Structural and functional dynamics of tyrosine amino acid in phycocyanin of hot-spring cyanobacteria: A possible pathway for internal energy transfer

Kannaujiya, Vinod K.; Rahman, Akhlaqur; Adinath,; Sundaram, Shanthy; Sinha, Rajeshwar P.

doi:10.1016/j.genrep.2016.09.005

Cited by 14 publications

(4 citation statements)

References 54 publications

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“…Generally, photo-crosslinking in proteins often occurs between several photoactive residues, such as Cys, His, Trp, and Tyr, forming disulfide, histidine–lysine, or dityrosine linkages. − In our case, the photo-crosslinkingoccurred intermolecularly via nonreducible covalent bondsmost likely involves Tyr residues, given their high abundance in C-PC relative to the other photoactive residues (Figure S3A). Moreover, it was noticed that most of the Tyr residues in C-PC locate around the chromophores and at the interfaces across α- and β-subunits (Figure ), making it possible for the photo-crosslinking to happen intermolecularly across separate chains, as was suggested by SDS-PAGE gels. Indeed, the involvement of Tyr residues in photo-crosslinking was experimentally corroborated by the Tyr-derived radicals (direct EPR, Figure S11B) and dityrosine species (dityrosine-specific fluorescence, Figure S11C) extensively formed in irradiated C-PC at pH 5.0.…”

Section: Resultsmentioning

confidence: 96%

Tuning C-Phycocyanin Photoactivity via pH-Mediated Assembly–Disassembly

2021

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Environment-triggered protein conformational changes have garnered wide interest in both fundamental research, for deciphering in vivo acclimatory responses, and practical applications, for designing stimuli-responsive probes. Here, we propose a protein−chromophore regulatory mechanism that allows for manipulation of C-phycocyanin (C-PC) from Spirulina platensis by environmental pH and UV irradiation. Using small-angle X-ray scattering, a pHmediated C-PC assembly−disassembly pathway, from monomers to nonamers, was unraveled. Such flexible protein matrices impart tunability to the embedded tetrapyrroles, whose photochemical behaviors were found to be modulated by protein assembly states. UV irradiation on C-PC triggers pH-dependent singlet oxygen ( 1 O 2 ) generation and conformational changes. Intermolecular photo-crosslinking occurs at pH 5.0 via dityrosine species, which bridges solution-based C-PC oligomers into unprecedented dodecamers and 24-mers. These supramolecular assemblies impart C-PC at pH 5.0, which significantly enhanced 1 O 2 yield, fluorescence, and photostability relative to those at other pH values, a finding that makes C-PC appealing for tumor-targeted photodynamic therapy.

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Section: Resultsmentioning

confidence: 96%

Tuning C-Phycocyanin Photoactivity via pH-Mediated Assembly–Disassembly

2021

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“…The binding mechanisms of CIP and PC are similar to that of Hg 2+ . The binding of CIP at specific sites will also cause displacement of the PCBs and affect the photophysical properties of PC [32][33][34][35].…”

Section: Introductionmentioning

confidence: 99%

“…Hg 2+ and CIP can interact electrostatically with PC and covalently bind to the thiol group of Cys. Both can alter the PC structure and quench fluorescence[31][32][33][34][35]. As shown in figure1, under ambient light conditions, the PCB chromophore was attached to the Cys of the protein through a thioether bond, showing blue fluorescence.…”

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confidence: 99%

Construction of fluorescent logic gates for the detection of mercury(II) and ciprofloxacin based on phycocyanin

Dong¹,

Girmatsion²,

Wang³

et al. 2022

Methods Appl. Fluoresc.

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Chemical pollutants such as heavy metals and antibiotics in the environment pose a huge threat to humans and animals. Our studies have demonstrated that the fluorescence of phycocyanin showed quenching responses towards both mercury (Hg2+) and ciprofloxacin (CIP), which acted in accordance with the “OR” molecular logic gate. In order to discriminate Hg2+ and CIP in application scenarios, cysteine (Cys) was utilized to design another “INHIBIT” logic gate, in which Hg2+ and Cys were the two inputs. Thus, an intelligent biosensor with dual-target identification capacity was successfully developed by using a fluorescent natural protein in an ingenious logic gate system.

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“…Phycocyanin is a natural protein with red fluorescence from cyanobacteria for the photosynthetic apparatus, converting the solar energy into their chemical energy (Patel et al, 2005). The phycocyanin contains phycocyanobilins (linear tetrapyrrole molecules with florescent property) and cysteine amino acid residues (Kannaujiya et al, 2016). The energy transitions of pi-pi* within the florescent molecules are related with the photoluminescence characteristics (Stoll et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

In vitro assessment of the toxicity of lead (Pb2+) to phycocyanin

Tan

Chi

et al. 2018

Chemosphere

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This work reports the influence of lead (Pb) on fluorescence characteristics and protein structure of phycocyanin molecules experimentally in vitro. The fluorescence intensity decreases with the increasing concentration of Pb from 0 to 5 × 10 mol L, showing the fluorescence quenching of phycocyanin by Pb. The quenching process is suggested to be static regarding the calculation results and the experimental results of time-resolved fluorescence decay profiles. The synchronous fluorescence spectra show that the effect of Pb on the Tyr residues of phycocyanin is more significant than the Trp residues. The forming of aggregation by the interaction of Pb with phycocyanin molecules is suggested from the results of resonance light scattering spectra. The UV-Vis spectra of the protein skeleton of phycocyanin have a red-shift of about 10 nm with increasing the Pb concentration from 0 to 5 × 10 mol L, indicating a change in the protein skeleton and its secondary structure. With the increasing Pb concentration, the two negative peaks (209 nm and 218 nm) on circular dichroism spectra become smaller, showing a decrease of the α-helix structure. These results may give people a deeper understanding of that how the heavy metal (Pb) can affect the chemo-physical properties of phycocyanin.

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Structural and functional dynamics of tyrosine amino acid in phycocyanin of hot-spring cyanobacteria: A possible pathway for internal energy transfer

Cited by 14 publications

References 54 publications

Tuning C-Phycocyanin Photoactivity via pH-Mediated Assembly–Disassembly

Tuning C-Phycocyanin Photoactivity via pH-Mediated Assembly–Disassembly

Construction of fluorescent logic gates for the detection of mercury(II) and ciprofloxacin based on phycocyanin

In vitro assessment of the toxicity of lead (Pb2+) to phycocyanin

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