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Issue 40, 2020
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Local dynamics of the photo-switchable protein PYP in ground and signalling state probed by 2D-IR spectroscopy of –SCN labels

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Abstract

Incorporation of minimally perturbative vibrational probes into proteins allows combination of the femtosecond time resolution of two dimensional infrared (2D-IR) spectroscopy with a spatial resolution on the level of single side chains. Here, we apply the thiocyanate (–SCN) label introduced by the cyanylation of cysteine to probe local dynamics in the photo-switchable protein PYP. We incorporated the –SCN label into five positions of the protein structure including PYP's core region, its solvent exposed surface and the chromophore-binding pocket. The analysis of –SCN's time dependent 2D-IR lineshape provides insight into the timescales and amplitudes of the dynamics in the label's protein and solvent microenvironment. We present a detailed analysis of the local protein dynamics found at all five labelling positions in PYP's dark state (pG). Absorption of a blue photon triggers the isomerisation of PYP's chromophore and eventually leads to an overall reorganisation of the protein structure, where PYP ends up in a less structured signalling state pB. Employing 2D-IR spectroscopy also on the signalling state allows assessment of the change of local dynamics compared to the pG state.

Graphical abstract: Local dynamics of the photo-switchable protein PYP in ground and signalling state probed by 2D-IR spectroscopy of –SCN labels

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Article information


Submitted
13 Aug 2020
Accepted
29 Sep 2020
First published
29 Sep 2020

Phys. Chem. Chem. Phys., 2020,22, 22963-22972
Article type
Paper

Local dynamics of the photo-switchable protein PYP in ground and signalling state probed by 2D-IR spectroscopy of –SCN labels

J. M. Schmidt-Engler, L. Blankenburg, R. Zangl, J. Hoffmann, N. Morgner and J. Bredenbeck, Phys. Chem. Chem. Phys., 2020, 22, 22963
DOI: 10.1039/D0CP04307A

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