title: Characterization and responses to environmental cues of a photosynthetic antenna-deficient mutant of the filamentous cyanobacterium Anabaena sp. PCC 7120.
abstract: The cyanobacterial phycobilisome (PBS) is a giant pigment-protein complex which harvests light energy for photosynthesis and comprises two structures: a core and peripheral rods. Most studies on PBS structure and function are based on mutants of unicellular strains. In this report, we describe the phenotypic and genetic characterization of a transposon mutant of the filamentous Anabaena sp. strain PCC 7120, denoted LC1, which cannot synthesize the phycobiliprotein phycocyanin (PC), the main component of the rods; in this mutant, the transposon had inserted into the cpcB gene (orf alr0528) which putatively encodes PC-β chain. Mutant LC1 was able to synthesize phycoerythrocyanin (PEC), a phycobiliprotein (PBP) located at the terminal region of the rods; but in the absence of PC, PEC did not attach to the PBSs that only retained the allophycocyanin (APC) core; ferredoxin: NADP+-oxidoreductase (FNR) that is associated with the PBS in the wild type, was not found in isolated PBSs from LC1. The performance of the mutant exposed to different environmental conditions was evaluated. The mutant phenotype was successfully complemented by cloning and transfer of the wild type complete cpc operon to mutant LC1. Interestingly, LC1 compensated its mutation by significantly increasing the number of its core-PBS and the effective quantum yield of photosystem II (PSII) photochemistry; this feature suggests a more efficient energy conversion in the mutant which may be useful for biotechnological applications.
authors.affiliation: Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid 28049, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Leganés
authors.affiliation: Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid 28049, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Martínez-Granero
authors.affiliation: Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid 28049, Spain.
authors.forename: M Ángeles
authors.initials: MÁ
authors.lastname: Muñoz-Martín
authors.affiliation: Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid 28049, Spain.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Marco
authors.affiliation: Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid 28049, Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: Jorge
authors.affiliation: Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid 28049, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Carvajal
authors.affiliation: Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid 28049, Spain.
authors.forename: Teresa
authors.initials: T
authors.lastname: Vida
authors.affiliation: Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid 28049, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: González-Pleiter
authors.affiliation: Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid 28049, Spain. Electronic address: francisca.pina@uam.es.
authors.forename: Francisca
authors.initials: F
authors.lastname: Fernández-Piñas
mesh_terms: D017033:Anabaena / Q000378:metabolism* / Q000502:physiology; D001426:Bacterial Proteins / Q000378:metabolism; D005288:Ferredoxins / Q000378:metabolism; D010788:Photosynthesis / Q000502:physiology; D052980:Phycobilins / Q000378:metabolism; D045524:Phycobilisomes / Q000378:metabolism; D010798:Phycocyanin / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D005288:Ferredoxins; D052980:Phycobilins; D045524:Phycobilisomes; C002497:allophycocyanin; C038397:phycoerythrocyanin; D010798:Phycocyanin
keywords: Anabaena; Cpc genes; Photosynthesis; Phycobilisome; Phycocyanin-less mutant