Two-step structural changes in orange carotenoid protein photoactivation revealed by time-resolved Fourier transform infrared spectroscopy

dc.contributor.authorMezzetti, Alberto
dc.contributor.authorAlexandre, Maxime
dc.contributor.authorThurotte, Adrien
dc.contributor.authorWilson, Adjele
dc.contributor.authorGwizdala, Michal
dc.contributor.authorKirilovsky, Diana
dc.date.accessioned2019-07-22T09:52:17Z
dc.date.issued2019-03
dc.descriptionSupporting Information : Static FTIR difference spectra after illumination at different temperatures and time-resolved FTIR difference spectra under illumination at 298 K.en_ZA
dc.description.abstractThe orange carotenoid protein (OCP), which is essential in cyanobacterial photoprotection, is the first photoactive protein containing a carotenoid as an active chromophore. Static and time-resolved Fourier transform infrared (FTIR) difference spectroscopy under continuous illumination at different temperatures was applied to investigate its photoactivation mechanism. Here, we demonstrate that in the OCP, the photo-induced conformational change involves at least two different steps, both in the second timescale at 277 K. Each step involves partial reorganization of α-helix domains. At early illumination times, the disappearance of a nonsolvent-exposed α-helix (negative 1651 cm–1 band) is observed. At longer times, a 1644 cm–1 negative band starts to bleach, showing the disappearance of a solvent-exposed α-helix, either the N-terminal extension and/or the C-terminal tail. A kinetic analysis clearly shows that these two events are asynchronous. Minor modifications in the overall FTIR difference spectra confirm that the global protein conformational change consists of—at least—two asynchronous contributions. Comparison of spectra recorded in H2O and D2O suggests that internal water molecules may contribute to the photoactivation mechanism.en_ZA
dc.description.departmentPhysicsen_ZA
dc.description.embargo2020-03-21
dc.description.librarianhj2019en_ZA
dc.description.sponsorshipGrants from the Agence Nationale de la Recherche (ANR projects CYANOPROTECT (ANR-11-BSV8-0003) and RECYFUEL (ANR-16-CE05-0026)). The research was also supported by the Centre National de la Recherche Scientifique (CNRS) and the Commissariat à l’Energie Atomique (CEA). The salary of A.T. was financed by Paris-Saclay University (IDI project grant no. ANR-11-IDEX-0003-02). The salary of M.G. was financed by HARVEST EU FP7 Marie Curie Research Training Network. M.G. acknowledges the funding from European Molecular Biology Organization (EMBO) via Long-Term Fellowship, from Claude Leon Foundation and from the University of Pretoria. This work was supported by the French Infrastructure for Integrated Structural Biology (FRISBI) ANR-10-INSB-05-01.en_ZA
dc.description.urihttp://pubs.acs.org/journal/jpcbfken_ZA
dc.identifier.citationMezzetti, A., Alexandre, M., Thurotte, A., et al. 2019, 'Two-step structural changes in orange carotenoid protein photoactivation revealed by time-resolved Fourier transform infrared spectroscopy', Journal of Physical Chemistry B, vol. 123, no. 15, pp. 3259-3566.en_ZA
dc.identifier.issn1520-6106 (print)
dc.identifier.issn1520-5207 (online)
dc.identifier.other10.1021/acs.jpcb.9b01242
dc.identifier.urihttp://hdl.handle.net/2263/70772
dc.language.isoenen_ZA
dc.publisherAmerican Chemical Societyen_ZA
dc.rightsThis document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of Physical Chemistry B, © 2019 American Chemical Society after peer review and technical editing by the publisher.en_ZA
dc.subjectOrange carotenoid protein (OCP)en_ZA
dc.subjectPhotoactive proteinen_ZA
dc.subjectFourier transform infrared spectroscopy (FTIR)en_ZA
dc.titleTwo-step structural changes in orange carotenoid protein photoactivation revealed by time-resolved Fourier transform infrared spectroscopyen_ZA
dc.typePostprint Articleen_ZA

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