Dariusz Niedzwiedzki, Rupal Singh Tomar, Fatima Akram, Anna M Williams, Haijun Liu
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引用次数: 0
Abstract
Phycobilisome (PBS) is a pigment-protein complex utilized by red algae and cyanobacteria in photosynthesis for light harvesting. A cyanobacterium Synechocystis sp. PCC 6803 contains PBS with a tricylindrical core built of allophycocyanin (APC) disks where six phycocyanin (PC) rods are attached. The top core cylinder is seemingly involved in attaching four PC rods and binding orange carotenoid protein (OCP) to quench excess of excitation energy. In this study, we have deleted the third linker domain (LD3) of ApcE subunit of PBS which assembles four APC discs into the top core cylinder. The mutation resulted in PBS with bicylindrical core, structurally comparable to the naturally existing PBS from Synechococcus 7942. Lack of LD3 and the top APC cylinder reduces the excitation energy transfer between PC and APC in the mutant. Moreover, these PBSs are more prone to light induced-photodamage and do not bind to the photoactivated orange carotenoid protein (OCP), a known PBS excitation quencher. These findings highlight the complex and elegant interplay between PBS architecture and functional efficiency, suggesting that in PBSs with naturally tri-cylindrical cores, the top cylinder has essential roles in recruiting the rods and proper binding of OCP and recruitment of the four PC rods.
期刊介绍:
ChemPhysChem is one of the leading chemistry/physics interdisciplinary journals (ISI Impact Factor 2018: 3.077) for physical chemistry and chemical physics. It is published on behalf of Chemistry Europe, an association of 16 European chemical societies.
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