. Mutational analysis of the EhG?1/EhRGS-RhoGEF interface confirms a canonical "regulator of G protein signaling" domain rather than a RhoGEF-RGS ("rgRGS") domain, suggesting a convergent evolution toward heterotrimeric and small G protein cross-talk.

SUBMITTER: Bosch DE 

PROVIDER: S-EPMC3545058 | biostudies-literature | 2013 Jan

REPOSITORIES: biostudies-literature