Regulation of plant plasma membrane H⁺‐ATPase activity

Abstract

Paimgren, M.G. 1991. Regulation of plant plasma membrane H+-ATPase activity. -Physiol. Plant. 83: 314-323.The plant plasma membrane H*-ATPase plays a central role in plant physiology. This enzyme belongs to the P type family of cation-translocating pumps and generates the proton-motive force that drives nutrient uptake across the plasma membrane. It also determines the extracellular acidification associated with elongation growth. The activity of the plasma membrane H^-ATPase is rapidly altered after exposure of plant tissues to plant growth factors such as plant hormones, light and pathogens. However, very little is known about the mechanisms that regulate plasma membrane H*-ATPase activity in the intact cell. The recent identification of an auto-inhibitory domain in the C-terminus of the plant plasma membrane H^-ATPase implies that there are several possible means by which the enzyme could be regulated. The inhibitory interaction between the inhibitory domain and the catalytic site and/or a proton binding site may thus be regulated by a variety of means, such as the binding of effector molecules, phosphoryiation, partial proteolysis, or removal of the inhibitory domain at the gene level. In addition, proton pumping across the plasma membrane could be regulated by changes in the transcriptionai activity of H'^-ATPase genes or by differential expression of pump isoforms varying in their C-terminal domain.

Blue light activates the plasma membrane H+-ATPase by phosphorylation of the C-terminus in stomatal guard cells

“…Removal of a 7-10 kDa fragment from the C-terminal end of H ϩ -ATPase generates a high-activity state of H ϩ -ATPase with a higher V max , a lower K m for ATP, a changed pH dependence with higher activity at physiological pH and an increased coupling of H ϩ transport with ATP hydrolysis (Palmgren et al, 1990;Morsomme et al, 1996;Sze et al, 1999). Very similar results were obtained by in vivo treatment of intact tissue with the fungal toxin fusicoccin (FC), an activator of the H ϩ -ATPase, and it is suggested that FC induces a displacement of the C-terminal autoinhibitory domain of H ϩ -ATPase from its catalytic site (Palmgren, 1991;Johansson et al, 1993;Rasi-Caldogno et al, 1993). Such displacement of the C-terminus may be achieved by phosphorylation and dephosphorylation with physiological stimuli, and the C-terminus can be a substrate for protein kinase and protein phosphatase in vivo and in vitro (Schaller and Sussman, 1988;Serrano, 1989;Palmgren, 1991;Suzuki et al, 1992;Sekler et al, 1994;Vera-Estrella et al, 1994;Xing et al, 1996;Camoni et al, 1998;Sze et al, 1999).…”

“…Two mRNAs encoding the H ϩ -ATPase isoproteins (VHA1 and VHA2, Vicia H ϩ -ATPase isoforms 1 and 2) are expressed in Vicia guard cells, and cDNA clones for these have been isolated (Nakajima et al, 1995;Hentzen et al, 1996). Since the plasma membrane H ϩ -ATPase generates a H ϩ electrochemical gradient, and provides a driving force for the uptake of various nutrients such as K ϩ , nitrate, sulfate, sucrose and amino acids across the plasma membrane in many cell types and tissues of plant, the regulatory mechanism of this enzyme has been studied extensively (Serrano, 1989;Palmgren, 1991;Sussman, 1994;Michelet and Boutry, 1995;Sze et al, 1999). The H ϩ -ATPase activity is thought to be regulated by an autoinhibitory domain in the C-terminal region of the enzyme.…”

Complementation in situ of the yeast plasma membrane H+‐ATPase gene pmal by an H+‐ATPase gene from a heterologous species

“…3), it was found that the specific activity of the truncated plant H'-ATPase was 2-3-fold higher than that of wild-type plant H'-ATPase. The pm-bound plant H'-ATPase isolated from plant sources is specifically activated by treatment with the detergent lysophosphatidylcholine (lyso-PC) [3]. Lyso-PC produced a 2-fold increase in the ATPase activity of the wild-type plant H'-ATPase expressed in the ER (Fig.…”

Modulation of Vacuolar H+-Pumps and Aquaporin by Phytohormones in Rice Seedling Leaf Sheaths.

“…The inhibitory interaction between this domain and the ATP-and/or the H ϩ -binding site could be modulated by variety of means, such as binding of effector molecules, phosphorylation, partial proteolysis, or truncation at the gene level. [29][30][31] The vacuolar H ϩ -PPase in Chenopodium rubrum has been reported to be regulated by a lysolipid, 32) and the vacuolar V-ATPase in bovine kidney has been reported to be regulated by regulatory proteins existing in the cytosol. 33) To understand the roles of tonoplast H ϩ -pumps, the intracellular levels of PPi and ATP must be determined.…”