Similarity among the Drosophila (6-4)photolyase, a human photolyase homolog, and the DNA photolyase-blue-light photoreceptor family
Radiation Biology Center, Kyoto University, Kyoto, Japan. Science
(Impact Factor: 33.61).
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.
Available from: Mario Pedrazzoli
- "Neste ponto fica claro que há uma complexidade crescente no possível mecanismo do relógio circadiano molecular, mas ainda nesta mesma época uma dupla de genes parálogos, os genes Cryptocromo 1 e 2 (Cry 1 e Cry2) são adicionados na lista dos genes relógio. Estes genes são membros da família de receptores de luz azul em plantas (Todo e cols., 1996; van der Spek e cols., 1996; Hsu e cols.,1996; Kobayashi e cols., 1998). "
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DESCRIPTION: Esta tese constitui um recorte de parte de minha produção científica em genética do sono e dos ritmos circadianos que se iniciou durante o meu pós-doutorado na Universidade de Stanford em 1998. Mais especificamente se refere à parte de minha pesquisa voltada ao estudo dos genes relógio, sua influência na determinação dos cronotipos ou no estabelecimento da Síndrome da Fase Atrasada de Sono, ao estudo da distribuição das freqüências alélicas destes genes em diferentes grupos étnicos e ao estudo do gene Per3 em primatas. A interpretação dos resultados dos nossos estudos nos últimos anos, seu significado teórico e complementaridade nos leva a uma nova visão da interação entre as relações astronômicas entre a Terra e o Sol e a expressão gênica necessária a adaptação dos seres vivos ao ciclo claro/escuro natural, visão esta que tem como corolário uma visão da evolução humana centrada no ponto de vista da adaptação às variações anuais do ciclo claro/escuro ao longo do clina latitudinal no nosso planeta e as consequências para a saúde humana na sociedade urbana moderna.
A construção dessa visão que será apresentada neste texto é resultante da minha formação na pós-graduação no Departamento de Psicobiologia da Universidade Federal de São Paulo um departamento em essência multidisciplinar, das minhas relações e leituras científicas, das minhas idiossincrasias intelectuais e intuições, mas principalmente, e obviamente, dos resultados dos estudos feitos em conjunto com os meus alunos de pós-graduação.
Available from: Yibin Wang
- "However, microorganisms that thrive in polar ecosystems have developed a variety of strategies to tolerate stressful growth conditions . DNA photolyases has been reported in bacteria , fungi, plants, invertebrates, and vertebrates, and may have played an important role in the evolution of the earliest organisms on primordial Earth   . Although extensive research has been conducted on adaptations of polar organisms to stress factors, few studies have focused on the mechanisms so far. "
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ABSTRACT: Bacteria living in the Antarctic region have developed several adaptive features for growth and survival under extreme conditions. Chlamydomonas sp. ICE-Lis well adapted to high levels of solar UV radiation. A putative photolyase was identified in the Chlamydomonas sp. ICE-L transcriptome. The complete cDNA sequence was obtained by RACE-PCR. This PHR encoding includes a polypeptide of 579 amino acids with clear photolyase signatures belonging to class II CPD-photolyases, sharing a high degree of homology with Chlamydomonas reinhardtii (68%). Real-time PCR was performed to investigate the potential DNA damage and responses following UVB exposure. CPD photolyase mRNA expression level increased over 50-fold in response to UVB radiation for 6h. Using photolyase complementation assay, we demonstrated that DNA photolyase increased photo-repair more than 116-fold in Escherichia coli strain SY2 under 100μw/cm(2) UVB radiation. To determine whether photolyase is active in vitro, CPD photolyase was over-expressed. It was shown that pyrimidine dimers were split by the action of PHR2. This study reports the unique structure and high activity of the enzyme. These findings are relevant for further understanding of molecular mechanisms of photo-reactivation, and will accelerate the utilization of photolyase in the medical field.
Copyright © 2015 Elsevier B.V. All rights reserved.
Available from: Sehyung Cho
- "Although more studies are required to discover species-specific roles of PRMT5, we expect that our observations may have resulted from the different structures of CRYs, since the amino acid composition and length of the C-terminal region of mammalian CRY are quite different from that of Arabidopsis and Drosophila CRY , . In addition, some species-specific mechanisms of circadian clock regulation by CRY have been previously suggested . "
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ABSTRACT: Circadian clocks are the endogenous oscillators that regulate rhythmic physiological and behavioral changes to correspond to daily light-dark cycles. Molecular dissections have revealed that transcriptional feedback loops of the circadian clock genes drive the molecular oscillation, in which PER/CRY complexes inhibit the transcriptional activity of the CLOCK/BMAL1 heterodimer to constitute a negative feedback loop. In this study, we identified the type II protein arginine methyltransferase 5 (PRMT5) as an interacting molecule of CRY1. Although the Prmt5 gene was constitutively expressed, increased interaction of PRMT5 with CRY1 was observed when the Per1 gene was repressed both in synchronized mouse liver and NIH3T3 cells. Moreover, rhythmic recruitment of PRMT5 and CRY1 to the Per1 gene promoter was found to be associated with an increased level of histone H4R3 dimethylation and Per1 gene repression. Consistently, decreased histone H4R3 dimethylation and altered rhythmic Per1 gene expression were observed in Prmt5-depleted cells. Taken together, these findings provide an insight into the link between histone arginine methylation by PRMT5 and transcriptional regulation of the circadian Per1 gene.
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