Abstract
The mitogen-activation protein kinase ERK2 is tightly regulated by multiple phosphatases, including those of the kinase interaction motif (KIM) PTP family (STEP, PTPSL and HePTP). Here, we use small angle X-ray scattering (SAXS) and isothermal titration calorimetry (ITC) to show that the ERK2:STEP complex is compact and that residues outside the canonical KIM motif of STEP contribute to ERK2 binding. Furthermore, we analyzed the interaction of PTPSL with ERK2 showing that residues outside of the canonical KIM motif also contribute to ERK2 binding. The integration of this work with previous studies provides a quantitative and structural map of how the members of a single family of regulators, the KIM-PTPs, differentially interact with their corresponding MAPKs, ERK2 and p38α.
Highlights
The mitogen-activation protein kinases (MAPKs; ERK, p38 and JNK) are cytosolic serine/threonine-specific kinases that coordinate the cellular response to a range of extracellular stimuli
To better understand the molecular determinants that allow regulatory proteins to discriminate between ERK2 and p38a, we investigated the interaction of PTPSL and STEP with ERK2 and compared them with our previous study examining the same interactions with p38a
We recently showed that the ERK2:HePTP resting-state complex is highly extended in solution with a radius of gyration (Rg) of 33.3 Aand a maximum dimension (Dmax) of 110 A [16]
Summary
The mitogen-activation protein kinases (MAPKs; ERK, p38 and JNK) are cytosolic serine/threonine-specific kinases that coordinate the cellular response to a range of extracellular stimuli. While a plethora of cell biological data is available, much less systematic interaction data using quantitative methods, such as isothermal titration calorimetry (ITC), has been reported This is of special interest, as recent studies have shown that while KIMpeptides derived from KIM-containing regulatory proteins and substrates readily discriminate between ERK2/p38 and JNK, they discriminate poorly between ERK2 and p38 [7]. We find that within the family both STEP and PTPSL interact with ERK2 and p38a more strongly than does HePTP To determine if this discrimination between p38 and ERK2 is specific for this regulatory protein family, we compared the interaction of a MAP Kinase Phosphatase (MKP; DUSP16) MAPK binding domain with p38a [18] and ERK2. Our data is providing a coherent understanding of how subtle differences between the KIM-PTPs contribute to MAPK selectivity and, in turn, MAPK signal fidelity
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