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A tomato ER-type Ca2+-ATPase, LCA1, has a low thapsigargin-sensitivity and can transport manganese

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  • Neil A. Johnson, Illinois State University in Normal, USA
  • F Liu, Illinois State University in Normal, USA
  • P. D. Weeks, Illinois State University in Normal, USA
  • A. E. Hentzen, Illinois State University in Normal, USA
  • H. P. Kruse, Illinois State University in Normal, USA
  • J. J. Parker, Illinois State University in Normal, USA
  • Mette Laursen
  • Poul Nissen
  • C. J. Costa, Illinois State University in Normal, USA
  • Craig Gatto, Illinois State University in Normal, USA
  • Molekylærbiologisk Institut
Recombinant Ca(2+)-ATPase from tomato (i.e. LCA1 for Lycopersicon esculentum [Since the identification and naming of LCA1, the scientific name for the tomato has been changed to Solanum lycopersicum.] Ca-ATPase) was heterologously expressed in yeast for structure-function characterization. We investigate the differences between plant and animal Ca pumps utilizing comparisons between chicken and rabbit SERCA-type pumps with Arabidopsis (ECA1) and tomato plant (LCA1) Ca(2+)-ATPases. Enzyme function was confirmed by the ability of each Ca(2+)-ATPase to rescue K616 growth on EGTA-containing agar and directly via in vitro ATP hydrolysis. We found LCA1 to be approximately 300-fold less sensitive to thapsigargin than animal SERCAs, whereas ECA1 was thapsigargin-resistant. LCA1 showed typical pharmacological sensitivities to cyclopiazonic acid, vanadate, and eosin, consistent with it being a P(IIA)-type Ca(2+)-ATPase. Possible amino acid changes responsible for the reduced plant thapsigargin-sensitivity are discussed. We found that LCA1 also complemented K616 yeast growth in the presence of Mn(2+), consistent with moving Mn(2+) into the secretory pathway and functionally compensating for the lack of secretory pathway Ca-ATPases (SPCAs) in plants.
OriginalsprogEngelsk
TidsskriftArchives of Biochemistry and Biophysics
Vol/bind481
Nummer2
Sider (fra-til)157-168
ISSN0003-9861
StatusUdgivet - 20 nov. 2008

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