X-ray Scattering Studies of Methylophilus methylotrophus (sp. W3A1) Electron-transferring Flavoprotein: EVIDENCE FOR MULTIPLE CONFORMATIONAL STATES AND AN INDUCED FIT MECHANISM FOR ASSEMBLY WITH TRIMETHYLAMINE DEHYDROGENASE

Matthew Jones,Jaswir Basran,Michael J Sutcliffe,J.Günter Grossmann,Nigel S Scrutton

doi:10.1074/jbc.m001564200

Matthew Jones, Jaswir Basran + Show 3 more

Open Access

https://doi.org/10.1074/jbc.m001564200

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Abstract

Small angle x-ray solution scattering has been used to generate a low resolution, model-independent molecular envelope structure for electron-transferring flavoprotein (ETF) from Methylophilus methylotrophus (sp. W(3)A(1)). Analysis of both the oxidized and 1-electron-reduced (anionic flavin semiquinone) forms of the protein revealed that the solution structures of the protein are similar in both oxidation states. Comparison of the molecular envelope of ETF from the x-ray scattering data with previously determined structural models of the protein suggests that ETF samples a range of conformations in solution. These conformations correspond to a rotation of domain II with respect to domains I and III about two flexible "hinge" sequences that are unique to M. methylotrophus ETF. The x-ray scattering data are consistent with previous models concerning the interaction of M. methylotrophus ETF with its physiological redox partner, trimethylamine dehydrogenase. Our data reveal that an "induced fit" mechanism accounts for the assembly of the trimethylamine dehydrogenase-ETF electron transfer complex, consistent with spectroscopic and modeling studies of the assembly process.

Highlights

Small angle x-ray solution scattering has been used to generate a low resolution, model-independent molecular envelope structure for electron-transferring flavoprotein (ETF) from Methylophilus methylotrophus
It was initially thought that the oxidation state of M. methylotrophus ETF may play a role in the predisposition of the protein to be in either the electron transfer (eT)-active or the eT-inactive conformation and that the redox state of the protein would act as a switch between the different conformational states
The fitted experimental small angle x-ray scattering (SAXS) profile for M. methylotrophus ETF closely resembled the simulated profile for the eT-active rather than the eT-inactive conformation of ETF, initially leading us to believe that the conformation of M. methylotrophus ETF in solution resembles that of the postulated eT-active form

Summary

Introduction

Small angle x-ray solution scattering has been used to generate a low resolution, model-independent molecular envelope structure for electron-transferring flavoprotein (ETF) from Methylophilus methylotrophus Comparison of the molecular envelope of ETF from the x-ray scattering data with previously determined structural models of the protein suggests that ETF samples a range of conformations in solution.

Results

Conclusion