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Publication Abstract from PubMed

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 alpha subunit (EhGalpha1) signaling from Entamoeba histolytica, the causative agent of amoebic colitis. EhGalpha1 interacts with this effector and guanosine triphosphatase-accelerating protein, EhRGS-RhoGEF, in a nucleotide state-selective fashion. Coexpression of EhRGS-RhoGEF with constitutively active EhGalpha1 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 A 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 EhGalpha1/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.

Structural Determinants of RGS-RhoGEF Signaling Critical to Entamoeba histolytica Pathogenesis.,Bosch DE, Kimple AJ, Manning AJ, Muller RE, Willard FS, Machius M, Rogers SL, Siderovski DP Structure. 2012 Dec 19. pii: S0969-2126(12)00427-3. doi:, 10.1016/j.str.2012.11.012. PMID:23260656^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.