The 14-3-3 proteins associate with the plant plasma membrane H(+)-ATPase to generate a fusicoccin binding complex and a fusicoccin responsive system.
The plasma membrane H(+)-ATPase in higher plants has been implicated in nutrient uptake, phloem loading, elongation growth and establishment of turgor. Although a C-terminal regulatory domain has been identified, little is known about the physiological factors involved in controlling the activity of the enzyme. To identify components which play a role in the regulation of the plant H(+)-ATPase, a fusicoccin responsive yeast expressing Arabidopsis plasma membrane H(+)-ATPase AHA2 was employed. By testing the fusicoccin binding activity of yeast membranes, the C-terminal regulatory domain of AHA2 was found to be part of a functional fusicoccin receptor, a component of which was the 14-3-3 protein. ATP hydrolytic activity of AHA2 expressed in yeast internal membranes was activated by all tested isoforms of the 14-3-3 protein of yeast and Arabidopsis, but only in the presence of fusicoccin, and activation was prevented by a phosphoserine peptide representing a known 14-3-3 protein binding motif in Raf-1. The results demonstrate that the 14-3-3 protein is an activator molecule of the H(+)-ATPase and provides the first evidence of a protein involved in activation of plant plasma membrane H(+)-ATPase.
Department of Plant Biology, Royal Veterinary and Agricultural University, Frederiksberg C, Denmark.
L
L
Baunsgaard
A T
AT
Fuglsang
T
T
Jahn
H A
HA
Korthout
A H
AH
de Boer
M G
MG
Palmgren
D048948:14-3-3 Proteins; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics; D001483:Base Sequence; D002462:Cell Membrane / Q000201:enzymology; D017931:DNA Primers / Q000235:genetics; D004789:Enzyme Activation / Q000187:drug effects; D006027:Glycosides / Q000378:metabolism* / Q000494:pharmacology; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D006180:Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D014446:Tyrosine 3-Monooxygenase
D048948:14-3-3 Proteins; D017931:DNA Primers; D006027:Glycosides; D010446:Peptide Fragments; D010940:Plant Proteins; D011506:Proteins; D011956:Receptors, Cell Surface; C080425:fusicoccin receptor protein, plant; C007808:fusicoccin; D014446:Tyrosine 3-Monooxygenase; D006180:Proton-Translocating ATPases