Inhibiting the oligomerization of mycobacterial DNA-directed RNA polymerase(RNAP)using natural compound via in-silico techniques

Mycobacterium tuberculosis(Mtb)is responsible for the spread of tuberculosis(TB).The current study employed virtual screening of 2569 natural compounds against the DNA-directed RNA polymerase(RNAP)of Mtb to identify the possible binders that can inhibit its function.The in-silico methodology included molecular docking to the compounds,further,the stability and flexibility of the best complexes were studied using molecular dynamics simulation,the MM/GBSA binding free energy technique with energy decomposition,PCA,FEL,steered MD simulation,and umbrella sampling.Individual virtual screenings were conducted for the five RNAP subunits(chains A,B,C,D,and E)to identify a compound capable of inhibiting RNAP oligomerization.A promising compound,isoestradiol 3-benzoate,exhibited a low binding score(−7.28kcal/mol to−8.21kcal/mol)and showed binding ability with all subunits of the protein.Thus,the five complexes with isoestradiol 3-benzoate were selected for molecular dynamics simulation analysis.Furthermore,RMSD showed that isoestradiol 3-benzoate bound with chain E showed the lowest RMSD of 0.49nm,while with chains A and B it had the most stable and consistent conformations with RMSD of 1.75nm and 1.2nm,respectively.The H-bond between isoestradiol 3-benzoate and chains C and E showed the highest occupancy(58.27%,45.33%,and 50.80%,42.25%,11.75%).Moreover,the MMPBSA technique showed that isoestradiol 3-benzoate had a strong association with chains B and C(ΔGbind=−126.25±2.03 and−129.27±2.25).Additionally,free energy decomposition,PCA,FEL-steered MD simulation,and umbrella sampling were also performed to validate the association of the ligand with the protein.Isoestradiol 3-benzoate binds strongly to chains B and E;therefore,it should be considered as viable candidate for inhibiting the formation of RNAP protein complex,concluded in this study.

A repetitive DNA-directed program of chromosome packaging during mitosis

Chromosomes, the longest molecular fiber that stores genetic information in eukaryotic cells, must be orderly packaged during mitosis for their proper segregation into daughter cells. Although the morphological changes of chromosomes during mitosis have been described in detail, how mitosis progression programs the transformation of seemingly amorphous and loose interphase .

An extended two-year trial of lamivudine in Chinese patients with chronic hepatitis B

OBJECTIVE: To evaluate the long-term efficacy and safety of lamivudine therapy for the treatment of chronic hepatitis B and the clinical influence of emergence of tyrosine methionine aspartic acid (YMDD) motif mutation of hepatitis B virus (HBV). METHODS: This multicenter, double-blind, randomized, placebo controlled trial began in 1996. A total of 429 patients with HBsAg, HBeAg and HBV CNA positives were enrolled. They were randomized to receive either lamivudine 100 mg daily (n = 322) or placebo (n = 107) on 3 : 1 ratio for the first 12 weeks. Thereafter all patients were offered open label lamivudine treatment and assessed every 4 weeks for a total of 104 weeks. RESULTS: After 1 year treatment 72.7% patients (285/392) had a sustained serum HBV DNA response. HBV DNA continued to be substantially suppressed at the second year, except in patients with the emergence of YMDD mutation whose mean HBV DNA levels increased to 86 Meq/ml (bDNA assay) but were much more lower than that of pre-treatment baseline level. lamivudine therapy resulted in increased HBeAg loss and HBeAg/anti-HBe seroconversion, which were correlated with both baseline alanine transaminase (ALT) levels and also with duration of lamivudine treatment. HBeAg loss was achieved in 26.8% of patients with ALT > 1-fold upper limit of normal at 2 yeas and in 35.6% and 55.6% of patients with ALT > 2-fold upper limit of normal and ALT > 5-fold upper limit of normal, respectively. For HBeAg seroconversion, these figures were 17.4%, 22.2%, and 33.3% respectively. By the end of 2 years, ALT levels were remained in normal ranges in 50.3% whose ALT were abnormal before treatment, and in 83% whose ALT were mormal before treatment. YMDD mutation were developed in 49.7% of the patients. Their serum HBV DNA levels were slightly increased to bDNA median level 86 Meq/ml and 15% of the patients they were ALT exceeded baseline levels. Four patients clinically flared-up and recovered after stop treatment. The adverse drug reactions (ADRs) of lamivudine were mild to moderate, only two patients were reported as drug related severe ADR. CONCLUSION: Sustained HBV replication and clinical improvement could be obtained by the long-term lamivudine therapy with good tolerance and safety.