Do 14-3-3 proteins and plasma membrane H+-AtPases interact in the barley epidermis in response to the barley powdery mildew fungus?
14-3-3 proteins form a family of highly conserved proteins with central roles in many eukaryotic signalling networks. In plants, they bind to and activate the plasma membrane H+-ATPase, creating a binding site for the phytotoxin fusicoccin. Barley 14-3-3 transcripts accumulate in the epidermis upon inoculation with the powdery mildew fungus. We have isolated a cDNA encoding a plasma membrane H+-ATPase (HvHAI), which is also induced by powdery mildew attack. The C-terminal domain of this H+-ATPase interacts with 14-3-3 proteins in the yeast two-hybrid system. Inoculation with the powdery mildew fungus, or treatment with fusicoccin, results in an increase in fusicoccin binding ability of barley leaf membranes. Overlay assays show a fungus-induced increase in binding of digoxygenin-labelled 14-3-3 protein to several proteins including a 100 kDa membrane protein, probably the plasma membrane H+-ATPase. These effects are seen specifically in the inoculated epidermis and not in the whole leaf. We propose that 14-3-3 proteins are involved in an epidermis-specific response to the powdery mildew fungus, possibly via an activation of the plasma membrane H+-ATPase.
Finni
Christine
C
Department of Plant Biology, Royal Veterinary and Agricultural University, Copenhagen, Denmark.
Andersen
Claus H
CH
Borch
Jonas
J
Gjetting
Sisse
S
Christensen
Anders B
AB
de Boer
A H
AH
Thordal-Christensen
Hans
H
Collinge
David B
DB
D048948:14-3-3 Proteins; D000595:Amino Acid Sequence; D001203:Ascomycota / Q000254:growth & development; D001665:Binding Sites; D018506:Gene Expression Regulation, Plant; D006027:Glycosides / Q000378:metabolism; D001467:Hordeum / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010935:Plant Diseases / Q000382:microbiology; D019441:Plant Epidermis / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D006180:Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D020798:Two-Hybrid System Techniques; D014446:Tyrosine 3-Monooxygenase / Q000235:genetics / Q000378:metabolism*
D048948:14-3-3 Proteins; D006027:Glycosides; D008565:Membrane Proteins; C007808:fusicoccin; D014446:Tyrosine 3-Monooxygenase; D006180:Proton-Translocating ATPases