RecQ is a highly conserved helicase necessary for maintaining genome stability in all organisms. Genome comparison showed that a homologue of RecQ in Deinococcus radiodurans designated as DR1289 is a member of RecQ fa...RecQ is a highly conserved helicase necessary for maintaining genome stability in all organisms. Genome comparison showed that a homologue of RecQ in Deinococcus radiodurans designated as DR1289 is a member of RecQ family with unusual domain arrangement: a helicase domain, an RecQ C-terminal domain, and surprisingly three HRDC domain repeats, whose func-tion, however, remains obscure currently. Using an insertion deletion, we discovered that the DRRecQ mutation causes an increase in gamma radiation, hydroxyurea and mitomycine C and UV sensitivity. Using the shuttle plasmid pRADK, we complemented various domains of the D. radiodurans RecQ (DRRecQ) to the mutant in vivo. Results suggested that both the helicase and helicase-and-RNase-D-C-terminal (HRDC) domains are essential for complementing several phenotypes. The complementation and biochemical function of DRRecQ variants with different domains truncated in vitro suggested that both the helicase and three HRDC domains are necessary for RecQ functions in D. radiodurans, while three HRDC domains have a synergistic effect on the whole function. Our finding leads to the hypothesis that the RecF recombination pathway is likely a primary path of double strand break repair in this well-known radioresistant organism.展开更多
To explore the survival and dose response of organism for different radiation sources is of great importance in the research of radiobiology. In this study, the survival-dose response of Deinococcus radiodurans (E.col...To explore the survival and dose response of organism for different radiation sources is of great importance in the research of radiobiology. In this study, the survival-dose response of Deinococcus radiodurans (E.coli, as the control) for ultra-violet (UV), γ-rays radiation and ion beam exposure was investigated. The shoulder type of survival curves were found for both UV and γ-ray ionizing radiation, but the saddle type of survival curves were shown for H+、 N+( 20keV and 30keV) and Ar+ beam exposure. This dose effect of the survival initially decreased with the increase in dose and then increased in the high dose range and finally decreased again in the higher dose range. Our experimental results suggest that D. radiodurans, which is considerably radio-resistant to UV and x-ray and γ-ray ionizing radiation, do not resist ion beam exposure.展开更多
Though bacteria of the radiation-resistant Deinococcus radiodurans have a high resistance to the lethal and mutagenic effects of many DNA-damaging agents, the mechanisms involved in the response of these bacteria to o...Though bacteria of the radiation-resistant Deinococcus radiodurans have a high resistance to the lethal and mutagenic effects of many DNA-damaging agents, the mechanisms involved in the response of these bacteria to oxidative stress are poorly understood. In this report, the superoxide dismutase (SOD) and catalase (CAT) activities produced by these bacteria were measured, and the change of SOD and CAT activities by 20 keV N+ beam exposure was examined. Their activities were increased by N+ beam exposure from 8x 1014 ions/cm2 to 6x1015 ions/cm2.The treatment of H2O2 and [ CHC13 +CH3 CH2OH ] and the measurement of absorption spectrum showed that the increase in SOD activity was resulted from inducible activities of MnSOD in D. radiodurans AS1.633 by N+ beam exposure . These results suggested that this bacteria possess inducible defense mechanisms against the deleterious effects of oxidization.展开更多
Objectives:This study used Deinococcus radiodurans,which is extremely resistant to oxidative damage,genotoxic chemicals,high levels of ionising and ultraviolet radiation and drying,and its Vitreoscilla haemoglobin(vgb...Objectives:This study used Deinococcus radiodurans,which is extremely resistant to oxidative damage,genotoxic chemicals,high levels of ionising and ultraviolet radiation and drying,and its Vitreoscilla haemoglobin(vgb)gene-cloned recombinant with the vgb−recombinant strain as a control.In addition to the conditions wherein bacteria have an optimum Cr(Ⅲ)biosorption capacity,the contribution of the vgb gene to the biosorption ability of the bacteria has been investigated by providing the organism with a more oxygenic environment.Methods:Bacteria were produced and metal stock solution was prepared.To determine the Cr(Ⅲ)removal capacities of wild and recombinant D.radiodurans strains,the residual metal concentration in aqueous media at the beginning and after biosorption was determined in Atomic Absorption Spectrophotometer.Some optimal conditions were created for the biosorption conditions to occur.Conclusions:The optimisation tests showed that Cr(Ⅲ)reached the highest biosorption capacity within 15 minutes at a metal concentration of 2,000 ppm,30°C,pH 5.0 and 150 rpm stirring speed in all the three bacteria.The vgb gene had no significant contribution to the biosorption capacity.展开更多
DR1709 is a predicted Mn2+ transporter in Deinococcus radiodurans(D.radiodurans). The mensuration method to evaluate protein viability with two-dimensional electrophoresis in D.radiodurans and the mutants was establis...DR1709 is a predicted Mn2+ transporter in Deinococcus radiodurans(D.radiodurans). The mensuration method to evaluate protein viability with two-dimensional electrophoresis in D.radiodurans and the mutants was established in this study. The results showed that after DR1709 was disrupted, the expressions of DR1120 (acetokinase), DR1691 (heat shock protein), DR1485 (putative lipase), DR2095 (putative c-type cytochrome) and other three hypothetical proteins (DR0124, DR0047 and DR2474) were repressed. However the expression of DR1794 (putative nosX) was induced. Phenomena above suggested that the increased radiation-sensitivity of the mutant cells may be attributed to not only the protection of gene DR1709, but also the proteins' different expressions between the wild type and the mutant might also play important roles in protecting D.radiodurans from irradiation. Although DR2095 was a homologue of c-type cytochrome, it has no realitic functions.展开更多
Though the radiation-resistant bacteria Deinococcus radiodurans (D. radiodurans) have a high resistance to the lethal and mutagenic effects of many DNA-damaging agents, the mechanisms involved in the response of these...Though the radiation-resistant bacteria Deinococcus radiodurans (D. radiodurans) have a high resistance to the lethal and mutagenic effects of many DNA-damaging agents, the mechanisms involved in the response of these bacteria to oxidative stress are poorly understood. In this report, the superoxide dismutase (SOD) and catalase (CAT) activities produced in bacteria (D.radiodurans AS1.633) and their change caused by 20 keV N+ beam exposure were examined. Results showed that the activities of the enzymes were increased in the case of N+ beam exposure from 8×1014 ions/cm2 to 6×1015 ions/cm2. In addition, the treatment of H2O2 and [CHCl3+CH3CH2OH] and the measurement of absorption spectrum showed that the increase of whole SOD activity resulted from inducible activities of Mn-SOD in (a sub^type) D.radiodurans AS1.633. These results suggested that these bacteria possess inducible defense mechanisms against the deleterious effects of oxidization.展开更多
基金Project supported by the National Basic Research Program (973) of China (No. 2004CB19604), Distinguished Young Scientist of China (No. 30425038), and the National Natural Science Foundation of China (No. 30330020)
文摘RecQ is a highly conserved helicase necessary for maintaining genome stability in all organisms. Genome comparison showed that a homologue of RecQ in Deinococcus radiodurans designated as DR1289 is a member of RecQ family with unusual domain arrangement: a helicase domain, an RecQ C-terminal domain, and surprisingly three HRDC domain repeats, whose func-tion, however, remains obscure currently. Using an insertion deletion, we discovered that the DRRecQ mutation causes an increase in gamma radiation, hydroxyurea and mitomycine C and UV sensitivity. Using the shuttle plasmid pRADK, we complemented various domains of the D. radiodurans RecQ (DRRecQ) to the mutant in vivo. Results suggested that both the helicase and helicase-and-RNase-D-C-terminal (HRDC) domains are essential for complementing several phenotypes. The complementation and biochemical function of DRRecQ variants with different domains truncated in vitro suggested that both the helicase and three HRDC domains are necessary for RecQ functions in D. radiodurans, while three HRDC domains have a synergistic effect on the whole function. Our finding leads to the hypothesis that the RecF recombination pathway is likely a primary path of double strand break repair in this well-known radioresistant organism.
基金the National Natural Science Foundation of China! No.196O5005)
文摘To explore the survival and dose response of organism for different radiation sources is of great importance in the research of radiobiology. In this study, the survival-dose response of Deinococcus radiodurans (E.coli, as the control) for ultra-violet (UV), γ-rays radiation and ion beam exposure was investigated. The shoulder type of survival curves were found for both UV and γ-ray ionizing radiation, but the saddle type of survival curves were shown for H+、 N+( 20keV and 30keV) and Ar+ beam exposure. This dose effect of the survival initially decreased with the increase in dose and then increased in the high dose range and finally decreased again in the higher dose range. Our experimental results suggest that D. radiodurans, which is considerably radio-resistant to UV and x-ray and γ-ray ionizing radiation, do not resist ion beam exposure.
基金This work was supported by the National Nature Science Foundation of China! No.19605005
文摘Though bacteria of the radiation-resistant Deinococcus radiodurans have a high resistance to the lethal and mutagenic effects of many DNA-damaging agents, the mechanisms involved in the response of these bacteria to oxidative stress are poorly understood. In this report, the superoxide dismutase (SOD) and catalase (CAT) activities produced by these bacteria were measured, and the change of SOD and CAT activities by 20 keV N+ beam exposure was examined. Their activities were increased by N+ beam exposure from 8x 1014 ions/cm2 to 6x1015 ions/cm2.The treatment of H2O2 and [ CHC13 +CH3 CH2OH ] and the measurement of absorption spectrum showed that the increase in SOD activity was resulted from inducible activities of MnSOD in D. radiodurans AS1.633 by N+ beam exposure . These results suggested that this bacteria possess inducible defense mechanisms against the deleterious effects of oxidization.
基金This study was supported by Inonu University Scientific Research Projects Coordination Unit(project number:2012-192).
文摘Objectives:This study used Deinococcus radiodurans,which is extremely resistant to oxidative damage,genotoxic chemicals,high levels of ionising and ultraviolet radiation and drying,and its Vitreoscilla haemoglobin(vgb)gene-cloned recombinant with the vgb−recombinant strain as a control.In addition to the conditions wherein bacteria have an optimum Cr(Ⅲ)biosorption capacity,the contribution of the vgb gene to the biosorption ability of the bacteria has been investigated by providing the organism with a more oxygenic environment.Methods:Bacteria were produced and metal stock solution was prepared.To determine the Cr(Ⅲ)removal capacities of wild and recombinant D.radiodurans strains,the residual metal concentration in aqueous media at the beginning and after biosorption was determined in Atomic Absorption Spectrophotometer.Some optimal conditions were created for the biosorption conditions to occur.Conclusions:The optimisation tests showed that Cr(Ⅲ)reached the highest biosorption capacity within 15 minutes at a metal concentration of 2,000 ppm,30°C,pH 5.0 and 150 rpm stirring speed in all the three bacteria.The vgb gene had no significant contribution to the biosorption capacity.
基金Supported by National Project 973 (No. 2004CB719604)
文摘DR1709 is a predicted Mn2+ transporter in Deinococcus radiodurans(D.radiodurans). The mensuration method to evaluate protein viability with two-dimensional electrophoresis in D.radiodurans and the mutants was established in this study. The results showed that after DR1709 was disrupted, the expressions of DR1120 (acetokinase), DR1691 (heat shock protein), DR1485 (putative lipase), DR2095 (putative c-type cytochrome) and other three hypothetical proteins (DR0124, DR0047 and DR2474) were repressed. However the expression of DR1794 (putative nosX) was induced. Phenomena above suggested that the increased radiation-sensitivity of the mutant cells may be attributed to not only the protection of gene DR1709, but also the proteins' different expressions between the wild type and the mutant might also play important roles in protecting D.radiodurans from irradiation. Although DR2095 was a homologue of c-type cytochrome, it has no realitic functions.
基金Supported by the National Natural Science Foundation of China (No. 19605005)
文摘Though the radiation-resistant bacteria Deinococcus radiodurans (D. radiodurans) have a high resistance to the lethal and mutagenic effects of many DNA-damaging agents, the mechanisms involved in the response of these bacteria to oxidative stress are poorly understood. In this report, the superoxide dismutase (SOD) and catalase (CAT) activities produced in bacteria (D.radiodurans AS1.633) and their change caused by 20 keV N+ beam exposure were examined. Results showed that the activities of the enzymes were increased in the case of N+ beam exposure from 8×1014 ions/cm2 to 6×1015 ions/cm2. In addition, the treatment of H2O2 and [CHCl3+CH3CH2OH] and the measurement of absorption spectrum showed that the increase of whole SOD activity resulted from inducible activities of Mn-SOD in (a sub^type) D.radiodurans AS1.633. These results suggested that these bacteria possess inducible defense mechanisms against the deleterious effects of oxidization.
