We describe and discuss the most recent findings on the activity and function of the oligomeric AAA+ chaperone ClpB from the Hsp100 protein family in pathogenic microorganisms. Pathogens are exposed to significant str...We describe and discuss the most recent findings on the activity and function of the oligomeric AAA+ chaperone ClpB from the Hsp100 protein family in pathogenic microorganisms. Pathogens are exposed to significant stress during infection of the host cells, frequently resulting in protein aggregation. The fact that ClpB is usually up-regulated in pathogens together with its immune reactivity suggests that ClpB acting as a protein disaggregase may be important for pathogen invasion and virulence. However, the specific function of ClpB in pathogenicity is still unclear. Since it is known that ClpB does not exist in mammals, it may serve as a potential target for the development of an effective therapy against several major bacterial diseases that do not respond to conventional antibiotics.展开更多
This study examined the anti-hepatitis B virus （HBV） effect of wild-type （WT） vacuolar protein sorting 4B （VPS4B） and its dominant negative （DN） mutant VPS4B-K180Q in vivo in order to further explore the relat...This study examined the anti-hepatitis B virus （HBV） effect of wild-type （WT） vacuolar protein sorting 4B （VPS4B） and its dominant negative （DN） mutant VPS4B-K180Q in vivo in order to further explore the relationship between HBV and the host cellular factor VPS4. VPS4B gene was amplified from Huh7 cells by RT-PCR and cloned into the eukaryotic expression vector pXF3H. Then, the VPS4B plasmid and the VPS4B-K180Q mutation plasmid were constructed by using the overlap extension PCR site-directed mutagenesis technique. VPS4B and HBV vectors were co-delivered into mice by the hydrodynamic tail-vein injection to establish HBV vector-based models. Quantities of HBsAg and HBeAg in the mouse sera were determined by ElectroChemiLuminescence （ECL）. HBV DNA in sera was measured by real-time quantitative PCR. Southern blot analysis was used to assay the intracellular HBV nuclear capsid-related DNA, real-time quantitative PCR to detect the HBV-related mRNA and immunohistochemical staining to observe the HBcAg expression in the mouse liver tissues. Our results showed that VPS4B and its mutant VPS4B-K180Q could decrease the levels of serum HBsAg, HBeAg and HBV-DNA. In addition, the HBV DNA replication and the mRNA level of HBV in the liver tissues of treated mice could be suppressed by VPS4B and VPS4B-K180Q. It was also found that VPS4B and VPS4B-K180Q had an ability to inhibit core antigen expression in the infected mouse liver. Furthermore, the anti-HBV effect of mutant VPS4B-K180Q was more potent than that of wild-type VPS4B. Taken together, it was concluded that VPS4B and its DN mutant VPS4B-K180Q have anti-HBV effect in vivo, which helps develop molecular therapeutic strategies for HBV infection.展开更多
Targeted protein degradation through the CDC48 unfoldase enables the maintenance and rapid adaptation of proteomes across eukaryotes.However,the substantial differences among animals,fungi,and plants presumably drove ...Targeted protein degradation through the CDC48 unfoldase enables the maintenance and rapid adaptation of proteomes across eukaryotes.However,the substantial differences among animals,fungi,and plants presumably drove extensive adaptation of CDC48-mediated degradation.Although animal and fungal CDC48 systems have shown structural and functional preservation,comparable analysis has been lacking for plants.We determined the structural and functional characteristics of Arabidopsis thaliana CDC48A in multiple states and in complex with the target-identifying cofactors UFD1 and NPL4.Our analysis revealed several features that distinguish AtCDC48A from its animal and yeast counterparts despite 80%sequence identity.Key findings include that AtCDC48A exhibits distinct domain dynamics and engages AtNPL4 in a unique manner.Moreover,AtNPL4 and AtUFD1 do not form an obligate heterodimer;instead,AtNPL4 can independently bind to AtCDC48A and mediate target degradation,although their combined action is synergistic.An evolutionary analysis indicates that these Arabidopsis features are conserved across plants and represent the ancestral state of eukaryotic CDC48 systems.Collectively,our findings suggest that plant CDC48 retains a more modular and combinatorial mode of cofactor usage,highlighting a specific adaptation of targeted protein degradation in plants.展开更多
文摘We describe and discuss the most recent findings on the activity and function of the oligomeric AAA+ chaperone ClpB from the Hsp100 protein family in pathogenic microorganisms. Pathogens are exposed to significant stress during infection of the host cells, frequently resulting in protein aggregation. The fact that ClpB is usually up-regulated in pathogens together with its immune reactivity suggests that ClpB acting as a protein disaggregase may be important for pathogen invasion and virulence. However, the specific function of ClpB in pathogenicity is still unclear. Since it is known that ClpB does not exist in mammals, it may serve as a potential target for the development of an effective therapy against several major bacterial diseases that do not respond to conventional antibiotics.
基金supported by a grant from the National Mega Research Program of China(No.2008ZX10002-011)
文摘This study examined the anti-hepatitis B virus （HBV） effect of wild-type （WT） vacuolar protein sorting 4B （VPS4B） and its dominant negative （DN） mutant VPS4B-K180Q in vivo in order to further explore the relationship between HBV and the host cellular factor VPS4. VPS4B gene was amplified from Huh7 cells by RT-PCR and cloned into the eukaryotic expression vector pXF3H. Then, the VPS4B plasmid and the VPS4B-K180Q mutation plasmid were constructed by using the overlap extension PCR site-directed mutagenesis technique. VPS4B and HBV vectors were co-delivered into mice by the hydrodynamic tail-vein injection to establish HBV vector-based models. Quantities of HBsAg and HBeAg in the mouse sera were determined by ElectroChemiLuminescence （ECL）. HBV DNA in sera was measured by real-time quantitative PCR. Southern blot analysis was used to assay the intracellular HBV nuclear capsid-related DNA, real-time quantitative PCR to detect the HBV-related mRNA and immunohistochemical staining to observe the HBcAg expression in the mouse liver tissues. Our results showed that VPS4B and its mutant VPS4B-K180Q could decrease the levels of serum HBsAg, HBeAg and HBV-DNA. In addition, the HBV DNA replication and the mRNA level of HBV in the liver tissues of treated mice could be suppressed by VPS4B and VPS4B-K180Q. It was also found that VPS4B and VPS4B-K180Q had an ability to inhibit core antigen expression in the infected mouse liver. Furthermore, the anti-HBV effect of mutant VPS4B-K180Q was more potent than that of wild-type VPS4B. Taken together, it was concluded that VPS4B and its DN mutant VPS4B-K180Q have anti-HBV effect in vivo, which helps develop molecular therapeutic strategies for HBV infection.
基金supported by the King Abdullah University of Science and Technology(KAUST)through the baseline fund to S.T.A.and the Office of Sponsored Research(OSR)under award nos.URF/1/4039-01-01 and URF/1/4080-01-01.
文摘Targeted protein degradation through the CDC48 unfoldase enables the maintenance and rapid adaptation of proteomes across eukaryotes.However,the substantial differences among animals,fungi,and plants presumably drove extensive adaptation of CDC48-mediated degradation.Although animal and fungal CDC48 systems have shown structural and functional preservation,comparable analysis has been lacking for plants.We determined the structural and functional characteristics of Arabidopsis thaliana CDC48A in multiple states and in complex with the target-identifying cofactors UFD1 and NPL4.Our analysis revealed several features that distinguish AtCDC48A from its animal and yeast counterparts despite 80%sequence identity.Key findings include that AtCDC48A exhibits distinct domain dynamics and engages AtNPL4 in a unique manner.Moreover,AtNPL4 and AtUFD1 do not form an obligate heterodimer;instead,AtNPL4 can independently bind to AtCDC48A and mediate target degradation,although their combined action is synergistic.An evolutionary analysis indicates that these Arabidopsis features are conserved across plants and represent the ancestral state of eukaryotic CDC48 systems.Collectively,our findings suggest that plant CDC48 retains a more modular and combinatorial mode of cofactor usage,highlighting a specific adaptation of targeted protein degradation in plants.
