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New evidence for dimerization of the short variant of PLA2g6, and regulation of its catalytic activity by Ca2+/calmodulin and Ca2+ influx factor.
Author(s) -
Korolev Sergey,
Csutora Peter,
Peter Krisztina,
Koroleva Olga,
Subramanya Praven,
Malley Konstantin,
Bolotina Victoria M
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.1004.5
Subject(s) - calmodulin , dimer , chemistry , biochemistry , microbiology and biotechnology , biophysics , enzyme , biology , organic chemistry
Ca 2+ ‐independent phospholipase A 2 β (PLA2g6) plays important role in cellular function and is associated with a wide spectrum of pathological conditions, but its structure and mechanism of regulation remain poorly understood. Here we used analytical ultracentrifugation method to characterize oligomeric state of recombinant short (S) splice variant of PLA2g6, and an in vitro real‐time fluorescent substrate assay to assess regulation of its catalytic activity by Ca 2+ /calmodulin (CaM) and Ca 2+ influx factor (CIF). Analysis of sedimentation equilibrium revealed that PLA2g6(S) exists as a dimer of an elongated shape, which is stable with ant without Ca 2+ /CaM. We found that PLA2g6 is inhibited by CaM at physiological Ca 2+ concentrations, suggesting that additional factors are needed to dissociate CaM to activate enzyme. We demonstrated that CIF can be one of such physiological factors, as it displaced CaM and activates PLA2g6 at any levels of Ca 2+ (up to 2mM). These studies provide first strict evidence for PLA2g6(S) dimerization, and CIF‐induced full activation of PLA2g6 under physiological Ca 2+ /CaM conditions.