Phycobilisomes Harbor FNR<sub>L</sub> in Cyanobacteria

ABSTRACT Cyanobacterial phycobilisomes (PBSs) are photosynthetic antenna complexes that harvest light energy and supply it to two reaction centers (RCs) where photochemistry starts. PBSs can be classified into two types, depending on the presence of allophycocyanin (APC): CpcG-PBS and CpcL-PBS. Beca...

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Autores principales:	Haijun Liu, Daniel A. Weisz, Mengru M. Zhang, Ming Cheng, Bojie Zhang, Hao Zhang, Gary S. Gerstenecker, Himadri B. Pakrasi, Michael L. Gross, Robert E. Blankenship
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2019
Materias:	CpcL-PBS isotopic cross-linking photosynthesis mass spectrometry Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/e8504fc5146e4a51869590a6feaf6899
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spelling	oai:doaj.org-article:e8504fc5146e4a51869590a6feaf68992021-11-15T15:55:24ZPhycobilisomes Harbor FNR<sub>L</sub> in Cyanobacteria10.1128/mBio.00669-192150-7511https://doaj.org/article/e8504fc5146e4a51869590a6feaf68992019-04-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.00669-19https://doaj.org/toc/2150-7511ABSTRACT Cyanobacterial phycobilisomes (PBSs) are photosynthetic antenna complexes that harvest light energy and supply it to two reaction centers (RCs) where photochemistry starts. PBSs can be classified into two types, depending on the presence of allophycocyanin (APC): CpcG-PBS and CpcL-PBS. Because the accurate protein composition of CpcL-PBS remains unclear, we describe here its isolation and characterization from the cyanobacterium Synechocystis sp. strain 6803. We found that ferredoxin-NADP+ oxidoreductase (or FNRL), an enzyme involved in both cyclic electron transport and the terminal step of the electron transport chain in oxygenic photosynthesis, is tightly associated with CpcL-PBS as well as with CpcG-PBS. Room temperature and low-temperature fluorescence analyses show a red-shifted emission at 669 nm in CpcL-PBS as a terminal energy emitter without APC. SDS-PAGE and quantitative mass spectrometry reveal an increased content of FNRL and CpcC2, a rod linker protein, in CpcL-PBS compared to that of CpcG-PBS rods, indicative of an elongated CpcL-PBS rod length and its potential functional differences from CpcG-PBS. Furthermore, we combined isotope-encoded cross-linking mass spectrometry with computational protein structure predictions and structural modeling to produce an FNRL-PBS binding model that is supported by two cross-links between K69 of FNRL and the N terminus of CpcB, one component in PBS, in both CpcG-PBS and CpcL-PBS (cross-link 1), and between the N termini of FNRL and CpcB (cross-link 2). Our data provide a novel functional assembly form of phycobiliproteins and a molecular-level description of the close association of FNRL with phycocyanin in both CpcG-PBS and CpcL-PBS. IMPORTANCE Cyanobacterial light-harvesting complex PBSs are essential for photochemistry in light reactions and for balancing energy flow to carbon fixation in the form of ATP and NADPH. We isolated a new type of PBS without an allophycocyanin core (i.e., CpcL-PBS). CpcL-PBS contains both a spectral red-shifted chromophore, enabling efficient energy transfer to chlorophyll molecules in the reaction centers, and an increased FNRL content with various rod lengths. Identification of a close association of FNRL with both CpcG-PBS and CpcL-PBS brings new insight to its regulatory role for fine-tuning light energy transfer and carbon fixation through both noncyclic and cyclic electron transport.Haijun LiuDaniel A. WeiszMengru M. ZhangMing ChengBojie ZhangHao ZhangGary S. GersteneckerHimadri B. PakrasiMichael L. GrossRobert E. BlankenshipAmerican Society for MicrobiologyarticleCpcL-PBSisotopic cross-linkingphotosynthesismass spectrometryMicrobiologyQR1-502ENmBio, Vol 10, Iss 2 (2019)
institution	DOAJ
collection	DOAJ
language	EN
topic	CpcL-PBS isotopic cross-linking photosynthesis mass spectrometry Microbiology QR1-502
spellingShingle	CpcL-PBS isotopic cross-linking photosynthesis mass spectrometry Microbiology QR1-502 Haijun Liu Daniel A. Weisz Mengru M. Zhang Ming Cheng Bojie Zhang Hao Zhang Gary S. Gerstenecker Himadri B. Pakrasi Michael L. Gross Robert E. Blankenship Phycobilisomes Harbor FNR<sub>L</sub> in Cyanobacteria
description	ABSTRACT Cyanobacterial phycobilisomes (PBSs) are photosynthetic antenna complexes that harvest light energy and supply it to two reaction centers (RCs) where photochemistry starts. PBSs can be classified into two types, depending on the presence of allophycocyanin (APC): CpcG-PBS and CpcL-PBS. Because the accurate protein composition of CpcL-PBS remains unclear, we describe here its isolation and characterization from the cyanobacterium Synechocystis sp. strain 6803. We found that ferredoxin-NADP+ oxidoreductase (or FNRL), an enzyme involved in both cyclic electron transport and the terminal step of the electron transport chain in oxygenic photosynthesis, is tightly associated with CpcL-PBS as well as with CpcG-PBS. Room temperature and low-temperature fluorescence analyses show a red-shifted emission at 669 nm in CpcL-PBS as a terminal energy emitter without APC. SDS-PAGE and quantitative mass spectrometry reveal an increased content of FNRL and CpcC2, a rod linker protein, in CpcL-PBS compared to that of CpcG-PBS rods, indicative of an elongated CpcL-PBS rod length and its potential functional differences from CpcG-PBS. Furthermore, we combined isotope-encoded cross-linking mass spectrometry with computational protein structure predictions and structural modeling to produce an FNRL-PBS binding model that is supported by two cross-links between K69 of FNRL and the N terminus of CpcB, one component in PBS, in both CpcG-PBS and CpcL-PBS (cross-link 1), and between the N termini of FNRL and CpcB (cross-link 2). Our data provide a novel functional assembly form of phycobiliproteins and a molecular-level description of the close association of FNRL with phycocyanin in both CpcG-PBS and CpcL-PBS. IMPORTANCE Cyanobacterial light-harvesting complex PBSs are essential for photochemistry in light reactions and for balancing energy flow to carbon fixation in the form of ATP and NADPH. We isolated a new type of PBS without an allophycocyanin core (i.e., CpcL-PBS). CpcL-PBS contains both a spectral red-shifted chromophore, enabling efficient energy transfer to chlorophyll molecules in the reaction centers, and an increased FNRL content with various rod lengths. Identification of a close association of FNRL with both CpcG-PBS and CpcL-PBS brings new insight to its regulatory role for fine-tuning light energy transfer and carbon fixation through both noncyclic and cyclic electron transport.
format	article
author	Haijun Liu Daniel A. Weisz Mengru M. Zhang Ming Cheng Bojie Zhang Hao Zhang Gary S. Gerstenecker Himadri B. Pakrasi Michael L. Gross Robert E. Blankenship
author_facet	Haijun Liu Daniel A. Weisz Mengru M. Zhang Ming Cheng Bojie Zhang Hao Zhang Gary S. Gerstenecker Himadri B. Pakrasi Michael L. Gross Robert E. Blankenship
author_sort	Haijun Liu
title	Phycobilisomes Harbor FNR<sub>L</sub> in Cyanobacteria
title_short	Phycobilisomes Harbor FNR<sub>L</sub> in Cyanobacteria
title_full	Phycobilisomes Harbor FNR<sub>L</sub> in Cyanobacteria
title_fullStr	Phycobilisomes Harbor FNR<sub>L</sub> in Cyanobacteria
title_full_unstemmed	Phycobilisomes Harbor FNR<sub>L</sub> in Cyanobacteria
title_sort	phycobilisomes harbor fnr<sub>l</sub> in cyanobacteria
publisher	American Society for Microbiology
publishDate	2019
url	https://doaj.org/article/e8504fc5146e4a51869590a6feaf6899
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Phycobilisomes Harbor FNR<sub>L</sub> in Cyanobacteria

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