Gastric cancer is the second most frequent cancer in the world, accounting for a large proportion of all cancer cases in Asia, Latin America, and some countries in Europe. Helicobacter pylori（H pylori） is regarded a...Gastric cancer is the second most frequent cancer in the world, accounting for a large proportion of all cancer cases in Asia, Latin America, and some countries in Europe. Helicobacter pylori（H pylori） is regarded as playing a specific role in the development of atrophic gastritis, which represents the most recognized pathway in multistep intestinal-type gastric carcinogenesis. Recent studies suggest that a combination of host genetic factors, bacterial virulence factors, and environmental and lifestyle factors determine the severity of gastric damage and the eventual clinical outcome of H pylori infection. The seminal discovery of Hpylori as the leading cause of gastric cancer should lead to effective eradication strategies. Prevention of gastric cancer requires better screening strategies to identify candidates for eradication.展开更多
Ralstonia solanacearum is an important model phytopathogenic bacterium that causes bacterial wilt disease on many plant species and leads to serious economic losses. The interactions between R. solanacearum and host p...Ralstonia solanacearum is an important model phytopathogenic bacterium that causes bacterial wilt disease on many plant species and leads to serious economic losses. The interactions between R. solanacearum and host plants have become a model system for the study of plants and pathogens interactions. This paper reviews the advances on the molecular mechanisms between R. solanacearum and hosts interaction including the formation of plant innate immunity, the suppression of plant innate immunity by this pathogen and the activation of effector-triggered immunity. Furthermore, we made a prospect on how to utilize the interaction mechanism between R. solanacearum and hosts to control the disease.展开更多
The failed attempt to express HIV-gp41 in E. coli led to the investigation of HIV-gp41 segments, which is responsible for the toxicity to E. coli cells. A series of dele-tion mutants containing different regions of gp...The failed attempt to express HIV-gp41 in E. coli led to the investigation of HIV-gp41 segments, which is responsible for the toxicity to E. coli cells. A series of dele-tion mutants containing different regions of gp41 gene were constructed and expressed in E. coli BL21(DE3) strain. After IPTG induction, the high mortality of host bacteria was ob-served in host bacteria carrying the deletion mutants of gp41 gene except for those transformed with pET-HN2; coordi-nately, the mRNA transcripts of the gp41 was rapidly de-creased; and the release of [3H]uridine increased upon in-duction. All these data suggested that GP41 protein has a cytotoxic effect on E. coli, and it is the cytotoxicity of the gp41 gene product that contributes to the high mortality when expressed in E. coli.展开更多
In nature, bacteria must sense copper and tightly regulate gene expression to evade copper toxicity. Here,we identify a new copper-responsive two-component system named DsbRS in the important human pathogen Pseudomona...In nature, bacteria must sense copper and tightly regulate gene expression to evade copper toxicity. Here,we identify a new copper-responsive two-component system named DsbRS in the important human pathogen Pseudomonas aeruginosa;in this system, DsbS is a sensor histidine kinase, and DsbR, its cognate response regulator, directly induces the transcription of genes involved in protein disulfide bond formation(Dsb)(i.e., the dsbDEG operon and dsbB). In the absence of copper, DsbS acts as a phosphatase toward DsbR, thus blocking the transcription of Dsb genes. In the presence of copper, the metal ion directly binds to the sensor domain of DsbS, and the Cys82 residue plays a critical role in this process. The copperbinding behavior appears to inhibit the phosphatase activity of DsbS, leading to the activation of DsbR.The copper resistance of the dsbRS knock-out mutant is restored by the ectopic expression of the dsbDEG operon, which is a DsbRS major target. Strikingly, cognates of the dsbRS-dsbDEG pair are widely distributed across eubacteria. In addition, a DsbR-binding site, which contains the consensus sequence 5’-TTA-N8-TTAA-3’, is detected in the promoter region of dsbDEG homologs in these species. These findings suggest that the regulation of Dsb genes by DsbRS represents a novel mechanism by which bacterial cells cope with copper stress.展开更多
文摘Gastric cancer is the second most frequent cancer in the world, accounting for a large proportion of all cancer cases in Asia, Latin America, and some countries in Europe. Helicobacter pylori（H pylori） is regarded as playing a specific role in the development of atrophic gastritis, which represents the most recognized pathway in multistep intestinal-type gastric carcinogenesis. Recent studies suggest that a combination of host genetic factors, bacterial virulence factors, and environmental and lifestyle factors determine the severity of gastric damage and the eventual clinical outcome of H pylori infection. The seminal discovery of Hpylori as the leading cause of gastric cancer should lead to effective eradication strategies. Prevention of gastric cancer requires better screening strategies to identify candidates for eradication.
基金Supported by Fundamental Research Funds for the Central Universities(110201202002)
文摘Ralstonia solanacearum is an important model phytopathogenic bacterium that causes bacterial wilt disease on many plant species and leads to serious economic losses. The interactions between R. solanacearum and host plants have become a model system for the study of plants and pathogens interactions. This paper reviews the advances on the molecular mechanisms between R. solanacearum and hosts interaction including the formation of plant innate immunity, the suppression of plant innate immunity by this pathogen and the activation of effector-triggered immunity. Furthermore, we made a prospect on how to utilize the interaction mechanism between R. solanacearum and hosts to control the disease.
文摘The failed attempt to express HIV-gp41 in E. coli led to the investigation of HIV-gp41 segments, which is responsible for the toxicity to E. coli cells. A series of dele-tion mutants containing different regions of gp41 gene were constructed and expressed in E. coli BL21(DE3) strain. After IPTG induction, the high mortality of host bacteria was ob-served in host bacteria carrying the deletion mutants of gp41 gene except for those transformed with pET-HN2; coordi-nately, the mRNA transcripts of the gp41 was rapidly de-creased; and the release of [3H]uridine increased upon in-duction. All these data suggested that GP41 protein has a cytotoxic effect on E. coli, and it is the cytotoxicity of the gp41 gene product that contributes to the high mortality when expressed in E. coli.
基金supported by the National Key R&D Program of China(2016YFA0501503)the National Mega-project for Innovative Drugs of China(2019ZX09721001-004-003)+2 种基金the National Natural Science Foundation of China(31670136 31870127 and 81861138047)the Science and Technology Commission of Shanghai Municipality(19JC1416400)the State Key Laboratory of Drug Research(SIMM2003ZZ-03).
文摘In nature, bacteria must sense copper and tightly regulate gene expression to evade copper toxicity. Here,we identify a new copper-responsive two-component system named DsbRS in the important human pathogen Pseudomonas aeruginosa;in this system, DsbS is a sensor histidine kinase, and DsbR, its cognate response regulator, directly induces the transcription of genes involved in protein disulfide bond formation(Dsb)(i.e., the dsbDEG operon and dsbB). In the absence of copper, DsbS acts as a phosphatase toward DsbR, thus blocking the transcription of Dsb genes. In the presence of copper, the metal ion directly binds to the sensor domain of DsbS, and the Cys82 residue plays a critical role in this process. The copperbinding behavior appears to inhibit the phosphatase activity of DsbS, leading to the activation of DsbR.The copper resistance of the dsbRS knock-out mutant is restored by the ectopic expression of the dsbDEG operon, which is a DsbRS major target. Strikingly, cognates of the dsbRS-dsbDEG pair are widely distributed across eubacteria. In addition, a DsbR-binding site, which contains the consensus sequence 5’-TTA-N8-TTAA-3’, is detected in the promoter region of dsbDEG homologs in these species. These findings suggest that the regulation of Dsb genes by DsbRS represents a novel mechanism by which bacterial cells cope with copper stress.
