Molecular and Cellular Biochemistry

, Volume 367, Issue 1, pp 125–140

A shift in the salt bridge interaction of residues D620 and E621 mediates the constitutive activation of Jak2-H538Q/K539L

  • Kavitha Gnanasambandan
  • Andrew T. Magis
  • Peter P. Sayeski
Article

DOI: 10.1007/s11010-012-1326-7

Cite this article as:
Gnanasambandan, K., Magis, A.T. & Sayeski, P.P. Mol Cell Biochem (2012) 367: 125. doi:10.1007/s11010-012-1326-7

Abstract

Jak2 mutations in the exon 14 and exon 12 regions that cause constitutive activation have been associated with myeloproliferative neoplasms. We have previously shown that a pi stacking interaction between F617 and F595 is important for the constitutive activation of Jak2-V617F (Gnanasambandan et al., Biochemistry 49:9972–9984, 2010). Here, using a combination of molecular dynamics (MD) simulations and in vitro mutagenesis, we studied the molecular mechanism for the constitutive activation of the Jak2 exon 12 mutation, H538Q/K539L. The activation levels of Jak2-H538Q/K539L were found to be similar to that of Jak2-V617F, and Jak2-H538Q/K539L/V617F. Data from MD simulations indicated a shift in the salt bridge interactions of D620 and E621 with K539 in Jak2-WT to R541 in Jak2-H538Q/K539L. When compared to Jak2-WT, K539A mutation resulted in increased activation, while K539D or K539E mutations diminished Jak2 activation by 50 %. In the context of Jak2-H538Q/K539L, R541A mutation reduced its activation by 50 %, while R541D and R541E mutations returned its activation levels to that of Jak2-WT. Collectively, these results indicate that a shift in the salt bridge interaction of D620 and E621 with K539 in Jak2-WT to R541 in Jak2-H538Q/K539L is critical for constitutive activation of this Jak2 exon 12 mutant.

Keywords

Jak2Exon 12 mutationMPNsSalt bridgeSimulationsMechanism

Abbreviations

Jak

Janus kinase

STAT

Signal transducers and activators of transcription

FERM

4.1 protein/ezrin/radixin/moesin

MPN

Myeloproliferative neoplasms

SH2

Src homology 2

Supplementary material

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Interactions at the JH1-JH2 interface in Jak2-WT Supplementary material 1 (MPG 31.1 mb)

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Interactions at the JH1-JH2 interface in Jak2-H538Q/K539L Supplementary material 2 (MPG 30.8 mb)

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Interactions at the JH1-JH2 interface in Jak2-V617F Supplementary material 3 (MPG 31.7 mb)

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Interactions at the JH1-JH2 interface in Jak2-H538Q/K539L/V617F Supplementary material 4 (MPG 32.3 mb)

Copyright information

© Springer Science+Business Media, LLC. 2012

Authors and Affiliations

  • Kavitha Gnanasambandan
    • 1
  • Andrew T. Magis
    • 2
  • Peter P. Sayeski
    • 1
  1. 1.Department of Physiology and Functional GenomicsUniversity of Florida College of MedicineGainesvilleUSA
  2. 2.Center for Biophysics and Computational BiologyUniversity of IllinoisUrbana-ChampaignUSA