Showing papers on "Phycoerythrobilin published in 2017"

Adaptation to Blue Light in Marine Synechococcus Requires MpeU, an Enzyme with Similarity to Phycoerythrobilin Lyase Isomerases.

Abstract: Marine Synechococcus cyanobacteria have successfully adapted to environments with different light colors, which likely contributes to this genus being the second most abundant photosynthetic microorganism worldwide. Populations of Synechococcus that grow in deep, blue ocean waters contain large amounts of the blue-light absorbing chromophore phycourobilin (PUB) in their light harvesting complexes (phycobilisomes). Here we show that all Synechococcus strains adapted to blue light possess a gene called mpeU. MpeU is structurally similar to phycobilin lyases, enzymes that ligate chromophores to phycobiliproteins. Interruption of mpeU caused a reduction in PUB content, produced impaired phycobilisomes and reduced growth rate more strongly in blue than green light. When mpeU was reintroduced in the mpeU mutant background, the mpeU-less phenotype was complemented in terms of PUB content and phycobilisome content. Fluorescence spectra of mpeU mutant cells and purified phycobilisomes revealed red-shifted phycoerythrin emission peaks, likely indicating a defect in chromophore ligation to phycoerythrin-I (PE-I) or phycoerythrin-II (PE-II). Our results suggest that MpeU is a lyase-isomerase that attaches a phycoerythrobilin to a PEI or PEII subunit and isomerizes it to PUB. MpeU is therefore an important determinant in adaptation of Synechococcus spp. to capture photons in blue light environments throughout the world’s oceans.

Biosynthesis of Cyanobacterial Light-Harvesting Pigments and Their Assembly into Phycobiliproteins

Abstract: Cyanobacteria are a group of bacteria, which are able to perfom oxygenic photosynthesis (rely on oxygenic photosynthesis as a main energy source) to convert sun light into chemical energy. In addition to the photosystems, cyanobacteria employ phycobilisomes to enhance their light-harvesting abilities. Phycobilisomes consist of phycobiliproteins (mainly phycocyanin and phycoerythrin) with covalently attached open-chain tetrapyrroles (phycobilins) as light-harvesting pigments. These phycobilins are derived from heme. The first step of bilin synthesis is the ring opening reaction of heme into biliverdin IXα mediated by heme oxygenases. A set of different ferredoxin-dependent bilin reductases catalyse the reactions from biliverdin IXα to several phycobilins. These pigments are subsequently attached to conserved cysteine residues in the phycobiliproteins. In order to ensure the correct attachment of the phycobilins and the chromophore composition of the phycobiliproteins, the binding is mediated by phycobiliprotein-lyases. Recent studies showed that this machinery is not only present in cyanobacteria but also in phages which infect cyanobacteria. This chapter describes the biosynthesis and assembly of all components of functional phycobilisomes and their role in energy conversion as well as adaptations to changing environmental conditions.

Preparation method of high fluorescence intensity recombinant phycobiliprotein concatermer

Abstract: The present invention belongs to the field of fluorescent proteins in biotechnology, and particularly relates to a preparation method of a high fluorescence intensity recombinant phycobiliprotein concatermer. According to the preparation method, a streptavidin gene is linked to an allophycocyanin alpha subunit gene through a linker sequence; on the basis, one or a plurality of allophycocyanin alpha subunit genes are connected in series through linker sequences to form a fusion gene; and the fusion gene, a phycobiliprotein lyase gent and a phycoerythrobilin biosynthetic enzyme gene co-express in Escherichia coli to obtain the recombinant allophycocyanin concatermer with characteristics of biotin binding ability and high fluorescence intensity. According to the present invention, tn the immunofluorescence assay, the recombinant phycobiliprotein concatermer can achieve the strong fluorescent signal compared to the recombinant phycobiliprotein monomer; and the prepared recombinant phycobiliprotein concatermer can be adopted as the fluorescent marker for immunofluorescence detection in the field of biology and biomedicine.

Repurposing a photosynthetic antenna protein as a super-resolution microscopy label

Abstract: Techniques such as Stochastic Optical Reconstruction Microscopy (STORM) and Structured Illumination Microscopy (SIM) have increased the achievable resolution of optical imaging, but few fluorescent proteins are suitable for super-resolution microscopy, particularly in the far-red and near-infrared emission range. Here we demonstrate the applicability of CpcA, a subunit of the photosynthetic antenna complex in cyanobacteria, for STORM and SIM imaging. The periodicity and width of fabricated nanoarrays of CpcA, with a covalently attached phycoerythrobilin (PEB) or phycocyanobilin (PCB) chromophore, matched the lines in reconstructed STORM images. SIM and STORM reconstructions of Escherichia coli cells harbouring CpcA-labelled cytochrome bd 1 ubiquinol oxidase in the cytoplasmic membrane show that CpcA-PEB and CpcA-PCB are suitable for super-resolution imaging in vivo. The stability, ease of production, small size and brightness of CpcA-PEB and CpcA-PCB demonstrate the potential of this largely unexplored protein family as novel probes for super-resolution microscopy.

Gene Manipulation and Biosynthesis of Phycobiliproteins

Abstract: The phycobiliproteins (PBPs) are a family of accessory light-harvesting protein complexes found in cyanobacteria, red algae, and cryptomonads. They are associated with noncyclic linear/open-chain tetrapyrrole prosthetic groups that consist of four pyrrole rings (A, B, C, and D) integrated in α, β, and γ biliproteins. Commonly, PBPs are associated with αβ heterodimers in which each subunit carries bilin(s) thioether-linked to particular cysteinyl residues.On the basis of chromophore structure, there are four kinds of phycobilins found in cyanobacteria: phycoerythrobilin (PEB), phycocyanobilin (PCB), phycourobilin (PUB), and phycoviolobilin (PVB). Moreover, nonpigmented linker polypeptides are embedded in the structure which are responsible for stabilization and modulation of energy absorption within PBPs and help in effective energy transfers toward the photosystem. Much progress has been made about understanding the biosynthesis mechanism of PBPs. However, there is still limitation to utilize the biosynthetic pathway of PBPs for more production to fulfill demand of the global economy. This chapter provides the details on studies about the mechanism of biosynthesis of PBPs and probable involvement of genes and enzymes which act as precursors.

Method for preparing recombinant phycobiliprotein concatemer having high fluorescence intensity

Abstract: Provided is a method for preparing a recombinant phycobiliprotein concatemer having high fluorescence intensity. A streptavidin gene is connected to an allophycocyanin α-subunit gene, and then one or more allophycocyanin α-subunit genes are connected. The obtained fusion gene is co-expressed with a phycobiliprotein lyase gene and a phycoerythrobilin biosynthetic enzyme gene in Escherichia coli, so as to obtain a recombinant phycobiliprotein concatemer having biotin binding ability and high fluorescence intensity, which can be used as a marker for immunofluorescence detection.