The Effect of Tryptophan on UV‐induced DNA Photodamage

Oladepo, Sulayman A.; Loppnow, Glen R.

doi:10.1111/j.1751-1097.2010.00745.x

Cited by 4 publications

(2 citation statements)

References 35 publications

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“…In addition, tryptophan, an aromatic amino acid, has been reported to absorb UVC and UVB at 260-305 nm (Holiday, 1936). Furthermore, it has been shown that when tryptophan-containing DNA solutions are exposed to UVCs, tryptophan preferentially absorbs UVCs and reduces DNA damage (Oladepo and Loppnow, 2010). Therefore, it is possible that tryptophan is synthesized to protect DNA from UVC-induced DNA damage, and intracellular tryptophan concentration and localization should be measured before and after UVC irradiation.…”

Section: Genes Expression By Uvc Exposurementioning

confidence: 99%

Light response of Vibrio parahaemolyticus

et al. 2022

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Light is one of the most critical stimuli in the majority of living organisms. In the last two decades, blue light (BL) has become a major subject of attention because of developments in light-emitting diodes (LED). The effects of BL on eukaryotic organisms and phototrophic prokaryotes have been well studied, but the knowledge of its effects on non-phototrophic prokaryotes remains unclear. Since BL can penetrate seawater, it is expected that most prokaryotes living in the ocean possess molecular mechanisms which protect against BL. The aim of this study is to assess the molecular mechanisms of Vibrio parahaemolyticus cells against BL as a marine bacterial model compared to other wavelength light exposures. Physiological and transcriptomic analyses of BL-exposed cells compared to other light treated cells revealed the highest ROS fold change, the highest number of differentially expressed genes (DEGs), and up-regulation in the gene responsible to not only compatible solute such as glycine betaine and ectoine but also iron-sulfur biosynthesis related to ROS formation. Furthermore, red light (RL) up-regulated the expression of cryptochrome DASH, a protein known to be excited by BL, and orange light (OL) decreased the expression of thermostable direct hemolysin (TDH), suggesting that OL attenuates the virulence of V. parahaemolyticus. In addition, the expression of VtrA (V. parahaemolyticus type III secretion system 2 (T3SS2) regulator A) but not VtrB (V. parahaemolyticus T3SS2 regulator B) increased under both light treatments, indicating that light exposure is unlikely to be involved in T3SS2-mediated pathogenicity. These results expand our knowledge on unique light responses in non-phototrophic marine prokaryotes.

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Section: Genes Expression By Uvc Exposurementioning

confidence: 99%

Light response of Vibrio parahaemolyticus

et al. 2022

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“…Increased knowledge about DNA damage and its direct link to cancer drives an urgent need for an analytical technique which is not only selective and sensitive but can detect damage in a large number of sequences simultaneously. But to study UV irradiation of ssDNA in vitro followed by its detection using MBs, a typical experiment involves the irradiation of each sample under study in a cuvette . Major limitations of this latter assay are that only a few samples can be done simultaneously and it is time consuming.…”

Section: Introductionmentioning

confidence: 99%

Multiplexed, UVC‐Induced, Sequence‐Dependent DNA Damage Detection

Nair

Loppnow

2013

Photochem & Photobiology

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The exposure of DNA to ultraviolet (UV) radiation causes sequence-dependent damage. Thus, there is a need for an analytical technique that can detect damage in large numbers of DNA sequences simultaneously. In this study, we have designed an assay for UVC-induced DNA damage in multiple oligonucleotides simultaneously by using a 96-well plate and a novel automated sample mover. The UVC-induced DNA damage is measured using smart probes, analogs of molecular beacons in which guanosine nucleotides act as the fluorescence quencher. Our results show that the oligonucleotide damage constants obtained with this method are reproducible and similar to those obtained in cuvettes. The calibration curve for poly-dT shows good linearity (R(2) = 0.96), with limits of detection (LOD) and quantification (LOQ) equal to 55 and 183 nm, respectively. The results show that the damage kinetics upon irradiation is sensitive to the different types of photoproducts formed in the different sequences used; i.e. poly-A oligonucleotides containing guanine are damaged at a faster rate than poly-A oligonucleotides containing either thymine or cytosine. Thus, detecting DNA damage in a 96-well plate and quantifying the damage with smart probes are a simple, fast and inexpensive mix-and-read technique for multiplexed, sequence-specific DNA damage detection.

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Molecular Beacon Probes of Oligonucleotides Photodamaged by Psoralen

Shire

Loppnow

2012

Photochem & Photobiology

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Ultraviolet A (UVA)-irradiated 4'-hydroxymethyl-4,5',8-trimethyl psoralen (HMT) in the presence of a poly-dT(17) and dA(7) TTA(8) oligonucleotides produces HMT-dT(17) and HMT-dA(7) TTA(8) adducts in aqueous solution. In this article, we determine whether these HMT-dT(17) and HMT-dA(7) TTA(8) adducts can be detected with a molecular beacon (MB) probe. We measure the degree of damage in dT(17) and dA(7) TTA(8) solutions containing UVA-activated HMT via monitoring the decrease in MB fluorescence. Photoproduct formation is confirmed by MALDI-TOF MS (matrix-assisted laser desorption/ionization time-of-fight mass spectrometry measurements) and absorption spectroscopy. The MB fluorescence decreases upon UVA irradiation in the presence of HMT with a single-exponential time constants of 114.2 ± 6.5 min for HMT-dT(17) adducts and 677.8 ± 181.8 min for HMT-dA(7) TTA(8) adducts. Our results show that fluorescent MB probes are a selective, robust and accurate tool for detecting UVA-activated HMT-induced DNA damage.

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The Effect of Tryptophan on UV‐induced DNA Photodamage

Cited by 4 publications

References 35 publications

Light response of Vibrio parahaemolyticus

Light response of Vibrio parahaemolyticus

Multiplexed, UVC‐Induced, Sequence‐Dependent DNA Damage Detection

Molecular Beacon Probes of Oligonucleotides Photodamaged by Psoralen

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