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1.
Food Sci Nutr ; 8(7): 3335-3345, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32724598

RESUMO

Gardenia (Gardenia jasminoides J. Ellis) is regarded as an edible medicine plant in China. Here, gardenia flower polysaccharide fraction (GFPF) was extracted by water at 90°C and its chemical composition, rheological properties, and antioxidant activities of GFPF were investigated. The GFPF extraction yield was 18.04 ± 1.81% (W/W) and mainly comprised neutral sugars (46.83 ± 3.14%), uronic acid (35.21 ± 0.17%), protein (1.63 ± 0.34%), and total phenol (9.49 ± 0.08 mgGAE/g). Galacturonic acid (41.05 ± 0.59%) was the main monosaccharide, and galactose, glucose, arabinose, rhamnose, xylose, mannose, and glucuronic acid were also detected in GFPF. Its degree of esterification was 32.76 ± 1.52%. FT-IR spectra analysis showed a similar absorption pattern between GFPF and pectin from apple. The results suggested that GFPF was low methoxy pectin. Thermogravimetric analysis and zeta potential analysis indicated that the pectin was stable under high temperature and alkaline condition. Steady rheology showed that the GFPF dispersion was a shear thinned pseudoplastic fluid with high apparent viscosities at concentration above 2%. The degree of pseudoplasticity of the solutions increased with the concentrations increased and the temperatures decreased. DPPH and ABTS free radical scavenging assay indicated that GFPF had relatively high antioxidant activity. The results showed that gardenia flower was rich in pectin polysaccharides with low methoxy pectin. It had high apparent viscosities at concentration above 2% and had good antioxidant activity. The data suggested that GFPF can be a new resource of low methoxy pectin with potential application as thicker or gelling agents in food industry.

2.
Biochem Biophys Res Commun ; 513(3): 740-745, 2019 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-30992133

RESUMO

RecFOR and RecA are key recombination factors in Deinococcus radiodurans, a bacterium that possesses robust DNA repair capability and is also naturally transformable. While RecFOR functioning as a RecA loader during DNA repair has been established, their relative roles in transformation need further exploration. Here, we constructed recFOR and recA deletion mutants of D. radiodurans, and investigated the effect of these mutations on DNA transformation. recA deletion causes defects in both plasmid and chromosomal transformation. However, it was found that recFOR is not involved in chromosomal transformation, and that only recO and recR mutations compromise plasmid transformation. How recO, recR and recA mutations influence plasmid transformation was further examined by complementation plasmids. Interestingly, the transformation process remains defective in the recA mutant, but gets restored in the recO and recR mutants. This indicates that unlike RecA, RecOR may not be essential for DNA uptake. Therefore, we provide evidence that RecFOR is dispensable for RecA to protect incoming exogenous DNA and to catalyze recombination during transformation. Instead, RecO and RecR are likely to promote later steps in plasmid transformation.

3.
Food Chem ; 286: 329-337, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-30827615

RESUMO

The effects of exogenous progesterone (PROG) on chilling injury (CI) in postharvest banana fruit were investigated. Concentration screening tests showed that 10-5 mol/l PROG was most effective in reducing CI in banana fruit stored for 25 d at 5 ±â€¯1 °C, but did not markly increase PROG content of pulps. This PROG treatment significantly reduced the electrolyte leakage, levels of malondialdehyde, O2- production rate and H2O2 contents in banana compared with control fruit. The PROG treatment caused an early induction of alternative oxidase (AOX) at the transcript and protein level to reduce the generation of O2- and H2O2. PROG treatment also enhanced the transcript levels and activities of antioxidant enzymes and maintained higher levels of reduced glutathione and ascorbic acid than the control fruit. These results suggested that PROG attenuating CI in banana fruit may be attributed to the induction of AOX and the improvement of enzyme and non-enzymatic antioxidant defenses.


Assuntos
Antioxidantes/metabolismo , Proteínas Mitocondriais/metabolismo , Musa/efeitos dos fármacos , Oxirredutases/metabolismo , Proteínas de Plantas/metabolismo , Progesterona/farmacologia , Antioxidantes/química , Temperatura Baixa , Eletrólitos/metabolismo , Frutas/efeitos dos fármacos , Frutas/metabolismo , Glutationa/metabolismo , Peróxido de Hidrogênio/análise , Malondialdeído/metabolismo , Proteínas Mitocondriais/genética , Musa/metabolismo , Oxirredutases/genética , Proteínas de Plantas/genética , Espécies Reativas de Oxigênio/metabolismo
4.
Mol Microbiol ; 106(4): 518-529, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28862774

RESUMO

RecF, together with the recombination mediators RecO and RecR, is required in the RecFOR homologous recombination repair pathway in bacteria. In this study, a recF-dr1088 operon, which is highly conserved in the Deinococcus-Thermus phylum, was identified in Deinococcus radiodurans. Interaction between DRRecF and DR1088 was confirmed by yeast two-hybrid and pull-down assays. DR1088 exhibited some RecO-like biochemical properties including single/double-stranded DNA binding activity, ssDNA binding protein (SSB) replacement ability and ssDNA (with or without SSB) annealing activity. However, unlike other recombination proteins, dr1088 is essential for cell viability. These results indicate that DR1088 might play a role in DNA replication and DNA repair processes.


Assuntos
Deinococcus/genética , Deinococcus/metabolismo , Proteínas de Bactérias/metabolismo , Reparo do DNA , Replicação do DNA/fisiologia , DNA Bacteriano/metabolismo , DNA de Cadeia Simples/metabolismo , Proteínas de Ligação a DNA/metabolismo , Recombinases Rec A/metabolismo , Recombinação Genética , Reparo de DNA por Recombinação/fisiologia
5.
Int J Radiat Biol ; 92(5): 273-80, 2016 05.
Artigo em Inglês | MEDLINE | ID: mdl-26948123

RESUMO

Purpose To investigate the function basis of the recently discovered response regulator, drRRA (DNA damage response regulator A) in Deinococcus radiodurans, we compared the proteomic profile of the radiation-sensitive drRRA mutant with that of wild-type strain under both non-stress and gamma radiation treatment. Materials and methods Total proteins of D. radiodurans cells were subjected to two-dimension electrophoresis. Protein spots in 2-Dimension gels were silver stained and scanned. Spots that changed significantly in expression levels were selected for mass spectrometry analysis. Seven genes encoding representative proteins were knocked out for stress resistance analysis. Results A total of 52 proteins displayed significant expression level changes at least 1.5-fold in the mutant relative to wild-type strain under non-stress conditions, with 31 repressed and 21 induced proteins, which might affect the cell response of D. radiodurans to gamma radiation. The proteins were distributed into functional groups including stress response, metabolism, and function unknown. Disruptions of several altered proteins including DRA0259 (Catalase E) and DR1538 (Osmotically inducible protein C), reduced the antioxidant activity of D. radiodurans. Conclusion Combined with our previous result of transcriptional profile, we further confirmed that inactivation of DrRRA affects the expression of various stress response systems.


Assuntos
Proteínas de Bactérias/metabolismo , Deinococcus/metabolismo , Deinococcus/efeitos da radiação , Proteínas de Choque Térmico/metabolismo , Estresse Oxidativo/fisiologia , Proteoma/metabolismo , Proteínas de Ligação a DNA , Relação Dose-Resposta à Radiação , Raios gama , Estresse Oxidativo/efeitos da radiação , Doses de Radiação , Tolerância a Radiação/fisiologia
6.
Sci Rep ; 5: 10479, 2015 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-25990684

RESUMO

Nucleic acid based molecular device is a developing research field which attracts great interests in material for building machinelike nanodevices. G-quadruplex, as a new type of DNA secondary structures, can be harnessed to construct molecular device owing to its rich structural polymorphism. Herein, we developed a switching system based on G-quadruplexes and methylazacalix[6]pyridine (MACP6). The induced circular dichroism (CD) signal of MACP6 was used to monitor the switch controlled by temperature or pH value. Furthermore, the CD titration, Job-plot, variable temperature CD and (1)H-NMR experiments not only confirmed the binding mode between MACP6 and G-quadruplex, but also explained the difference switching effect of MACP6 and various G-quadruplexes. The established strategy has the potential to be used as the chiral probe for specific G-quadruplex recognition.


Assuntos
Calixarenos/química , Computadores Moleculares , DNA/química , Quadruplex G , Oligonucleotídeos/química , Dicroísmo Circular , Proteínas de Ligação a DNA/química , Concentração de Íons de Hidrogênio , Modelos Moleculares , Simulação de Acoplamento Molecular , Ressonância Magnética Nuclear Biomolecular , Temperatura
7.
J Bacteriol ; 197(12): 2048-61, 2015 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-25868646

RESUMO

UNLABELLED: In archaea, the NurA nuclease and HerA ATPase/helicase, together with the Mre11-Rad50 complex, function in 3' single-stranded DNA (ssDNA) end processing during homologous recombination (HR). However, bacterial homologs of NurA and HerA have not been characterized. From Deinococcus radiodurans, we identified the manganese-dependent 5'-to-3' ssDNA/double-stranded DNA (dsDNA) exonuclease/endonuclease NurA (DrNurA) and the ATPase HerA (DrHerA). These two proteins stimulated each other's activity through direct protein-protein interactions. The N-terminal HAS domain of DrHerA was the key domain for this interaction. Several critical residues of DrNurA and DrHerA were verified by site-directed mutational analysis. Temperature-dependent activity assays confirmed that the two proteins had mesophilic features, with optimum activity temperatures 10 °C to 15 °C higher than their optimum growth temperatures. Knocking out either nurA or herA affected cell proliferation by shortening the growth phase, especially for growth at a high temperature (37 °C). In addition, both mutant strains displayed almost 10-fold-reduced intermolecular recombination efficiency, indicating that DrNurA and DrHerA might be involved in homologous recombination in vivo. However, single- and double-gene deletions did not show significantly decreased radioresistance. Our results confirmed that the biochemical activities of bacterial NurA and HerA proteins were conserved with archaea. Our phenotypical results suggested that these proteins might have different functions in bacteria. IMPORTANCE: Deinococcus radiodurans NurA (DrNurA) was identified as a manganese-dependent 5'-to-3' ssDNA/dsDNA exonuclease/endonuclease, and Deinococcus radiodurans HerA (DrHerA) was identified as an ATPase. Physical interactions between DrNurA and DrHerA explained mutual stimulation of their activities. The N-terminal HAS domain on DrHerA was identified as the interaction domain. Several essential functional sites on DrNurA and DrHerA were characterized. Both DrHerA and DrNurA showed mesophilic biochemical features, with their optimum activity temperatures 10 °C to 15 °C higher than their optimum growth temperatures in vitro. Knockout of nurA or herA led to abnormal cell proliferation and reduced intermolecular recombination efficiency but no obvious effect on radioresistence.


Assuntos
Proteínas de Bactérias/metabolismo , Deinococcus/metabolismo , Adenosina Trifosfatases/genética , Adenosina Trifosfatases/metabolismo , Sequência de Aminoácidos , Proteínas de Bactérias/genética , Proliferação de Células , Biologia Computacional , Reparo do DNA/fisiologia , DNA Bacteriano/genética , Deleção de Genes , Regulação Bacteriana da Expressão Gênica/fisiologia , Regulação Enzimológica da Expressão Gênica , Temperatura Alta , Modelos Moleculares , Mutagênese Sítio-Dirigida , Óperon , Conformação Proteica
8.
Biochim Biophys Acta ; 1840(10): 3052-7, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25086254

RESUMO

BACKGROUND: A new G-quadruplex structure located in the B-cell CLL/lymphoma 2 (Bcl-2) P1 promoter and its physiological function related to Bcl-2 transcription have been studied to find a potential anticancer therapeutic target. METHODS: Absorption, polyacrylamide gel electrophoresis, fluorescence, circular dichroism, and nuclear magnetic resonance spectra have been employed to determine G-quadruplex structure and the interaction between G-quadruplex and phenanthrolin-dicarboxylate. Real time polymerase chain reaction and luciferase assay were done to assess the physiological function of the G-quadruplex structure. RESULTS: The UV-melting and polyacrylamide gel electrophoresis studies show that the p32 DNA sequence forms an intramolecular G-quadruplex structure. Circular dichroism and nuclear magnetic resonance spectra indicate that the G-quadruplex is a hybrid-type structure with four G-tetrads. Fluorescence spectra show that a phenanthroline derivative has a higher binding affinity for p32 G-quadruplex than duplex. Further circular dichroism and nuclear magnetic resonance studies indicate that the phenanthroline derivative can regulate p32 G-quadruplex conformation. Real time polymerase chain reaction and luciferase assays show that the phenanthroline derivative has down-modulated Bcl-2 transcription activity in a concentration-dependent manner. However, no such effect was observed when p32 G-quadruplex was denatured through base mutation. CONCLUSION: The newly identified G-quadruplex located in the P1 promoter of Bcl-2 oncogene is intimately related with Bcl-2 transcription activity, which may be a promising anticancer therapeutic target. GENERAL SIGNIFICANCE: The newly identified G-quadruplex in the Bcl-2 P1 promoter may be a novel anticancer therapeutic target.


Assuntos
Quadruplex G , Regulação Neoplásica da Expressão Gênica/efeitos da radiação , Regiões Promotoras Genéticas , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Transcrição Genética/efeitos da radiação , Raios Ultravioleta , Linhagem Celular Tumoral , Humanos , Proteínas Proto-Oncogênicas c-bcl-2/genética
9.
Acta Biochim Biophys Sin (Shanghai) ; 46(5): 368-76, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24681881

RESUMO

The RecFOR DNA repair pathway is one of the major RecA-dependent recombinatorial repair pathways in bacteria and plays an important role in double-strand breaks repair. RecO, one of the major recombination mediator proteins in the RecFOR pathway, has been shown to assist RecA loading onto single-stranded binding protein (SSB) coated single-stranded DNA (ssDNA). However, it has not been characterized whether the protein-protein interaction between RecO and SSB contributes to that process in vivo. Here, we identified the residue arginine-121 of Deinococcus radiodurans RecO (drRecO-R121) as the key residue for RecO-SSB interaction. The substitution of drRecO-R121 with alanine greatly abolished the binding of RecO to SSB but not the binding to RecR. Meanwhile, SSB-coated ssDNA annealing activity was also compromised by the mutation of the residue of drRecO. However, the drRecO-R121A strain showed only modest sensitivity to DNA damaging agents. Taking these data together, arginine-121 of drRecO is the key residue for SSB-RecO interaction, which may not play a vital role in the SSB displacement and RecA loading process of RecFOR DNA repair pathway in vivo.


Assuntos
Proteínas de Bactérias/fisiologia , Reparo do DNA , Deinococcus/fisiologia , Sequência de Bases , Primers do DNA , Ensaio de Desvio de Mobilidade Eletroforética
10.
Analyst ; 139(3): 581-4, 2014 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-24325001

RESUMO

A colorimetric and fluorometric dual-modal supramolecular chemosensor has been fabricated by using the H- and J-aggregates of a cyanine dye, which has been successfully applied to detect human serum albumin (HSA) in urine with high specificity.


Assuntos
Técnicas de Química Analítica/instrumentação , Fluorometria , Albumina Sérica/análise , Colorimetria , Humanos , Modelos Moleculares , Conformação Proteica , Albumina Sérica/química
11.
J Photochem Photobiol B ; 128: 115-21, 2013 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-24103782

RESUMO

Reactive oxygen species scavenging effect of Pleioblastus kongosanensis f. aureostriatus leaf extract against O2(-), OH and H2O2 were investigated by chemiluminescence methods in vitro. Bamboo grass leaves were extracted with 70% ethanol solution and sequentially partitioned with solvents in an order of increasing polarity. Among fractions of different polarity, BuOH and EtOAc fractions showed powerful scavenging activities than others, and showed better scavenging ability on OH than that of O2(-)and H2O2, with IC50 of 0.55 µg/mL and 0.60 µg/mL, respectively. Both OH-induced DNA damage model by chemiluminescence assay and plasmid pUC18 double-strand break model by agarose gel electrophoresis showed that BuOH and EtOAc fractions had remarkable concentration-dependent prevention effect on the OH-induced damage of DNA attribute to their good scavenging effects on ROS. Results from the compositional analysis of different fractions indicate that the flavonoids in the Pleioblastus kongosanensis f. aureostriatus leaf may be responsible for its ROS scavenging activity and DNA damage prevention ability.


Assuntos
Dano ao DNA/efeitos dos fármacos , Depuradores de Radicais Livres/química , Extratos Vegetais/farmacologia , Sasa/química , Acetoacetatos/química , Etanol/química , Flavonoides/análise , Depuradores de Radicais Livres/farmacologia , Medições Luminescentes , Extratos Vegetais/química , Folhas de Planta/química , Folhas de Planta/metabolismo , Polifenóis/análise , Espécies Reativas de Oxigênio/química , Sasa/metabolismo , Terpenos/análise
12.
J Nutr Sci Vitaminol (Tokyo) ; 59(4): 336-42, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24064734

RESUMO

Indocalamus latifolius (Keng) McClure leaf is a popular food material in East Asia due to its antioxidant and anticorrosive activities. To utilize it more effectively, we investigated the discrepancy of antioxidant activities and active compound content in Indocalamus latifolius leaf along with the altitude change. Total flavonoids, phenolics, titerpenoids and eight characteristic active constituents, i.e, orientin, isoorientin, vitexin, homovitexin, p-coumaric acid, chlorogenic acid, caffeic acid, and ferulic acid, were determined by UV-spectrophotometer and synchronous RP-HPLC, respectively. Antioxidant activity was measured using DPPH and FRAP methods. Our data showed that the content of TP and TF, DPPH radical scavenging ability and ferric reduction power of Indocalamus latifolius leaf changed as altitude altered, with the trends of decreasing gradually when lower than 700 m and then increasing to 1,000 m. Chlorogenic acid and orientin were the main characteristic compounds in Indocalamus latifolius leaf and were also affected by altitude. Our result indicated that higher altitude with an adverse environment is conducive to secondary metabolite accumulation for Indocalamus latifolius. It would provide a theoretical basis to regulate the leaf collection conditions in the industrial use of Indocalamus latifolius leaf.


Assuntos
Antioxidantes/farmacologia , Ácido Clorogênico/farmacologia , Ecossistema , Flavonoides/farmacologia , Glucosídeos/farmacologia , Extratos Vegetais/farmacologia , Folhas de Planta/química , Poaceae/química , Antioxidantes/análise , Apigenina/análise , Apigenina/farmacologia , Ásia , Compostos de Bifenilo/metabolismo , Ácidos Cafeicos/análise , Ácidos Cafeicos/farmacologia , Ácido Clorogênico/análise , Ácidos Cumáricos/análise , Ácidos Cumáricos/farmacologia , Dieta , Compostos Férricos/metabolismo , Flavonoides/análise , Glucosídeos/análise , Picratos/metabolismo , Extratos Vegetais/química , Polifenóis/análise , Polifenóis/farmacologia , Metabolismo Secundário , Triterpenos/análise , Triterpenos/farmacologia
13.
Chem Commun (Camb) ; 49(40): 4510-2, 2013 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-23577345

RESUMO

A G-quadruplex is identified which can exhibit two different motifs, respectively, corresponding to Na(+) and K(+). The relative amount of each motif is related to the Na(+)/K(+) ratio. Based on selective recognition of the G-quadruplex motifs by a cyanine dye aggregate, a method for both colorimetric and quantitative measurements of Na(+)/K(+) ratios is constructed.


Assuntos
Quadruplex G , Potássio/química , Sódio/química , Carbocianinas/química , Colorimetria , Corantes Fluorescentes/química , Estrutura Molecular
14.
Analyst ; 137(24): 5713-5, 2012 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-23108173

RESUMO

A supramolecular probe is designed for visual detection of potassium based on a novel cyanine dye aggregate recognizing the motif transition of telomeric G-quadruplexes under the Na(+) background. The practical application for colorimetric measurement of urine potassium has been tested.


Assuntos
Carbocianinas/química , Colorimetria/métodos , Corantes/química , Quadruplex G , Motivos de Nucleotídeos , Potássio/análise , Humanos , Potássio/urina , Telômero/genética
15.
PLoS One ; 7(4): e35057, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22523570

RESUMO

The high intracellular Mn/Fe ratio observed within the bacteria Deinococcus radiodurans may contribute to its remarkable resistance to environmental stresses. We isolated DR2539, a novel regulator of intracellular Mn/Fe homeostasis in D. radiodurans. Electrophoretic gel mobility shift assays (EMSAs) revealed that DR2539 binds specifically to the promoter of the manganese acquisition transporter (MntH) gene, and that DR0865, the only Fur homologue in D. radiodurans, cannot bind to the promoter of mntH, but it can bind to the promoter of another manganese acquisition transporter, MntABC. ß-galactosidase expression analysis indicated that DR2539 acts as a manganese- and iron-dependent transcriptional repressor. Further sequence alignment analysis revealed that DR2539 has evolved some special characteristics. Site-directed mutagenesis suggested that His98 plays an important role in the activities of DR2539, and further protein-DNA binding activity assays showed that the activity of H98Y mutants decreased dramatically relative to wild type DR2539. Our study suggests that D. radiodurans has evolved a very efficient manganese regulation mechanism that involves its high intracellular Mn/Fe ratio and permits resistance to extreme conditions.


Assuntos
Proteínas de Bactérias/genética , Proteínas de Transporte de Cátions/genética , Deinococcus/metabolismo , Proteínas Repressoras/fisiologia , Sequência de Aminoácidos , Proteínas de Bactérias/biossíntese , Proteínas de Transporte de Cátions/biossíntese , Deinococcus/genética , Compostos Ferrosos/metabolismo , Regulação Bacteriana da Expressão Gênica , Manganês/metabolismo , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Alinhamento de Sequência
16.
Int J Mol Sci ; 13(2): 2249-62, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22408451

RESUMO

Sasa argenteastriatus, with abundant active compounds and high antioxidant activity in leaves, is a new leafy bamboo grove suitable for exploitation. To utilize it more effectively and scientifically, we investigate the seasonal variations of antioxidant composition in its leaves and antioxidant activity. The leaves of Sasa argenteastriatus were collected on the 5th day of each month in three same-sized sample plots from May 2009 to May 2011. The total flavonoids (TF): phenolics (TP) and triterpenoid (TT) of bamboo leaves were extracted and the contents analyzed by UV-spectrophotometer. Our data showed that all exhibited variations with the changing seasons, with the highest levels appearing in November to March. Antioxidant activity was measured using DPPH and FRAP methods. The highest antioxidant activity appeared in December with the lowest in May. Correlation analyses demonstrated that TP and TF exhibited high correlation with bamboo antioxidant activity. Eight bamboo characteristic compounds (orientin, isoorientin, vitexin, homovitexin and p-coumaric acid, chlorogenic acid, caffeic acid, ferulic acid) were determined by RP-HPLC synchronously. We found that chlorogenic acid, isoorientin and vitexin are the main compounds in Sasa argenteastriatus leaves and the content of isovitexin and chlorogenic acid showed a similar seasonal variation with the TF, TP and TT. Our results suggested that the optimum season for harvesting Sasa argenteastriatus leaves is between autumn and winter.


Assuntos
Antioxidantes/análise , Extratos Vegetais/química , Folhas de Planta/química , Sasa/química , Estações do Ano , Antioxidantes/metabolismo , Apigenina/análise , Apigenina/metabolismo , Ácidos Cafeicos/análise , Ácidos Cafeicos/metabolismo , Cromatografia Líquida de Alta Pressão , Ácidos Cumáricos/análise , Ácidos Cumáricos/metabolismo , Flavonoides/análise , Flavonoides/metabolismo , Glucosídeos/análise , Glucosídeos/metabolismo , Fenóis/análise , Fenóis/metabolismo , Folhas de Planta/metabolismo , Propionatos , Sasa/metabolismo , Triterpenos/análise , Triterpenos/metabolismo
17.
DNA Repair (Amst) ; 11(4): 349-56, 2012 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-22301370

RESUMO

The single-stranded DNA-specific nuclease RecJ is found in most bacteria where it is involved in the RecFOR double-stranded break (DSBs) repair pathway. DSBs repair mainly occurs via the RecFOR pathway in Deinococcus radiodurans, a well-known radiation-resistant bacterium. A recJ null mutant was constructed to investigate the role of recJ in D. radiodurans. recJ inactivation caused growth defects and sensitivity to high temperatures. However, the radiation resistance of the recJ mutant was only moderately decreased. The full-length D. radiodurans RecJ (DrRecJ) protein was expressed and purified to further characterize its biochemical properties. DrRecJ possessed a Mn(2+) concentration-dependent nuclease activity where the optimal Mn(2+) concentration was 0.1mM. DrRecJ had a similar activity profile after adding 10mM Mg(2+) to reactions with different Mn(2+) concentrations, indicating that Mn(2+) is a RecJ regulator. Escherichia coli RecJ has no activity on 5' ssDNA tails shorter than 6-nt, but DrRecJ could effectively degrade DNA with a 4-nt 5' ssDNA tail, suggesting that DrRecJ may have a wider range of DNA substrates. Moreover, SSB in D. radiodurans stimulated the DrRecJ exonuclease activity, whereas DdrB inhibited it and provided protection to ssDNA. Overall, our results indicate that recJ is a nonessential gene in D. radiodurans and that the activity of DrRecJ is regulated by Mn(2+) and SSB-DdrB.


Assuntos
Proteínas de Bactérias/metabolismo , Deinococcus/enzimologia , Exodesoxirribonucleases/metabolismo , Proteínas de Bactérias/genética , Proliferação de Células/efeitos dos fármacos , Proliferação de Células/efeitos da radiação , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/genética , Sobrevivência Celular/efeitos da radiação , DNA de Cadeia Simples/metabolismo , Proteínas de Ligação a DNA/metabolismo , Deinococcus/citologia , Deinococcus/genética , Deinococcus/efeitos da radiação , Ativação Enzimática/efeitos dos fármacos , Ativação Enzimática/efeitos da radiação , Exodesoxirribonucleases/deficiência , Exodesoxirribonucleases/genética , Técnicas de Inativação de Genes , Manganês/farmacologia , Tolerância a Radiação/genética
18.
Analyst ; 137(4): 862-7, 2012 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-22223064

RESUMO

Recognition of different human telomeric G-quadruplex structures has been a very important task for developing anti-cancer drug design. However, it also is a very challenging question since multiple conformational isomers of telomeric G-quadruplexes coexist under some conditions. Here, three different conformations including parallel, antiparallel, and mixed-type telomeric G-quadruplex structures have been well recognized by quinacrine (QNA) through monitoring its absorption, fluorescence, and fluorescence lifetime spectra. The multiple structures of H22 G-quadruplexes under physiological K(+) conditions could also be easily determined to coexist as mixed-type and antiparallel G-quadruplexes. The recognition mechanism based on the different binding affinity and binding sites has been further elucidated by association with the nuclear magnetic resonance (NMR) results.


Assuntos
Quadruplex G , Ressonância Magnética Nuclear Biomolecular/métodos , Quinacrina , Telômero/química , Sítios de Ligação , Desenho de Fármacos , Humanos , Modelos Moleculares , Conformação Molecular , Conformação de Ácido Nucleico , Telomerase/antagonistas & inibidores , Telomerase/metabolismo
19.
J Phys Chem Lett ; 3(1): 131-5, 2012 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-26701419

RESUMO

Calixaromatics have attracted much attention on molecular recognition owing to their flexible conformations, cavity structures, versatile recognition properties, and functions. However, conformational control of calixaromatics is still a challenging topic in the field of calixaromatics. Therefore, we explore the possibility to control the chirality of achiral calixaromatics, methylazacalix[6]pyridine (abbreviated as MACP6), by templating of DNA. We have found that MACP6 with opposite chirality can be achieved by controlling the secondary structure of bcl-2 2345 DNA. Furthermore, MACP6 with different chirality has been used to recognize fullerene derivatives in aqueous solution. Our results have provided a possible approach to construct chiral calixaromatics.

20.
DNA Repair (Amst) ; 11(2): 139-45, 2012 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-22051194

RESUMO

The extremely radioresistant bacterium Deinococcus radiodurans possesses a rapid and efficient but poorly known DNA damage response mechanism that mobilizes one-third of its genome to survive lethal radiation damage. Deinococcal PprI serves as a general switch to regulate the expression of dozens of proteins from different pathways after radiation, including the DNA repair proteins RecA, PprA and SSB. However, the underlying mechanism is poorly understood. In this study, we analyzed the dynamic alteration in global transcriptional profiles in wildtype and pprI mutant strains by combining microarrays and time-course sampling. We found that PprI up-regulated transcription of at least 210 genes after radiation, including 21 DNA repair and replication-related genes. We purified PprI and a helix-turn-helix (HTH) domain mutant and found that PprI specifically bound to the promoters of recA and pprA in vitro but did not bind nonspecific double-strand DNA. Chromatin immunoprecipitation (ChIP) assays confirmed that PprI specifically interacted with the promoter DNA of recA and pprA after radiation. Finally, we showed that a DNA-binding activity-deficient pprI mutant only partially restored resistance of the pprI mutant strain to γ radiation, UV radiation, and mitomycin C. Taken together, these results indicate that DNA-binding activity is essential for PprI to program the DNA repair process and cellular survival of D. radiodurans in response to radiation damage.


Assuntos
Proteínas de Bactérias/metabolismo , Dano ao DNA , DNA Bacteriano/genética , DNA Bacteriano/metabolismo , Deinococcus/genética , Deinococcus/efeitos da radiação , Proteínas de Bactérias/química , Deinococcus/efeitos dos fármacos , Deinococcus/metabolismo , Análise de Sequência com Séries de Oligonucleotídeos , Regiões Promotoras Genéticas/efeitos dos fármacos , Regiões Promotoras Genéticas/efeitos da radiação , Ligação Proteica/efeitos dos fármacos , Ligação Proteica/efeitos da radiação , Estrutura Terciária de Proteína , Recombinases Rec A/metabolismo , Regulon/efeitos dos fármacos , Regulon/genética , Regulon/efeitos da radiação , Transcrição Genética/efeitos dos fármacos , Transcrição Genética/efeitos da radiação , Regulação para Cima/efeitos dos fármacos , Regulação para Cima/efeitos da radiação
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