Comparative ultrafast spectroscopy and structural analysis of OCP1 and OCP2 from Tolypothrix

Valentyna Kuznetsova; Maria Agustina Dominguez-Martin; Han Bao; Sayan Gupta; Markus Sutter; Miroslav Kloz; Mateusz Rebarz; Martin Přeček; Yan Chen; Christopher J Petzold; Corie Y Ralston; Cheryl A Kerfeld; Tomáš Polívka

doi:10.1016/j.bbabio.2019.148120

Comparative ultrafast spectroscopy and structural analysis of OCP1 and OCP2 from Tolypothrix

Biochim Biophys Acta Bioenerg. 2020 Feb 1;1861(2):148120. doi: 10.1016/j.bbabio.2019.148120. Epub 2019 Nov 14.

Authors

Affiliations

¹ Institute of Physics, Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05 České Budějovice, Czech Republic.
² MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI 48824, USA.
³ Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
⁴ MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI 48824, USA; Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
⁵ ELI Beamlines, Institute of Physics, Czech Academy of Sciences, Za Radnicí 835, 252 41 Dolní Břežany, Czech Republic.
⁶ Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
⁷ MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI 48824, USA; Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA.
⁸ Institute of Physics, Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05 České Budějovice, Czech Republic. Electronic address: tpolivka@jcu.cz.

Abstract

The orange carotenoid protein (OCP) is a structurally and functionally modular photoactive protein involved in cyanobacterial photoprotection. Recently, based on bioinformatic analysis and phylogenetic relationships, new families of OCP have been described, OCP2 and OCPx. The first characterization of the OCP2 showed both faster photoconversion and back-conversion, and lower fluorescence quenching of phycobilisomes relative to the well-characterized OCP1. Moreover, OCP2 is not regulated by the fluorescence recovery protein (FRP). In this work, we present a comprehensive study combining ultrafast spectroscopy and structural analysis to compare the photoactivation mechanisms of OCP1 and OCP2 from Tolypothrix PCC 7601. We show that despite significant differences in their functional characteristics, the spectroscopic properties of OCP1 and OCP2 are comparable. This indicates that the OCP functionality is not directly related to the spectroscopic properties of the bound carotenoid. In addition, the structural analysis by X-ray footprinting reveals that, overall, OCP1 and OCP2 have grossly the same photoactivation mechanism. However, the OCP2 is less reactive to radiolytic labeling, suggesting that the protein is less flexible than OCP1. This observation could explain fast photoconversion of OCP2.

Keywords: OCP1; OCP2; Photoactivation; Ultrafast spectroscopy; X-ray footprinting.

Publication types

Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Bacterial Proteins / chemistry*
Cyanobacteria / chemistry*
Phycobilisomes / chemistry*
Spectrometry, Fluorescence

Substances

Bacterial Proteins
Phycobilisomes

Grants and funding

R01 GM126218/GM/NIGMS NIH HHS/United States