Methylation of the C-terminal leucine residue of the PP2A catalytic subunit is unnecessary for the catalytic activity and the binding of regulatory subunit (PR55/B).
Protein phosphatase 2A (PP2A) is composed of structural (A), catalytic (C), and regulatory (B) subunits. The catalytic subunit (PP2A(C)) undergoes reversible carboxyl-methylation and -demethylation at its C-terminal leucine residue (Leu309), catalyzed by PP2A-methyltransferase (PMT) and PP2A methylesterase (PME-1), respectively. In this study, we observed that the activity of PP2A was largely unaffected by the addition of PME-1, and that the regulatory subunit (PR55/B) could bind demethylated PP2A(D). Furthermore, to study the precise effect of Leu309 demethylation on PP2A activity, we generated two His(8)-tagged mutant versions of PP2A(C) containing an alanine residue in place of Leu309, and a deletion of Leu309. Both recombinant mutants exhibited phosphatase activity. In addition, we demonstrated that both mutants could constitute a holoenzyme with the regulatory A and B subunits. Our collective results indicate that methylation of Leu309 of PP2A(C) is unnecessary for the PP2A activity and the binding of PR55/B.
Ikehara
Tsuyoshi
T
Tropical Technology Center Ltd, 5-1 Suzaki, Uruma, Okinawa, Japan. tikehara@ttc.co.jp
Ikehara
Satsuki
S
Imamura
Shihoko
S
Shinjo
Fukiko
F
Yasumoto
Takeshi
T
D000595:Amino Acid Sequence; D002265:Carboxylic Ester Hydrolases / Q000037:antagonists & inhibitors / Q000378:metabolism; D002384:Catalysis; D020035:Holoenzymes / Q000378:metabolism; D006801:Humans; D007930:Leucine / Q000378:metabolism*; D008745:Methylation; D009154:Mutation; D019319:Okadaic Acid / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D054648:Protein Phosphatase 2; D011994:Recombinant Proteins / Q000378:metabolism
D020035:Holoenzymes; D011994:Recombinant Proteins; D019319:Okadaic Acid; D002265:Carboxylic Ester Hydrolases; C119357:protein phosphatase methylesterase-1; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2; D007930:Leucine