A tomato ER-type Ca2+-ATPase, LCA1, has a low thapsigargin-sensitivity and can transport manganese.
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.
Johnson
Neil A
NA
Division of Biomedical Sciences and Cell Biology & Physiology Section, School of Biological Sciences, Illinois State University, 210 Julian Hall, Campus Box 4120, Normal, IL 61790-4120, USA.
Liu
Fengli
F
Weeks
Phillip D
PD
Hentzen
Audrey E
AE
Kruse
Hilary P
HP
Parker
Jennifer J
JJ
Laursen
Mette
M
Nissen
Poul
P
Costa
Charles J
CJ
Gatto
Craig
C
D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000378:metabolism; D017360:Arabidopsis / Q000201:enzymology; D029681:Arabidopsis Proteins / Q000235:genetics; D001692:Biological Transport; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D017931:DNA Primers; D004721:Endoplasmic Reticulum / Q000201:enzymology*; D005816:Genetic Complementation Test; D007211:Indoles / Q000494:pharmacology; D007700:Kinetics; D018551:Solanum lycopersicum / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development; D008345:Manganese / Q000378:metabolism* / Q000494:pharmacology; D008958:Models, Molecular; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D011487:Protein Conformation; D019284:Thapsigargin / Q000494:pharmacology*
D029681:Arabidopsis Proteins; D017931:DNA Primers; D007211:Indoles; D010940:Plant Proteins; D008345:Manganese; D019284:Thapsigargin; D000251:Adenosine Triphosphatases; D000252:Calcium-Transporting ATPases; C120057:LCA1 protein, Lycopersicon esculentum; C000543:cyclopiazonic acid