Conversion of SB 203580-insensitive MAP kinase family members to drug-sensitive forms by a single amino-acid substitution.
BACKGROUND
Specific inhibitors of protein kinases have great therapeutic potential, but the molecular basis underlying their specificity is only poorly understood. We have investigated the drug SB 203580 which belongs to a class of pyridinyl imidazoles that inhibits the stress-activated protein (SAP) kinases SAPK2a/p38 and SAPK2b/p38 beta 2 but not other mitogen-activated protein kinase family members. Like inhibitors of other protein kinases, SB 203580 binds in the ATP-binding pocket of SAPK2a/p38.


RESULTS
The SAP kinases SAPK1 gamma/JNK1, SAPK3 and SAPK4 are not inhibited by SB 203580, because they have methionine in the position equivalent to Thr106 in the ATP-binding region of SAPK2a/p38 and SAPK2b/p38 beta 2. Using site-directed mutagenesis of five SAP kinases and the type I and type II TGF beta receptors, we have established that for a protein kinase to be inhibited by SB 203580, the sidechain of this residue must be no larger than that of threonine. Sensitivity to inhibition by SB 203580 is greatly enhanced when the sidechain is even smaller, as in serine, alanine or glycine. Thus, the type I TGF beta receptor, which has serine at the position equivalent to Thr106 of SAPK2a/p38 and SAPK2b/p38 beta 2, is inhibited by SB 203580.


CONCLUSIONS
These findings explain how drugs that target the ATP-binding site can inhibit protein kinases specifically, and show that the presence of threonine or a smaller amino acid at the position equivalent to Thr106 of SAPK2a/p38 and SAPK2b/p38 beta 2 is diagnostic of whether a protein kinase is sensitive to the pyridinyl imidazole class of inhibitor.
Eyers
P A
PA
Department of Biochemistry, University of Dundee, UK.
Craxton
M
M
Morrice
N
N
Cohen
P
P
Goedert
M
M
D030201:Activin Receptors, Type I; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology*; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000037:antagonists & inhibitors / Q000235:genetics; D048291:Mitogen-Activated Protein Kinase 12; D048292:Mitogen-Activated Protein Kinase 13; D020928:Mitogen-Activated Protein Kinases; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D011725:Pyridines / Q000494:pharmacology*; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000037:antagonists & inhibitors; D013329:Structure-Activity Relationship; D016212:Transforming Growth Factor beta / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases
D004791:Enzyme Inhibitors; D007093:Imidazoles; D047428:Protein Kinase Inhibitors; D011725:Pyridines; D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta; D011494:Protein Kinases; D048291:Mitogen-Activated Protein Kinase 12; D048292:Mitogen-Activated Protein Kinase 13; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D017346:Protein Serine-Threonine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D030201:Activin Receptors, Type I; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II; C093642:SB 203580