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Activation of the plant plasma membrane H+‐ATPase. Is there a direct interaction between lysophosphatidylcholine and the C‐terminal part of the enzyme?
Author(s) -
Gomés Eric,
Kees Venema,
Francoise Simon-Plas,
Marie-Louise Milat,
Michael Gjedde Palmgren,
Jean-Pierre Blein
Publication year - 1996
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(96)01218-5
Subject(s) - lysophosphatidylcholine , enzyme , atpase , biochemistry , chemistry , yeast , arabidopsis thaliana , membrane , enzyme assay , mutant , phosphatidylcholine , gene , phospholipid
The antagonistic effects of the fungal toxin beticolin1 and of l ‐α‐lysophosphatidylcholine (lysoPC) were investigated on the plasma membrane H+‐ATPase of the plant Arabidopsis thaliana (isoform 2) expressed in yeast, using both wild‐type enzyme (AHA2) and C‐terminal truncated enzyme (aha2Δ92). Phosphohydrolytic activities of both enzymes were inhibited by beticolin‐1, with very similar 50% inhibitory concentrations, indicating that the toxin action does not involve the C‐terminal located autoinhibitory domain of the proton pump. Egg lysoPC, a compound that activates the H+‐ATPase by a mechanism involving the C‐terminal part of the protein, was found to be able to reverse the inhibition of AHA2 by beticolin‐1. The lack of effect of other detergents and the comparison of different carbon chain length lysoPCs show that the capacity to reverse the enzyme inhibition is clearly related to their ability to activate the pump. Long chain length lysoPC was also shown to reverse the inhibition of aha2A92 by beticolin‐1, which strongly suggests that lysoPC binds to the H+‐ATPase on site(s) not located on its autoinhibitory domain.