Conformational Dynamics and Multimerization of Active Forms of the EphrinB Receptor 2 Kinase Domain

• Active and autoinhibited forms of the ephrinB receptor 2 (EphB2) kinase domain have been studied using NMR spectroscopy. The project was initiated because of the finding that the crystal structures of active forms of the kinase domain and previous NMR studies suggested that a change in inter-lobe flexibility and the sampling of catalytically competent excited states conformations are responsible for activity. Using Carr-Purcell-Meiboom-Gill relaxation dispersion experiments, we have measured millisecond dynamics to identify such states. We have also performed concentration dependent relaxation experiments and analytical ultracentrifugation experiments that report on the effective protein size to look for possible differences in self-association for active and autoinhibited forms of the EphB2 kinase domain. We show that the active but not autoinhibited forms exchange between a ground state and an excited state at a rate of 1900 s-1. Similar results were found for the S677/680A mutant of the protein. The nature and importance of the excited state is still unknown. Our most important finding is that active forms of the kinase domain self-associate in a concentration dependent manner and form tetramers and possibly larger oligomers. Multimerization of the kinase domain may enable the assembly of complexes of downstream proteins and could be important for Eph signaling.

Ämnesord

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

Nyckelord

Kinase activation | Eph receptors | chemical exchange | nmr spectroscopy | protein dynamics | self-association

Publikations- och innehållstyp

vet (ämneskategori)

ovr (ämneskategori)