scholarly journals A lipid code-dependent phosphoswitch directs PIN-mediated auxin efflux in Arabidopsis development

2019 ◽  
Author(s):  
Shutang Tan ◽  
Xixi Zhang ◽  
Wei Kong ◽  
Xiao-Li Yang ◽  
Gergely Molnár ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Auxin Transport ◽  
Membrane Composition ◽  
Loss Of Function ◽  
Intercellular Transport ◽  
Lipid Signalling ◽  
External Cues ◽  
Dependent Protein ◽  
Phosphorylation Cascade ◽  
Biochemical Analyses

AbstractDirectional intercellular transport of the phytohormone auxin mediated by PIN FORMED (PIN) efflux carriers plays essential roles in both coordinating patterning processes and integrating multiple external cues by rapidly redirecting auxin fluxes. Multilevel regulations of PIN activity under internal and external cues are complicated; however, the underlying molecular mechanism remains elusive. Here we demonstrate that 3’-Phosphoinositide-Dependent Protein Kinase1 (PDK1), which is conserved in plants and mammals, functions as a molecular hub integrating the upstream lipid signalling and the downstream substrate activity through phosphorylation. Genetic analysis uncovers that loss-of-function Arabidopsis mutant pdk1.1 pdk1.2 exhibits a plethora of abnormalities in organogenesis and growth, due to the defective PIN-dependent auxin transport. Further cellular and biochemical analyses reveal that PDK1 phosphorylates D6 Protein Kinase to facilitate its activity towards PIN proteins. Our studies establish a lipid-dependent phosphorylation cascade connecting membrane composition-based cellular signalling with plant growth and patterning by regulating morphogenetic auxin fluxes.

scholarly journals Loss of cAMP-Dependent Protein Kinase A Affects Multiple Traits Important for Root Pathogenesis by Fusarium oxysporum

2011 ◽  
Vol 24 (6) ◽  
pp. 719-732 ◽  
Author(s):  
Hye-Seon Kim ◽  
Sook-Young Park ◽  
Sangwoo Lee ◽  
Elizabeth L. Adams ◽  
Kirk Czymmek ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Fusarium Oxysporum ◽  
Protein Kinase A ◽  
Vascular System ◽  
Growth Patterns ◽  
Loss Of Function ◽  
Multiple Traits ◽  
Dependent Protein Kinase ◽  
Dependent Protein ◽  
Kinase A

The soilborne fungal pathogen Fusarium oxysporum causes vascular wilt and root rot diseases in many plant species. We investigated the role of cyclic AMP-dependent protein kinase A of F. oxysporum (FoCPKA) in growth, morphology, and root attachment, penetration, and pathogenesis in Arabidopsis thaliana. Affinity of spore attachment to root surfaces of A. thaliana, observed microscopically and measured by atomic force microscopy, was reduced by a loss-of-function mutation in the gene encoding the catalytic subunit of FoCPKA. The resulting mutants also failed to penetrate into the vascular system of A. thaliana roots and lost virulence. Even when the mutants managed to enter the vascular system via physically wounded roots, the degree of vascular colonization was significantly lower than that of the corresponding wild-type strain O-685 and no noticeable disease symptoms were observed. The mutants also had reduced vegetative growth and spore production, and their hyphal growth patterns were distinct from those of O-685. Coinoculation of O-685 with an focpkA mutant or a strain nonpathogenic to A. thaliana significantly reduced disease severity and the degree of root colonization by O-685. Several experimental tools useful for studying mechanisms of fungal root pathogenesis are also introduced.

AMPA receptor phosphorylation during synaptic plasticity

2005 ◽  
Vol 33 (6) ◽  
pp. 1354-1356 ◽  
Author(s):  
J. Boehm ◽  
R. Malinow
Keyword(s):  
Protein Kinase ◽  
Long Term Potentiation ◽  
Synaptic Activity ◽  
Dependent Protein Kinase ◽  
Enhanced Transmission ◽  
Calcium Calmodulin Dependent ◽  
Term Potentiation ◽  
Dependent Protein ◽  
Biochemical Analyses

A widely studied example of vertebrate plasticity is LTP (long-term potentiation), the persistent synaptic enhancement that follows a brief period of coinciding pre- and post-synaptic activity. During LTP, different kinases, including CaMKII (calcium/calmodulin-dependent protein kinase II) and protein kinase A, become activated and play critical roles in induction and maintenance of enhanced transmission. Biochemical analyses have revealed several regulated phosphorylation sites in the AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptor subunits, GluR1 and GluR4. The regulated insertion of these receptors is a key event in the induction of LTP. Here, we discuss the phosphorylation of GluR1 and GluR4 and its role in receptor delivery and neuronal plasticity.

scholarly journals A Viral Double-Stranded RNA Up Regulates the Fungal Virulence of Nectria radicicola

2001 ◽  
Vol 14 (4) ◽  
pp. 496-507 ◽  
Author(s):  
II-Pyung Ahn ◽  
Yong-Hwan Lee
Keyword(s):  
Protein Kinase ◽  
Pathogenic Fungi ◽  
Ginseng Root ◽  
Cdna Clones ◽  
Fungal Virulence ◽  
Double Stranded Rna ◽  
Kinase C ◽  
Causal Fungus ◽  
Dependent Protein ◽  
Biochemical Analyses

Double-stranded RNAs (dsRNAs) are widespread in plant pathogenic fungi, but their functions in fungal hosts remain mostly unclear, with a few exceptions. We analyzed dsRNAs from Nectria radicicola, the causal fungus of ginseng root rot. Four distinct sizes of dsRNAs, 6.0, 5.0, 2.5, and 1.5 kbp, were detected in 24 out of the 81 strains tested. Curing tests of individual dsRNAs suggested that the presence of 6.0-kbp dsRNA was associated with high levels of virulence, sporulation, laccase activity, and pigmentation in this fungus. The 6.0-kbp dsRNA-cured strains completely lost virulence-related phenotypes. This 6.0-kbp dsRNA was reintroduced by hyphal anastomosis to a dsRNA-cured strain marked with hygromycin resistance, which resulted in the restoration of virulence-related phenotypes. These results strongly suggest that 6.0-kbp dsRNA up regulates fungal virulence in N. radicicola. Sequencing of several cDNA clones derived from 6.0-kbp dsRNA revealed the presence of a RNA-dependent RNA polymerase (RDRP) gene. Phylogenetic analysis showed that this gene is closely related to those of plant cryptic viruses. Biochemical analyses suggested that the 6.0-kbp dsRNA may regulate fungal virulence through signal-transduction pathways involving cyclic AMP-dependent protein kinase and protein kinase C.

scholarly journals The sak1+ gene of Schizosaccharomyces pombe encodes an RFX family DNA-binding protein that positively regulates cyclic AMP-dependent protein kinase-mediated exit from the mitotic cell cycle.

1995 ◽  
Vol 15 (3) ◽  
pp. 1479-1488 ◽  
Author(s):  
S Y Wu ◽  
M McLeod
Keyword(s):  
Protein Kinase ◽  
Dna Binding ◽  
Cyclic Amp ◽  
Stationary Phase ◽  
Schizosaccharomyces Pombe ◽  
Sexual Differentiation ◽  
Loss Of Function ◽  
Dependent Protein Kinase ◽  
Dependent Protein ◽  
Diploid Cells

In Schizosaccharomyces pombe, meiosis is initiated by conditions of nutrient deprivation. Mutations in genes encoding elements of the cyclic AMP-dependent protein kinase (cAPK) pathway interfere with meiosis. Loss-of-function alleles of genes that stimulate the activity of cAPK allow cells to bypass the normal requirement of starvation for conjugation and meiosis. Alternatively, loss-of-function alleles of genes that inhibit cAPK lead to the inability to undergo sexual differentiation. The cgs1+ gene encodes the regulatory subunit of cAPK, and the cgs2+ gene encodes a cyclic AMP phosphodiesterase. Thus, both genes encode proteins which negatively regulate the activity of cAPK. Loss of either cgs1 or cgs2 prevents haploid cells from conjugating and diploid cells from undergoing meiosis. In addition to these defects, cells are unable to enter stationary phase. We describe a novel gene, sak1+, which when present on a plasmid overcomes the aberrant phenotypes associated with unregulated cAPK activity. Genetic analysis of sak1+ (suppressor of A-kinase) reveals that it functions downstream of cyclic AMP-dependent protein kinase to allow cells to exist the mitotic cycle and enter either stationary phase or the pathway leading to sexual differentiation. The sak1+ gene is essential for cell viability, and a null allele causes multiple defects in cell morphology and nuclear division. Thus, sak1+ is an important regulatory element in the life cycle of S. pombe. Sequence analysis shows that the predicted product of the sak1+ gene is an 87-kDa protein which shares homology to the RFX family of DNA-binding proteins identified in humans and mice. One member of this family, RFX1, is a transcription factor for a variety of viral and cellular genes.

scholarly journals PDK1 has a pleiotropic PINOID-independent role in Arabidopsis development

2019 ◽  
Author(s):  
Yao Xiao ◽  
Remko Offringa
Keyword(s):  
Auxin Transport ◽  
Primary Root ◽  
Loss Of Function ◽  
In Planta ◽  
Phenotypic Analysis ◽  
Master Regulator ◽  
Dna Insertion ◽  
Dependent Protein ◽  
Eukaryotic Organisms ◽  
Auxin Efflux Carriers

AbstractThe 3-Phosphoinositide-Dependent Protein Kinase 1 (PDK1) is a conserved and important master regulator of AGC kinases in eukaryotic organisms. pdk1 loss-of-function causes a lethal phenotype in animals and yeast. In contrast, only very mild phenotypic defects have been reported for the pdk1 loss-of-function mutant of the model plant Arabidopsis thaliana (Arabidopsis). The Arabidopsis genome contains two PDK1 genes, hereafter called PDK1 and PDK2. Here we show that the previously reported Arabidopsis pdk1 T-DNA insertion alleles are not true loss-of-function mutants. By using CRISPR/Cas9 technology, we created true loss-of-function pdk1 alleles, and pdk1 pdk2 double mutants carrying these alleles showed multiple growth and development defect, including fused cotyledons, a short primary root, dwarf stature, late flowering, and reduced seed production caused by defects in male fertility. Surprisingly, pdk1 pdk2 mutants did not phenocopy pid mutants, and together with the observations that PDK1 overexpression does not phenocopy the effect of PID overexpression, and that pdk1 pdk2 loss-of-function does not change PID subcellular localization, we conclude that PDK1 is not essential for PID membrane localization or functionality in planta. Nonetheless, most pdk1 pdk2 phenotypes could be correlated with impaired auxin transport. PDK1 is highly expressed in vascular tissues and YFP:PDK1 is relatively abundant at the basal/rootward side of root stele cells, where it colocalizes with PIN auxin efflux carriers, and the AGC1 kinases PAX and D6PK/D6PKLs. Our genetic and phenotypic analysis suggests that PDK1 is likely to control auxin transport as master regulator of these AGC1 kinases in Arabidopsis.

The wis1 signal transduction pathway is required for expression of cAMP-repressed genes in fission yeast

1996 ◽  
Vol 109 (7) ◽  
pp. 1927-1935 ◽  
Author(s):  
S. Stettler ◽  
E. Warbrick ◽  
S. Prochnik ◽  
S. Mackie ◽  
P. Fantes
Keyword(s):  
Protein Kinase ◽  
Map Kinase ◽  
Nitrogen Starvation ◽  
Osmotic Shock ◽  
Regulatory Subunit ◽  
Loss Of Function ◽  
Dependent Protein Kinase ◽  
Glucose Limitation ◽  
Camp Dependent Protein Kinase ◽  
Dependent Protein

The wis1 protein kinase of Schizosaccharomyces pombe is a member of the MAP kinase kinase family. Loss of wis1 function has previously been reported to lead to a delay in the G2-mitosis transition, loss of viability in stationary phase, and hypersensitivity to osmotic shock. It acts at least in part by activating the MAP kinase homologue sty1; loss-of-function sty1 mutants share many phenotypes with wis1 deletion mutants. We show here that, in addition, loss of wis1 function leads to defective conjugation, and to suppression of the hyperconjugation phenotype of the pat1-114 mutation. Consistent with this, the induction of the mei2 gene, which is normally induced by nitrogen starvation, is defective in wis1 mutants. In wild-type cells, nitrogen starvation leads to mei2 induction through a fall in intracellular cyclic AMP (cAMP) level and activity of the cAMP-dependent protein kinase. We show here that wis1 function is required for mei2 induction following nitrogen starvation. Expression of the fbp1 gene is negatively regulated by cAMP in response to glucose limitation: induction of fbp1 also requires wis1 and sty1 function. Loss of wis1 is epistatic over increased fbp1 expression brought about by loss of adenylate cyclase (git2/cyr1) or cAMP-dependent protein kinase (pka1) function. These observations can be explained by a model in which the pka1 pathway negatively regulates the wis1 pathway, or the two pathways might act independently on downstream targets. The latter explanation is supported, at least as regards regulation of cell division, by the observation that loss of function of the regulatory subunit of the cAMP-dependent protein kinase (cgs1) brings about a modest increase in cell length at division in both wis1+ and wis1 delta genetic backgrounds.

scholarly journals Myosin 5b loss of function leads to defects in polarized signaling: implication for microvillus inclusion disease pathogenesis and treatment

2014 ◽  
Vol 307 (10) ◽  
pp. G992-G1001 ◽  
Author(s):  
Dmitri Kravtsov ◽  
Anastasia Mashukova ◽  
Radia Forteza ◽  
Maria M. Rodriguez ◽  
Nadia A. Ameen ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Water Flux ◽  
Secretory Diarrhea ◽  
Loss Of Function ◽  
Kinase C ◽  
Primary Location ◽  
Dependent Protein ◽  
Autosomal Recessive Condition ◽  
Myosin Vb ◽  
Net Water Flux

Microvillus inclusion disease (MVID) is an autosomal recessive condition resulting in intractable secretory diarrhea in newborns due to loss-of-function mutations in myosin Vb (Myo5b). Previous work suggested that the apical recycling endosomal (ARE) compartment is the primary location for phosphoinositide-dependent protein kinase 1 (PDK1) signaling. Because the ARE is disrupted in MVID, we tested the hypothesis that polarized signaling is affected by Myo5b dysfunction. Subcellular distribution of PDK1 was analyzed in human enterocytes from MVID/control patients by immunocytochemistry. Using Myo5b knockdown (kd) in Caco-2BBe cells, we studied phosphorylated kinases downstream of PDK1, electrophysiological parameters, and net water flux. PDK1 was aberrantly localized in human MVID enterocytes and Myo5b-deficient Caco-2BBe cells. Two PDK1 target kinases were differentially affected: phosphorylated atypical protein kinase C (aPKC) increased fivefold and phosohoprotein kinase B slightly decreased compared with control. PDK1 redistributed to a soluble (cytosolic) fraction and copurified with basolateral endosomes in Myo5b kd. Myo5b kd cells showed a decrease in net water absorption that could be reverted with PDK1 inhibitors. We conclude that, in addition to altered apical expression of ion transporters, depolarization of PDK1 in MVID enterocytes may lead to aberrant activation of downstream kinases such as aPKC. The findings in this work suggest that PDK1-dependent signaling may provide a therapeutic target for treating MVID.

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