C-terminal deletion analysis of plant plasma membrane H(+)-ATPase: yeast as a model system for solute transport across the plant plasma membrane.
The plasma membrane proton pump (H(+)-ATPase) energizes solute uptake by secondary transporters. Wild-type Arabidopsis plasma membrane H(+)-ATPase (AHA2) and truncated H(+)-ATPase lacking 38, 51, 61, 66, 77, 92, 96, and 104 C-terminal amino acids were produced in yeast. All AHA2 species were correctly targeted to the yeast plasma membrane and, in addition, accumulated in internal membranes. Removal of 38 C-terminal residues from AHA2 produced a high-affinity state of plant H(+)-ATPase with a low Km value (0.1 mM) for ATP. Removal of an additional 12 amino acids from the C terminus resulted in a significant increase in molecular activity of the enzyme. There was a close correlation between molecular activity of the various plant H(+)-ATPase species and their ability to complement mutants of the endogenous yeast plasma membrane H(+)-ATPase (pma1). This correlation demonstrates that, at least in this heterologous host, activation of H(+)-ATPase is a prerequisite for proper energization of the plasma membrane.
Regenberg
B
B
Department of Plant Biology, Royal Veterinary and Agricultural University, Copenhagen, Denmark.
Villalba
J M
JM
Lanfermeijer
F C
FC
Palmgren
M G
MG
D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D001693:Biological Transport, Active; D002462:Cell Membrane / Q000201:enzymology; D018744:DNA, Plant / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D018390:Gene Targeting; D017343:Genes, Plant; D005816:Genetic Complementation Test; D008954:Models, Biological; D008969:Molecular Sequence Data; D010944:Plants / Q000201:enzymology* / Q000235:genetics*; D006180:Proton-Translocating ATPases / Q000235:genetics* / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D017384:Sequence Deletion
D018744:DNA, Plant; D006180:Proton-Translocating ATPases