The 3C-like protease (3CL(pro)) of severe acute respiratory syndrome associated coronavirus (SARS-CoV) is vital for SARS-CoV replication and is a promising drug target. Structure based virtual screening of 308307 chemical compounds was performed using the computation tool Autodock 3.0.5 on a WISDOM Production Environment. The top 1468 ranked compounds with free binding energy ranging from -14.0 to -17.09 kcal mol(-1) were selected to check the hydrogen bond interaction with amino acid residues in the active site of 3CL(pro). Fifty-three compounds from 35 main groups were tested in an in vitro assay for inhibition of 3CL(pro) expressed by Escherichia coli. Seven of the 53 compounds were selected; their IC(50) ranged from 38.57±2.41 to 101.38±3.27 μM. Two strong 3CL(pro) inhibitors were further identified as competitive inhibitors of 3CL(pro) with K(i) values of 9.11±1.6 and 9.93±0.44 μM. Hydrophobic and hydrogen bond interactions of compound with amino acid residues in the active site of 3CL(pro) were also identified.
We have suggested an important role of the pyrH gene during the infectious process of Vibrio vulnificus. Previously, we have identified 12 genes expressed preferentially during human infections by using in vivoinduced antigen technology. Among the in vivo-expressed genes, pyrH encodes UMP kinase catalyzing UMP phosphorylation. Introduction of a deletion mutation to the pyrH gene was lethal to V. vulnificus, and an insertional mutant showed a high frequency of curing. We constructed a site-directed mutant strain (R62H/ D77N) on Arg-62 and Asp-77, both predicted to be involved in UMP binding, and characterized the R62H/D77N strain compared with the previously reported insertional mutant. We further investigated the essential role of the pyrH gene in the establishment of infection using the R62H/D77N strain. Cytotoxicity was decreased in the R62H/D77N strain, and the defect was restored by an in trans complementation. The intraperitoneal 50% lethal dose of the R62H/D77N strain increased by 26-and 238,000-fold in normal and iron-overloaded mice, respectively. The growth of the R62H/D77N strain in 50% HeLa cell lysate, 100% human ascitic fluid, and 50% human serum was significantly retarded compared to that of the isogenic wild-type strain. The R62H/D77N mutant also had a critical defect in the ability to survive and replicate even in iron-overloaded mice. These results demonstrate that pyrH is essential for the in vivo survival and growth of V. vulnificus and should be an attractive new target for the development of antibacterial drugs and replication-controllable live attenuated vaccines.Vibrio vulnificus is an estuarine bacterium that opportunistically infects a human being through the consumption of contaminated seafood or wound infection. V. vulnificus septicemia preferentially occurs in patients with underlying hepatic diseases or other immunocompromised conditions and results in a rapid progress and high mortality rate of Ͼ50% (10,22,35). During the infectious process, the V. vulnificus is confronted with dramatic environmental changes, and the bacteria seem to cognitively sense the changes in the host milieu. For the successful infection, V. vulnificus should establish coordinated spatiotemporal expression of various virulence genes in vivo (11, 12). Our group has previously reported 12 in vivo expressed genes by using in vivo-induced antigen technology (17). Among them, pyrH encodes UMP kinase, which catalyzes phosphorylation of UMP to UDP (24, 26). It was reported that UMP kinase senses the environmental pyrimidine pool and directly regulates pyrimidine-specific CarP1 promoter of carbamoylphosphate synthetase of Escherichia coli responsible for the early stage de novo synthesis of pyrimidines (15). Klarsfeld et al. have reported that pyrE of Listeria monocytogenes, another de novo pyrimidine biosynthetic gene, preferentially expressed the intracellular milieu of host cells through a transposon mutant library screening experiment (18). These previous reports suggest that limited availability of pyrimidines i...
Bacterial flagellin, which activates Toll-like receptor 5 and cytosolic pattern recognition receptor Ipaf, has a strong immunomodulatory activity. In the present study, we examined whether intranasal co-administration of flagellin with allergen could modulate established airway hyperresponsiveness and Th2 response using an ovalbumin (OVA)-sensitized mouse model. Balb/c mice sensitized with OVA were treated with OVA-flagellin (FlaB) mixture three times at 1-week intervals. Seven days after the final OVA-FlaB administration, the mice were challenged with OVA inhalation, and airway responses and OVA-specific immune responses were evaluated. The OVA-FlaB treatment significantly suppressed OVA-induced airway hyperresponsiveness, airway eosinophilic inflammation, and OVA-specific Th2 cytokine productions in splenocytes. These results indicate that flagellin co-administered with allergen can modulate airway inflammatory response through inhibition of Th2 responses, and flagellin can be considered as a component for allergen-specific immunotherapy.
Human intestinal maltase (HMA) is an αglucosidase responsible for the hydrolysis of α-1,4-linkages from the non-reducing end of malto-oligosaccharides. HMA has become an important target in the treatment of type-2 diabetes. In this study, epigallocatechin gallate (EGCG) and EGCG glucoside (EGCG-G1) were identified as inhibitors of HMA by an in vitro assay with IC 50 of 20 ± 1.0 and 31.5 ± 1.0 µM, respectively. A Lineweaver-Burk plot confirmed that EGCG and EGCG-G1 were competitive inhibitors of maltose substrate against HMA and inhibition kinetic constants (K i ) calculated from a Dixon plot were 5.93 ± 0.26 and 7.88 ± 0.57 µM, respectively. Both EGCG and EGCG-G1 bound to the active site of HMA with numerous hydrophobic and hydrogen bond interactions.
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