Anti-hIV-1 Activity And Mechanism Of Polyether Antibiotics K-41A And K-41Am

ObjectivePolyether antibiotic K-41 A and its analogue K-41 Am were isolated from a marine-derived Streptomyces sp.SCSIO 01680.Polyether K-41 A is a known compound that has the antibacterial activity against gram-positive bacteria and coccidium.In this study,we aim to characterize the anti-HIV activity of K-41 A and K-41 Am as well as the mechanisms involved,in order to provide new clues for anti-HIV-1 drug development.Methods1.Anti-HIV-1 activity assay: Three anti-HIV cell detection systems were established to evaluate the anti-HIV-1 activity,including HIV-1IIIB/TZM-bl system,HIV-1IIIB/MT-2 system,and HIV-1 Ba L/PBMCs system.The anti-HIV-1 activity of K-41 A and K-41 Am was assessed by detecting the expression level of luciferase reporter gene or the level of P24 in TZM-b1 cells.In addition,the impact of drugs on HIV-1 induced cytopathic effect was observed.2.The key enzymes of viruses: Commercial kits were used to determine whether K-41 A and K-41 Am have the inhibitory effects on three key enzymes of HIV-1(reverse transcriptase,integrase and protease).The interaction between drugs and target viral proteins was further analyzed through the online molecular docking site Systemsdock.3.RNA modification: The UPLC-ESI-MS system was used to analyze the dynamic of RNA modification and to assess whether the drugs affects viral replication by regulating RNA modification in the HIV-1 infected group.Results1.Anti-HIV-1 activity assay: We found that polyether antibiotic K-41 A and its analog K-41 Am,which were isolated from a marine-derived Streptomyces sp.SCSIO 01680,possess anti-HIV-1 activity.The inhibitory effects of K-41 A and K-41 Am on HIV-1 replication were observed in HIV-1IIIB/TZM-bl system,HIV-1IIIB/MT-2 system,and HIV-1 Ba L/PBMCs systems,respectively.The 50% inhibitory concentrations(IC50)of K-41 A on HIV-1 replication in the above three systems were 0.7109μM,0.0832μM,and 0.1472μM respectively.The IC50 of K-41 Am were 0.5674μM,0.2336μM,and 1.1535μM respectively.Meanwhile,the protective effect of K-41 A and K-41 Am on cytopathic effect(CPE)induced by HIV-1 was also observed in the three systems.2.Key enzymes of viruses: K-41 A and K-41 Am inhibited the activities of HIV-1 reverse transcriptase(RT)and integrase(IN)in a dose-dependent manner.Both compounds had no inhibitory activity against HIV-1 protease.The IC50 of K-41 A and K-41 Am on RT activity were 1.234 μM and 5.586 μM,respectively.The IC50 of K-41 A and K-41 Am on IN activity were 10.929 μM and 0.354 μM,respectively.In addition,molecular docking shows that there was an interaction between the compound and RT or IN.The docking score of the compound with the target proteins(HIV-1 RT,HIV-1 IN)was equal.The docking score,the amino acid residue,and the number of hydrogen bonds of K-41 A and K-41 Am all exceeded the docking score between the target protein and the natural ligand.3.RNA modification: In the positive control group,the level of m6 A was elevated,the levels of m1 G and m2 G were decreased.Both compounds,particularly K-41 Am,could regulate HIV-1-mediated RNA modification in cells,and reverse m1 G and m2 G modifications caused by HIV-1 infection to normal levels.ConclusionsWe found that K-41 A and K-41 Am possess strong anti-HIV-1 activity.Both compounds exhibited inhibitory effects on HIV-1 reverse transcriptase and integrase,indicating that the two compounds may be the dual-target inhibitor against HIV-1.Furthermore,the compounds could regulate RNA modification of cells or HIV-1 infection.