G protein α subunit suppresses sporangium formation through a serine/threonine protein kinase in Phytophthora sojae

ABSTRACT For the soybean pathogen Phytophthora sojae, chemotaxis of zoospores to isoflavones is believed to be critical for recognition of the host and for initiating infection. However, the molecular mechanisms underlying this chemotaxis are largely unknown. To investigate the role of G-protein and calcium signaling in chemotaxis, we analyzed the expression of several genes known to be involved in these pathways and selected one that was specifically expressed in sporangia and zoospores but not in mycelium. This gene, named PsGPA1, is a single-copy gene in P. sojae and encodes a G-protein α subunit that shares 96% identity in amino acid sequence with that of Phytophthora infestans. To elucidate the function, expression of PsGPA1 was silenced by introducing antisense constructs into P. sojae. PsGPA1 silencing did not disturb hyphal growth or sporulation but severely affected zoospore behavior, including chemotaxis to the soybean isoflavone daidzein. Zoospore encystment and cyst germination were also altered, resulting in the inability of the PsGPA1-silenced mutants to infect soybean. In addition, the expressions of a calmodulin gene, PsCAM1, and two calcium- and calmodulin-dependent protein kinase genes, PsCMK3 and PsCMK4, were increased in the mutant zoospores, suggesting that PsGPA1 negatively regulates the calcium signaling pathways that are likely involved in zoospore chemotaxis.

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Faculty Opinions recommendation of Structural basis for modulation of gating property of G protein-gated inwardly rectifying potassium ion channel (GIRK) by i/o-family G protein α subunit (Gαi/o).

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.714397808.789952913 ◽

2012 ◽

Author(s):

Nathan Dascal

Keyword(s):

Ion Channel ◽

G Protein ◽

Potassium Ion ◽

Structural Basis ◽

Potassium Ion Channel ◽

Α Subunit ◽

G Protein Α Subunit ◽

Inwardly Rectifying

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Dominant-negative inhibition of pheromone receptor signaling by a single point mutation in the G protein α subunit. Vol. 279 (2004) 35287-35297

Journal of Biological Chemistry ◽

10.1016/s0021-9258(20)56430-2 ◽

2005 ◽

Vol 280 (33) ◽

pp. 29988

Author(s):

Yuh-Lin Wu ◽

Shelley B. Hooks ◽

T. Kendall Harden ◽

Henrik G. Dohlman

Keyword(s):

G Protein ◽

Point Mutation ◽

Single Point ◽

Dominant Negative ◽

Single Point Mutation ◽

Receptor Signaling ◽

Α Subunit ◽

Pheromone Receptor ◽

G Protein Α Subunit

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Genetic Involvement of a cAMP-Dependent Protein Kinase in a G Protein Signaling Pathway Regulating Morphological and Chemical Transitions in Aspergillus nidulans

Genetics ◽

10.1093/genetics/157.2.591 ◽

2001 ◽

Vol 157 (2) ◽

pp. 591-600

Author(s):

Kiminori Shimizu ◽

Nancy P Keller

Keyword(s):

Protein Kinase ◽

Aspergillus Nidulans ◽

Signaling Pathway ◽

G Protein ◽

Radial Growth ◽

Morphological Development ◽

Dependent Protein Kinase ◽

Α Subunit ◽

Camp Dependent Protein Kinase ◽

Dependent Protein

Abstract In the filamentous fungus Aspergillus nidulans, a heterotrimeric G protein α-subunit and an RGS domain protein, encoded by fadA and flbA, respectively, regulate production of the carcinogenic metabolite sterigmatocystin (ST) and asexual spores (i.e., conidia). We investigated the genetic involvement of the cAMP-dependent protein kinase catalytic subunit (PkaA), a potential downstream target of FadA activity, in ST production and conidiation. Relative to wild type, sporulation was decreased in the pkaA overexpression strain but was not totally absent, as occurs in ΔflbA or fadAG42R (fadA-dominant active) strains. Deletion of pkaA resulted in a hyper-conidiating strain with limited radial growth. This phenotype was epistatic to mutation in flbA or fadA; the double mutants ΔpkaA; ΔflbA and ΔpkaA; fadAG42R recovered sporulation and their radial growth was severely restricted. PkaA overexpression also negatively regulated AflR, the ST biosynthesis-specific transcription factor, both transcriptionally and post-transcriptionally. Deletion of pkaA restored ST production in the ΔflbA background but not in the fadAG42R background. These data provide genetic evidence that the FlbA/FadA signaling pathway regulating ST production and morphological development is partially mediated through PkaA.

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The G-Protein α-Subunit GasC Plays a Major Role in Germination in the Dimorphic FungusPenicillium marneffei

Genetics ◽

10.1093/genetics/164.2.487 ◽

2003 ◽

Vol 164 (2) ◽

pp. 487-499 ◽

Cited By ~ 2

Author(s):

Sophie Zuber ◽

Michael J Hynes ◽

Alex Andrianopoulos

Keyword(s):

G Protein ◽

Germination Rate ◽

Yeast Cells ◽

Class Iii ◽

Temperature Dependent ◽

Gene Encoding ◽

Α Subunit ◽

G Protein Α Subunit ◽

Opportunistic Human Pathogen

AbstractThe opportunistic human pathogen Penicillium marneffei exhibits a temperature-dependent dimorphic switch. At 25°, multinucleate, septate hyphae that can undergo differentiation to produce asexual spores (conidia) are produced. At 37° hyphae undergo arthroconidiation to produce uninucleate yeast cells that divide by fission. This work describes the cloning of the P. marneffei gasC gene encoding a G-protein α-subunit that shows high homology to members of the class III fungal Gα-subunits. Characterization of a ΔgasC mutant and strains carrying a dominant-activating gasCG45R or a dominant-interfering gasCG207R allele show that GasC is a crucial regulator of germination. A ΔgasC mutant is severely delayed in germination, whereas strains carrying a dominant-activating gasCG45R allele show a significantly accelerated germination rate. Additionally, GasC signaling positively affects the production of the red pigment by P. marneffei at 25° and negatively affects the onset of conidiation and the conidial yield, showing that GasC function overlaps with functions of the previously described Gα-subunit GasA. In contrast to the S. cerevisiae ortholog Gpa2, our data indicate that GasC is not involved in carbon or nitrogen source sensing and plays no major role in either hyphal or yeast growth or in the switch between these two forms.

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Analysis by mRNA levels of the expression of six G protein α-subunit genes in mammalian cells and tissues

Biochimica et Biophysica Acta (BBA) - Molecular Cell Research ◽

10.1016/0167-4889(91)90008-l ◽

1991 ◽

Vol 1094 (2) ◽

pp. 193-199 ◽

Cited By ~ 34

Author(s):

Jermelina Linor R. Garibay ◽

Tohru Kozasa ◽

Hiroshi Itoh ◽

Toshihiko Tsukamoto ◽

Masaaki Matsuoka ◽

...

Keyword(s):

G Protein ◽

Mammalian Cells ◽

Mrna Levels ◽

Α Subunit ◽

G Protein Α Subunit

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Large G protein α-subunit XLαs limits clathrin-mediated endocytosis and regulates tissue iron levels in vivo

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1712670114 ◽

2017 ◽

Vol 114 (45) ◽

pp. E9559-E9568 ◽

Cited By ~ 5

Author(s):

Qing He ◽

Richard Bouley ◽

Zun Liu ◽

Marc N. Wein ◽

Yan Zhu ◽

...

Keyword(s):

Skeletal Muscle ◽

G Protein ◽

Critical Role ◽

Hek293 Cells ◽

Activity Levels ◽

Α Subunit ◽

Proteomic Screen ◽

Protein Levels ◽

G Protein Α Subunit

Alterations in the activity/levels of the extralarge G protein α-subunit (XLαs) are implicated in various human disorders, such as perinatal growth retardation. Encoded by GNAS, XLαs is partly identical to the α-subunit of the stimulatory G protein (Gsα), but the cellular actions of XLαs remain poorly defined. Following an initial proteomic screen, we identified sorting nexin-9 (SNX9) and dynamins, key components of clathrin-mediated endocytosis, as binding partners of XLαs. Overexpression of XLαs in HEK293 cells inhibited internalization of transferrin, a process that depends on clathrin-mediated endocytosis, while its ablation by CRISPR/Cas9 in an osteocyte-like cell line (Ocy454) enhanced it. Similarly, primary cardiomyocytes derived from XLαs knockout (XLKO) pups showed enhanced transferrin internalization. Early postnatal XLKO mice showed a significantly higher degree of cardiac iron uptake than wild-type littermates following iron dextran injection. In XLKO neonates, iron and ferritin levels were elevated in heart and skeletal muscle, where XLαs is normally expressed abundantly. XLKO heart and skeletal muscle, as well as XLKO Ocy454 cells, showed elevated SNX9 protein levels, and siRNA-mediated knockdown of SNX9 in XLKO Ocy454 cells prevented enhanced transferrin internalization. In transfected cells, XLαs also inhibited internalization of the parathyroid hormone and type 2 vasopressin receptors. Internalization of transferrin and these G protein-coupled receptors was also inhibited in cells expressing an XLαs mutant missing the Gα portion, but not Gsα or an N-terminally truncated XLαs mutant unable to interact with SNX9 or dynamin. Thus, XLαs restricts clathrin-mediated endocytosis and plays a critical role in iron/transferrin uptake in vivo.

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