RESUMO
Bacteria under stress increase the proportion of dormant cells to ensure their survival. Cold and osmotic stress are similar, because in both the availability of water is reduced. Glycine betaine (GB) is one of the most common osmoprotectants in bacteria and possesses cryoprotectant properties. Our aim was to determine whether GB modifies the proportion of dormant Deinococcus sp. UDEC-P1 and Psychrobacter sp. UDEC-A5 cells exposed to osmotic stress. Both bacterial strains were incubated in the presence of up to 1 M NaCl with or without GB. Active and dormant cells were evaluated by both spectrophotometric and flow cytometry analysis. Without GB, Deinococcus sp. UDEC-P1 grew in the presence of 0.05 M NaCl, but with 5 mM GB grew at 0.1 M NaCl. Psychrobacter sp. UDEC-A5 grew in the presence of up to 0.25 M NaCl, but with 5 mM GB grew at 0.5 M NaCl. Under osmotic stress, the proportion of dormant cells of Deinococcus sp. UDEC-P1 and Psychrobacter sp. UDEC-A5 increased significantly (about eightfold and fivefold, respectively). The addition of GB (5 mM) exerted a different effect on the two strains, since it avoided the entrance into the dormancy of Psychrobacter sp. UDEC-A5 cells, but not of Deinococcus sp. UDEC-P1 cells. Our results suggest that the effect of GB on bacterial metabolism is strain dependent. For bacteria in which GB avoids dormancy, such as Psychrobacter sp. UDEC-A5, it could be a "double-edged sword" by reducing the "seed bank" available to recover the active population when favorable conditions return.
Assuntos
Betaína/metabolismo , Deinococcus/crescimento & desenvolvimento , Psychrobacter/crescimento & desenvolvimento , Proteínas de Bactérias/metabolismo , Deinococcus/fisiologia , Pressão Osmótica , Psychrobacter/fisiologia , Cloreto de Sódio/metabolismo , Estresse FisiológicoRESUMO
Deinococcus radiodurans (DR) is an extremophile that is well known for its resistance to radiation, oxidants and desiccation. The gene dr1790 of D. radiodurans was predicted to encode a yellow-related protein. The primary objective of the present study was to characterize the biological function of the DR1790 protein, which is a member of the ancient yellow/major royal jelly (MRJ) protein family, in prokaryotes. Fluorescence labeling demonstrated that the yellow-related protein encoded by dr1790 is a membrane protein. The deletion of the dr1790 gene decreased the cell growth rate and sensitivity to hydrogen peroxide and radiation and increased the membrane permeability of D. radiodurans. Transcript profiling by microarray and RT-PCR analyses of the dr1790 deletion mutant suggested that some genes that are involved in protein secretion and transport were strongly suppressed, while other genes that are involved in protein quality control, such as chaperones and proteases, were induced. In addition, the expression of genes with predicted functions that are involved in antioxidant systems, electron transport, and energy metabolism was significantly altered through the disruption of dr1790. Moreover, the results of proteomic analyses using 2-DE and MS also demonstrated that DR1790 contributed to D. radiodurans survival. Taken together, these results indicate that the DR1790 protein from the ancient yellow protein family plays a pleiotropic role in the survival of prokaryotic cells and contributes to the extraordinary resistance of D. radiodurans against oxidative and radiation stresses.
Assuntos
Deinococcus/genética , Genes Bacterianos , Pleiotropia Genética , Mutagênese Insercional , Proteínas de Bactérias/genética , Membrana Celular/fisiologia , Deinococcus/efeitos dos fármacos , Deinococcus/crescimento & desenvolvimento , Deinococcus/efeitos da radiação , Deleção de Genes , Perfilação da Expressão Gênica , Teste de Complementação Genética , Peróxido de Hidrogênio/toxicidade , Proteínas de Membrana/genética , Análise em Microsséries , Viabilidade Microbiana/efeitos dos fármacos , Viabilidade Microbiana/efeitos da radiação , Permeabilidade , Radiação Ionizante , Reação em Cadeia da Polimerase em Tempo RealRESUMO
Deinococcus radiodurans (DR) is an extremophile that is well known for its resistance to radiation, oxidants and desiccation. The gene dr1790 of D. radiodurans was predicted to encode a yellow-related protein. The primary objective of the present study was to characterize the biological function of the DR1790 protein, which is a member of the ancient yellow/major royal jelly (MRJ) protein family, in prokaryotes. Fluorescence labeling demonstrated that the yellow-related protein encoded by dr1790 is a membrane protein. The deletion of the dr1790 gene decreased the cell growth rate and sensitivity to hydrogen peroxide and radiation and increased the membrane permeability of D. radiodurans. Transcript profiling by microarray and RT-PCR analyses of the dr1790 deletion mutant suggested that some genes that are involved in protein secretion and transport were strongly suppressed, while other genes that are involved in protein quality control, such as chaperones and proteases, were induced. In addition, the expression of genes with predicted functions that are involved in antioxidant systems, electron transport, and energy metabolism was significantly altered through the disruption of dr1790. Moreover, the results of proteomic analyses using 2-DE and MS also demonstrated that DR1790 contributed to D. radiodurans survival. Taken together, these results indicate that the DR1790 protein from the ancient yellow protein family plays a pleiotropic role in the survival of prokaryotic cells and contributes to the extraordinary resistance of D. radiodurans against oxidative and radiation stresses.
Assuntos
Deinococcus/genética , Genes Bacterianos , Pleiotropia Genética , Mutagênese Insercional , Proteínas de Bactérias/genética , Membrana Celular/fisiologia , Deinococcus/efeitos dos fármacos , Deinococcus/crescimento & desenvolvimento , Deinococcus/efeitos da radiação , Deleção de Genes , Perfilação da Expressão Gênica , Teste de Complementação Genética , Peróxido de Hidrogênio/toxicidade , Análise em Microsséries , Proteínas de Membrana/genética , Viabilidade Microbiana/efeitos dos fármacos , Viabilidade Microbiana/efeitos da radiação , Permeabilidade , Radiação Ionizante , Reação em Cadeia da Polimerase em Tempo RealRESUMO
Deinococcus radiodurans (DR) is an extremophile that is well known for its resistance to radiation, oxidants and desiccation. The gene dr1790 of D. radiodurans was predicted to encode a yellow-related protein. The primary objective of the present study was to characterize the biological function of the DR1790 protein, which is a member of the ancient yellow/major royal jelly (MRJ) protein family, in prokaryotes. Fluorescence labeling demonstrated that the yellow-related protein encoded by dr1790 is a membrane protein. The deletion of the dr1790 gene decreased the cell growth rate and sensitivity to hydrogen peroxide and radiation and increased the membrane permeability of D. radiodurans. Transcript profiling by microarray and RT-PCR analyses of the dr1790 deletion mutant suggested that some genes that are involved in protein secretion and transport were strongly suppressed, while other genes that are involved in protein quality control, such as chaperones and proteases, were induced. In addition, the expression of genes with predicted functions that are involved in antioxidant systems, electron transport, and energy metabolism was significantly altered through the disruption of dr1790. Moreover, the results of proteomic analyses using 2-DE and MS also demonstrated that DR1790 contributed to D. radiodurans survival. Taken together, these results indicate that the DR1790 protein from the ancient yellow protein family plays a pleiotropic role in the survival of prokaryotic cells and contributes to the extraordinary resistance of D. radiodurans against oxidative and radiation stresses.(AU)
Assuntos
Deinococcus/genética , Genes Bacterianos , Pleiotropia Genética , Mutagênese Insercional , Proteínas de Bactérias/genética , Membrana Celular/fisiologia , Deinococcus , Deinococcus/crescimento & desenvolvimento , Deinococcus/efeitos da radiação , Deleção de Genes , Perfilação da Expressão Gênica , Teste de Complementação Genética , Peróxido de Hidrogênio/toxicidade , Proteínas de Membrana/genética , Análise em Microsséries , Viabilidade Microbiana , Viabilidade Microbiana/efeitos da radiação , Permeabilidade , Radiação Ionizante , Reação em Cadeia da Polimerase em Tempo RealRESUMO
Dormancy is characterized by low metabolism and absence of protein synthesis and cellular division enabling bacterial cells to survive under stress. The aim was to determine if carbon starvation and low temperature are factors that modify the proportion of dormant/active cells in Deinococcus sp. UDEC-P1. By flow cytometry, RedoxSensor Green (RSG) was used to quantify metabolic activity and Propidium Iodide (PI) to evaluate membrane integrity in order to determine the percentage of dormant cells. Cell size and morphology were determined using scanning electronic microscopy. Under carbon starvation at 30°C, Deinococcus sp. UDEC-P1 increased its proportion of dormant cells from 0.1% to 20%, decreased the count of culturable cells and average cell volume decreased 7.1 times. At 4°C, however, the proportion of dormant cells increased only to 6%, without a change in the count of culturable cells and an average cellular volume decrease of 4.1 times and 3% of the dormant cells were able to be awakened. Results indicate a greater proportion of dormant Deinococcus sp. UDEC-P1 cells at 30ºC and it suggests that carbon starvation is more deleterious condition at 30ºC than 4ºC. For this reason Deinococcus sp. UDEC-P1 cells are more likely to enter into dormancy at higher temperature as a strategy to survive.