Please use this identifier to cite or link to this item: https://doi.org/10.1371/journal.ppat.1002553
Title: A P-loop mutation in G? subunits prevents transition to the active state: Implications for G-protein signaling in fungal pathogenesis
Authors: Bosch D.E.
Willard F.S.
Ramanujam R.
Kimple A.J.
Willard M.D.
Naqvi N.I. 
Siderovski D.P.
Keywords: aluminum derivative
aluminum tetrafluoride
arginine
G protein coupled receptor
guanine nucleotide binding protein
guanosine triphosphatase
kb 1753
unclassified drug
guanine nucleotide binding protein alpha subunit
mutant protein
article
binding affinity
binding site
controlled study
crystal structure
DNA binding motif
fungal strain
fungus
gene locus
gene mutation
hydrolysis
intracellular signaling
nonhuman
pathogenesis
protein conformation
protein protein interaction
signal transduction
amino acid substitution
chemical structure
chemistry
enzyme active site
genetics
Hordeum
Magnaporthe
metabolism
microbiology
mycosis
pathogenicity
physiology
plant disease
plant leaf
point mutation
protein folding
protein tertiary structure
signal transduction
X ray crystallography
Fungi
Magnaporthe grisea
Magnaporthe oryzae
Thespesia grandiflora
Amino Acid Substitution
Catalytic Domain
Crystallography, X-Ray
GTP-Binding Protein alpha Subunits
Hordeum
Magnaporthe
Models, Molecular
Mutant Proteins
Mycoses
Plant Diseases
Plant Leaves
Point Mutation
Protein Folding
Protein Structure, Tertiary
Signal Transduction
Issue Date: 2012
Citation: Bosch D.E., Willard F.S., Ramanujam R., Kimple A.J., Willard M.D., Naqvi N.I., Siderovski D.P. (2012). A P-loop mutation in G? subunits prevents transition to the active state: Implications for G-protein signaling in fungal pathogenesis. PLoS Pathogens 8 (2) : e1002553. ScholarBank@NUS Repository. https://doi.org/10.1371/journal.ppat.1002553
Rights: Attribution 4.0 International
Abstract: Heterotrimeric 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 G??? heterotrimer relies on nucleotide cycling by the G? subunit: exchange of GTP for GDP activates G?, whereas its intrinsic enzymatic activity catalyzes GTP hydrolysis to GDP and inorganic phosphate, thereby reverting G? 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 G? subunits is assumed to be GTPase-deficient and thus constitutively active. Here, we demonstrate that G?(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 G?i1(G42R) binding to GDP·AlF4- or GTP, but rotameric flexibility at this locus allows for unperturbed GTP hydrolysis. G?(G42R) mutants do not engage the active state-selective peptide KB-1753 nor RGS domains with high affinity, but instead favor interaction with G?? and GoLoco motifs in any nucleotide state. The corresponding G?q(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 G? subunits MagA or MagB illustrate functional differences in environmental cue processing and intracellular signaling outcomes between these two G? mutants, thus demonstrating the in vivo functional divergence of G42R and activating G-protein mutants. © 2012 Bosch et al.
Source Title: PLoS Pathogens
URI: https://scholarbank.nus.edu.sg/handle/10635/161643
ISSN: 15537366
DOI: 10.1371/journal.ppat.1002553
Rights: Attribution 4.0 International
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