dc.contributor.authorBosch, Dustin E.
dc.contributor.authorWillard, Francis S.
dc.contributor.authorRamanujam, Ravikrishna.
dc.contributor.authorKimple, Adam J.
dc.contributor.authorWillard, Melinda D.
dc.contributor.authorNaqvi, Naweed Issak.
dc.contributor.authorSiderovski, David P.
dc.identifier.citationBosch, D. E., Willard, F. S., Ramanujam, R., Kimple, A. J., Willard, M. D., Naqvi, N. I., et al. (2012). A P-loop mutation in Gα subunits prevents transition to the active state: Implications for G-protein signaling in fungal pathogenesis. PLoS Pathogens, 8(2), e1002553.en_US
dc.description.abstractHeterotrimeric G-proteins are molecular switches integral to a panoply of different physiological responses that many organisms make to environmental cues. The switch from inactive to active Gαβγ heterotrimer relies on nucleotide cycling by the Gα subunit: exchange of GTP for GDP activates Gα, whereas its intrinsic enzymatic activity catalyzes GTP hydrolysis to GDP and inorganic phosphate, thereby reverting Gα to its inactive state. In several genetic studies of filamentous fungi, such as the rice blast fungus Magnaporthe oryzae, a G42R mutation in the phosphate-binding loop of Gα subunits is assumed to be GTPase-deficient and thus constitutively active. Here, we demonstrate that Gα(G42R) mutants are not GTPase deficient, but rather incapable of achieving the activated conformation. Two crystal structure models suggest that Arg-42 prevents a typical switch region conformational change upon Gαi1(G42R) binding to GDP·AlF4− or GTP, but rotameric flexibility at this locus allows for unperturbed GTP hydrolysis. Gα(G42R) mutants do not engage the active state-selective peptide KB-1753 nor RGS domains with high affinity, but instead favor interaction with Gβγ and GoLoco motifs in any nucleotide state. The corresponding Gαq(G48R) mutant is not constitutively active in cells and responds poorly to aluminum tetrafluoride activation. Comparative analyses of M. oryzae strains harboring either G42R or GTPase-deficient Q/L mutations in the Gα subunits MagA or MagB illustrate functional differences in environmental cue processing and intracellular signaling outcomes between these two Gα mutants, thus demonstrating the in vivo functional divergence of G42R and activating G-protein mutants.en_US
dc.relation.ispartofseriesPLoS pathogensen_US
dc.rights© 2012 The Authors. This paper was published in PLoS Pathogens and is made available as an electronic reprint (preprint) with permission of The Authors. The paper can be found at the following official DOI: [http://dx.doi.org/10.1371/journal.ppat.1002553]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.en_US
dc.subjectDRNTU::Science::Biological sciences
dc.titleA P-loop mutation in Gα subunits prevents transition to the active state : implications for G-protein signaling in fungal pathogenesisen_US
dc.typeJournal Article
dc.contributor.schoolSchool of Biological Sciencesen_US
dc.description.versionPublished versionen_US

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