TPCK inhibits AGC kinases by direct activation loop adduction at phenylalanine-directed cysteine residues.

Rana Anjum, Eunice Pae, John Blenis, Bryan A Ballif

FEBS letters 2012 Sep 21

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N-alpha-tosyl-L-phenylalanyl chloromethyl ketone (TPCK) has anti-tumorigenic properties, but its direct cellular targets are unknown. Previously, we showed TPCK inhibited the PDKl-dependent AGC kinases RSK, Akt and S6K1 without inhibiting PKA, ERK1/2, PI3K, and PDK1 itself. Here we show TPCK-inhibition of the RSK-related kinases MSK1 and 2, which can be activated independently of PDK1. Mass spectrometry analysis of RSK1, Aktl, S6K1 and MSK1 immunopurified from TPCK-treated cells identified TPCK adducts on cysteines located in conserved activation loop Phenylalanine-Cysteine (Phe-Cys) motifs. Mutational analysis of the Phe-Cys residues conferred partial TPCK resistance. These studies elucidate a primary mechanism by which TPCK inhibits several AGC kinases, inviting consideration of TPCK-like compounds in chemotherapy given their potential for broad control of cellular growth, proliferation and survival. Copyright © 2012 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Citation

Rana Anjum, Eunice Pae, John Blenis, Bryan A Ballif. TPCK inhibits AGC kinases by direct activation loop adduction at phenylalanine-directed cysteine residues. FEBS letters. 2012 Sep 21;586(19):3471-6