title: Characterization of the plasma membrane H+-ATPase in the liverwort Marchantia polymorpha.
abstract: The plasma membrane H(+)-ATPase generates an electrochemical gradient of H(+) across the plasma membrane that provides the driving force for solute transport and regulates pH homeostasis and membrane potential in plant cells. Recent studies have demonstrated that phosphorylation of the penultimate threonine in H(+)-ATPase and subsequent binding of a 14-3-3 protein is the major common activation mechanism for H(+)-ATPase in vascular plants. However, there is very little information on the plasma membrane H(+)-ATPase in nonvascular plant bryophytes. Here, we show that the liverwort Marchantia polymorpha, which is the most basal lineage of extant land plants, expresses both the penultimate threonine-containing H(+)-ATPase (pT H(+)-ATPase) and non-penultimate threonine-containing H(+)-ATPase (non-pT H(+)-ATPase) as in the green algae and that pT H(+)-ATPase is regulated by phosphorylation of its penultimate threonine. A search in the expressed sequence tag database of M. polymorpha revealed eight H(+)-ATPase genes, designated MpHA (for M. polymorpha H(+)-ATPase). Four isoforms are the pT H(+)-ATPase; the remaining isoforms are non-pT H(+)-ATPase. An apparent 95-kD protein was recognized by anti-H(+)-ATPase antibodies against an Arabidopsis (Arabidopsis thaliana) isoform and was phosphorylated on the penultimate threonine in response to the fungal toxin fusicoccin in thalli, indicating that the 95-kD protein contains pT H(+)-ATPase. Furthermore, we found that the pT H(+)-ATPase in thalli is phosphorylated in response to light, sucrose, and osmotic shock and that light-induced phosphorylation depends on photosynthesis. Our results define physiological signals for the regulation of pT H(+)-ATPase in the liverwort M. polymorpha, which is one of the earliest plants to acquire pT H(+)-ATPase.
authors.affiliation: Division of Biological Science, Graduate School of Science, Nagoya University, Aichi, Nagoya, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Okumura
authors.forename: Shin-ichiro
authors.initials: S
authors.lastname: Inoue
authors.forename: Koji
authors.initials: K
authors.lastname: Takahashi
authors.forename: Kimitsune
authors.initials: K
authors.lastname: Ishizaki
authors.forename: Takayuki
authors.initials: T
authors.lastname: Kohchi
authors.forename: Toshinori
authors.initials: T
authors.lastname: Kinoshita
mesh_terms: D048948:14-3-3 Proteins / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics; D002462:Cell Membrane / Q000201:enzymology* / Q000235:genetics; D020224:Expressed Sequence Tags; D017343:Genes, Plant; D006027:Glycosides / Q000494:pharmacology; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008027:Light; D008358:Mannose / Q000494:pharmacology; D047008:Marchantia / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000528:radiation effects; D008387:Marine Toxins; D008969:Molecular Sequence Data; D009997:Osmotic Pressure; D010080:Oxazoles / Q000494:pharmacology; D010766:Phosphorylation; D010788:Photosynthesis; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D013395:Sucrose / Q000494:pharmacology; D013912:Threonine / Q000737:chemistry
chemical_list: D048948:14-3-3 Proteins; D006027:Glycosides; D007527:Isoenzymes; D008387:Marine Toxins; D010080:Oxazoles; D010940:Plant Proteins; C007808:fusicoccin; D013912:Threonine; D013395:Sucrose; C059041:calyculin A; D006180:Proton-Translocating ATPases; D008358:Mannose