Similarity among the Drosophila (6-4)photolyase, a human photolyase homolog, and the DNA photolyase-blue-light photoreceptor family.
ABSTRACT Ultraviolet light (UV)-induced DNA damage can be repaired by DNA photolyase in a light-dependent manner. Two types of photolyase are known, one specific for cyclobutane pyrimidine dimers (CPD photolyase) and another specific for pyrimidine (6-4) pyrimidone photoproducts[(6-4)photolyase]. In contrast to the CPD photolyase, which has been detected in a wide variety of organisms, the (6-4)photolyase has been found only in Drosophila melanogaster. In the present study a gene encoding the Drosophila(6-4)photolyase ws cloned, and the deduced amino acid sequence of the product was found to be similar to the CPD photolyase and to the blue-light photoreceptor of plants. A homolog of the Drosophila (6-4)photolyase gene was also cloned from human cells.
- SourceAvailable from: Dana F SchroederSelected Topics in DNA Repair, 10/2011; , ISBN: 978-953-307-606-5
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ABSTRACT: Flavin cofactor is known to perform diverse biological functions. Recently, its role as a photoreceptor has been identified. So far, three classes of photoactive flavoproteins have been recognized: phototropin with LOV (Light, Oxygen and Voltage) domain, blue light sensory protein with BLUF (Blue Light sensing Using Flavin adenine dinucleotide) domain and photolyase/cryptochrome protein with PHR (Photolyase Homology Region) domain. Photochemistry of flavin is the key to unravel the reaction mechanisms of photoactive flavoproteins in their biological functions such as DNA repair or signal transduction. Vibrational (Infrared and Raman) spectroscopy is a useful and sensitive tool to investigate the photochemistry of flavin in protein environments and has significantly contributed to elucidate the reaction mechanisms of these photoactive proteins. This study will survey recent advances in vibrational spectroscopic studies on this topic and remaining questions to be answered.Spectroscopy 01/2011; 25(6):261-269. DOI:10.3233/SPE-2011-0515 · 0.83 Impact Factor
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ABSTRACT: The circadian oscillator is composed of a transcription/translation-based autoregulatory feedback loop in which Cryptochromes and Periods function as negative regulators for their own gene expression. Although post-translational modifications such as phosphorylation of these regulators appear crucial for circadian time-keeping mechanism, less is known about responsible protein kinases and their contribution to the function of the regulators. We found that mitogen-activated protein kinase (MAPK) associates with and phosphorylates mouse Cryptochromes (mCRY1 and mCRY2). Mass spectrometry analysis identified Ser265 and Ser557 of mCRY2 to be in vitro phospho-acceptor residues. Mutations of both the Ser residues to Ala completely abolished MAPK-mediated mCRY2 phosphorylation, suggesting that the two residues are the principal phosphorylation sites in mCRY2. Similarly, MAPK phosphorylates mCRY1 at Ser247, a site corresponding to Ser265 of mCRY2. An effect of the Ser phosphorylation was investigated by mutating Ser247 of mCRY1 and Ser265 of mCRY2 to Asp, which resulted in attenuation of each mCRYs' ability to inhibit BMAL1: CLOCK-mediated transcription, whereas a similar mutation at Ser557 of mCRY2 induced no measurable change in its activity. These results illustrate a model of MAPK-mediated negative regulation of mCRY function by phosphorylation at the specific Ser residue.Genes to Cells 09/2004; 9(8):697-708. DOI:10.1111/j.1356-9597.2004.00758.x · 2.86 Impact Factor