EfeB/YcdB is a member of the dye-decolorizing peroxidase (DyP) protein family. A recent study has shown that this protein can extract iron from heme without breaking the tetrapyrrole ring. We report the crystal structure of EfeB from Escherichia coli O157 bound to heme at 1.95 Å resolution. The EfeB monomer contains two domains. The heme molecule is located in a large hydrophobic pocket in the C-terminal domain. A long loop connecting the two domains extensively interacts with the heme, which is a distinctive structural feature of EfeB homologues. A large tunnel formed by this loop and the -sheet of C-terminal domain provides a potential cofactor/substrate binding site. Biochemical data show that the production of protoporphyrin IX (PPIX) is closely related to the peroxidation activity. The mutant D235N keeps nearly the same activity of guaiacol peroxidase as the wild-type protein, whereas the corresponding mutation in the classic DyP protein family completely abolished the peroxidation activity. These results suggest that EfeB is a unique member of the DyP protein family. In addition, dramatically enhanced fluorescence excitation and emission of EfeB-PPIX was observed, implying this protein may be used as a red color fluorescence marker.
Candida albicans has been detected in root carious lesions. The current study aimed to explore the action of this fungal species on the microbial ecology and the pathogenesis of root caries. Here, by analyzing C. albicans in supragingival dental plaque collected from root carious lesions and sound root surfaces of root-caries subjects as well as caries-free individuals, we observed significantly increased colonization of C. albicans in root carious lesions. Further in vitro and animal studies showed that C. albicans colonization increased the cariogenicity of oral biofilm by altering its microbial ecology, leading to a polymicrobial biofilm with enhanced acidogenicity, and consequently exacerbated tooth demineralization and carious lesion severity. More importantly, we demonstrated that the cariogenicity-promoting activity of C. albicans was dependent on PHR2. Deletion of PHR2 restored microbial equilibrium and led to a less cariogenic biofilm as demonstrated by in vitro artificial caries model or in vivo root-caries rat model. Our data indicate the critical role of C. albicans infection in the occurrence of root caries. PHR2 is the major factor that determines the ecological impact and caries-promoting activity of C. albicans in a mixed microbial consortium.
Ferroptosis, an unusual nonapoptotic cell death caused by iron-dependent accumulation of lipid peroxide, enables flexible design of antitumor platform. Specifically, as a positive role, ferroptosis can induce immune response accompanied...
Objective: We summarized the progress of the xCELLigence real-time cell analysis (RTCA) technology application in recent years for the sake of enriching and developing the application of RTCA in the field of Chinese medicine. Background: The RTCA system is an established electronic cellular biosensor. This system uses micro-electronic biosensor technology that is confirmed for real-time, label-free, dynamic and non-offensive monitoring of cell viability, migration, growth, spreading, and proliferation. Methods: We summarized the relevant experiments and literature of RTCA technology from the principles, characteristics, applications, especially from the latest application progress. Results and conclusion: RTCA is attracting more and more attention. Now it plays an important role in drug screening, toxicology, Chinese herbal medicine and so on. It has wide application prospects in the area of modern pharmaceutical evaluation and analysis.
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