Enhancement of Photophysical and Photosensitizing Properties of Flavin Adenine Dinucleotide by Mutagenesis of the C‐Terminal Extension of a Bacterial Flavodoxin Reductase

Valle, Lorena; Abatedaga, Inés; Vieyra, Faustino E. Morán; Bortolotti, Ana; Cortez, Néstor; Borsarelli, Claudio D.

doi:10.1002/cphc.201402774

Cited by 10 publications

(17 citation statements)

References 52 publications

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“…The emission band of dBlsA was progressively shifted to the blue as temperature decreased, whereas for the fluorescence emission of free FAD in buffer was almost independent of temperature (data not shown). These results confirm that as temperature decreases, the cofactor in dBlsA senses a less polar nanoenvironment than in bulk buffer .…”

Section: Resultssupporting

confidence: 74%

“…), and hence, this should be the case. Thus, the absorbance ratio between the vibrational bands at the red‐shoulder and at the maximum, for example A sh / A max , was proposed as convenient parameter to monitor the environmental changes of the nanospace around FAD . Figure b shows that ratio A sh / A max for dBlsA is constant between 15.6 and 24.2°C, but it is strongly decreased at higher temperatures up to a closer value observed for free FAD, being the latter not sensitive to temperature.…”

Section: Resultsmentioning

confidence: 99%

“…Fluorescence lifetimes were registered using a Tempro‐01 time‐correlated single photon counting (TCSPC) system (Horiba, Glasgow, UK) as described before, as well as the data analysis . Briefly, the fluorescence intensity decays obtained by excitation with a pulsed blue‐LED (Nanoled ® 461 ± 27 nm, 1 MHz, Horiba) were fitted with the fluorescence decay analysis software DAS6 ® (Horiba) by deconvolution of the pulse function (obtained with a diluted Ludox ® suspension at the excitation wavelength) using a multiexponential model function .…”

Section: Methodsmentioning

confidence: 99%

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Integration of Temperature and Blue‐Light Sensing in Acinetobacter baumannii Through the BlsA Sensor

Abatedaga

Valle

Golic

et al. 2017

Photochem & Photobiology

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BlsA is a BLUF photoreceptor present in Acinetobacter baumannii, responsible for modulation of motility, biofilm formation and virulence by light. In this work, we have combined physiological and biophysical evidences to begin to understand the basis of the differential photoregulation observed as a function of temperature. Indeed, we show that blsA expression is reduced at 37°C, which correlates with negligible photoreceptor levels in the cells, likely accounting for absence of photoregulation at this temperature. Another point of control occurs on the functionality of the BlsA photocycle itself at different temperatures, which occurs with an average quantum yield of photoactivation of the signaling state of 0.20 ± 0.03 at 15°C < T < 25°C, but is practically inoperative at T > 30°C, as a result of conformational changes produced in the nanocavity of FAD. This effect would be important when the photoreceptor is already present in the cell to avoid almost instantaneously further signaling process when it is no longer necessary, for example under circumstances of temperature changes possibly faced by the bacteria. This complex interplay between light and temperature would provide the bacteria clues of environmental location and dictate/modulate light photosensing in A. baumannii.

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Section: Resultssupporting

confidence: 74%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Integration of Temperature and Blue‐Light Sensing in Acinetobacter baumannii Through the BlsA Sensor

Abatedaga

Valle

Golic

et al. 2017

Photochem & Photobiology

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“…These Δ A 0 values were used for the calculation of the quantum yield of HF • formation (

Φ_{{H F}^{•}}

) with Eqn. :

Φ_{{H F}^{•}} = \frac{normalΔ A_{0}^{560}}{normalΔ A_{0}^{710}} \frac{ε_{normalT}^{710}}{ε_{{normalH normalF}^{•}}^{560}} Φ_{T}

where Φ T is the triplet quantum yield of the flavins;

ε_{T}^{710}

= 7200 M −1 cm −1 and

ε_{{H F}^{•}}^{560}

= 4400 M −1 cm −1 are the extinction coefficients of 3 F* and HF • , respectively . Table shows that

Φ_{{H F}^{•}}

in AOT RM is about one order of magnitude lower than that in aqueous buffer, with a slight increases with w 0 .…”

Section: Resultsmentioning

confidence: 77%

“…Steady‐state and time‐resolved techniques used in this work were fully described in previous reports …”

Section: Methodsmentioning

confidence: 99%

Nanoenvironmental effect in AOT reverse micelles on the triplet excited state properties of flavins and quenching by molecular oxygen

Valle

Vieyra

Borsarelli

2016

J of Physical Organic Chem

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The triplet quantum yield (ΦT) and lifetime (τT) of the lowest excited triplet state of the flavins (3F*), for example, lumiflavin, riboflavin, flavin mononucleotide, and flavin adenine dinucleotide were determined by laser‐flash photolysis experiments in Aerosol‐OT reverse micelles (AOT RM) dispersed in n‐hexane as function of the amount of water dissolved w0 = [H2O]/[AOT]. The energy‐transfer quenching of 3F* by triplet molecular oxygen 3O2 to produce singlet molecular oxygen (1O2) was also evaluated by applying a simple pseudophase model for the 3O2 partition between the organic solvent and the AOT RM. The quantum yield of 1O2 generation by the flavins was also calculated. The results are discussed as a function of the nanoenvironmental changes produced in the constrained aqueous interior of the AOT RM as the amount of dispersed water increases. Copyright © 2016 John Wiley & Sons, Ltd.

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New insights into the operative network of FaEO, an enone oxidoreductase from Fragaria x ananassa Duch.

et al. 2017

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The 2-methylene-furan-3-one reductase or Fragaria x ananassa Enone Oxidoreductase (FaEO) catalyses the last reductive step in the biosynthesis of 4-hydroxy-2,5-dimethyl-3(2H)-furanone, a major component in the characteristic flavour of strawberries. In the present work, we describe the association between FaEO and the vacuolar membrane of strawberry fruits. Even if FaEO lacks epitopes for stable or transient membrane-interactions, it contains a calmodulin-binding region, suggesting that in vivo FaEO may be associated with the membrane via a peripheral protein complex with calmodulin. Moreover, we also found that FaEO occurs in dimeric form in vivo and, as frequently observed for calmodulin-regulated proteins, it may be expressed in different isoforms by alternative gene splicing. Further mass spectrometry analysis confirmed that the isolated FaEO consists in the already known isoform and that it is the most characteristic during ripening. Finally, a characterization by absorption spectroscopy showed that FaEO has specific flavoprotein features. The relevance of these findings and their possible physiological implications are discussed.

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Enhancement of Photophysical and Photosensitizing Properties of Flavin Adenine Dinucleotide by Mutagenesis of the C‐Terminal Extension of a Bacterial Flavodoxin Reductase

Cited by 10 publications

References 52 publications

Integration of Temperature and Blue‐Light Sensing in Acinetobacter baumannii Through the BlsA Sensor

Integration of Temperature and Blue‐Light Sensing in Acinetobacter baumannii Through the BlsA Sensor

Nanoenvironmental effect in AOT reverse micelles on the triplet excited state properties of flavins and quenching by molecular oxygen

New insights into the operative network of FaEO, an enone oxidoreductase from Fragaria x ananassa Duch.

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