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

Publication date: Available online 14 November 2019Source: Biochimica et Biophysica Acta (BBA) - BioenergeticsAuthor(s): 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 PolívkaAbstractThe 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. Howeve...

Source: Biochimica et Biophysica Acta (BBA) Bioenergetics - November 15, 2019 Category: Biochemistry Source Type: research