ABSTRACT
In this study, we designed and synthesized a series of thiophen-2-iminothiazolidine derivatives from thiophen-2-thioureic with good anti-Trypanosoma cruzi activity. Several of the final compounds displayed remarkable trypanocidal activity. The ability of the new compounds to inhibit the activity of the enzyme cruzain, the major cysteine protease of T. cruzi, was also explored. The compounds 3b, 4b, 8b and 8c were the most active derivatives against amastigote form, with significant IC50 values between 9.7 and 6.03µM. The 8c derivative showed the highest potency against cruzain (IC50=2.4µM). Molecular docking study showed that this compound can interact with subsites S1 and S2 simultaneously, and the negative values for the theoretical energy binding (Eb=-7.39kcal·mol(-1)) indicates interaction (via dipole-dipole) between the hybridized sulfur sp(3) atom at the thiazolidine ring and Gly66. Finally, the results suggest that the thiophen-2-iminothiazolidines synthesized are important lead compounds for the continuing battle against Chagas disease.
Subject(s)
Thiazolidines/pharmacology , Thiophenes/pharmacology , Trypanocidal Agents/pharmacology , Trypanosoma cruzi/drug effects , Animals , Cell Line , Cysteine Endopeptidases , Cysteine Proteinase Inhibitors/chemical synthesis , Cysteine Proteinase Inhibitors/pharmacology , Cysteine Proteinase Inhibitors/toxicity , Glycine/chemistry , Mice , Molecular Docking Simulation , Octoxynol , Protozoan Proteins/antagonists & inhibitors , Thiazolidines/chemical synthesis , Thiazolidines/toxicity , Thiophenes/chemical synthesis , Thiophenes/toxicity , Thiourea/analogs & derivatives , Thiourea/chemical synthesis , Thiourea/pharmacology , Thiourea/toxicity , Trypanocidal Agents/chemical synthesis , Trypanocidal Agents/toxicityABSTRACT
Replication protein A-1 (RPA-1) is a single-stranded DNA-binding protein involved in DNA metabolism. We previously demonstrated the interaction between LaRPA-1 and telomeric DNA. Here, we expressed and purified truncated mutants of LaRPA-1 and used circular dichroism measurements and molecular dynamics simulations to demonstrate that the tertiary structure of LaRPA-1 differs from human and yeast RPA-1. LaRPA-1 interacts with telomeric ssDNA via its N-terminal OB-fold domain, whereas RPA from higher eukaryotes show different binding modes to ssDNA. Our results show that LaRPA-1 is evolutionary distinct from other RPA-1 proteins and can potentially be used for targeting trypanosomatid telomeres.
Subject(s)
DNA, Single-Stranded/metabolism , Leishmania , Protozoan Proteins/chemistry , Protozoan Proteins/metabolism , Replication Protein A/chemistry , Replication Protein A/metabolism , Telomere/genetics , Amino Acid Sequence , Computer Simulation , Humans , Models, Molecular , Molecular Sequence Data , Oligonucleotides/metabolism , Oligosaccharides/metabolism , Protein Binding , Protein Structure, Tertiary , Species SpecificityABSTRACT
Leishmania amazonensis causes a wide spectrum of leishmaniasis. There are no vaccines or adequate treatment for leishmaniasis, therefore there is considerable interest in the identification of new targets for anti-leishmania drugs. The central role of telomere-binding proteins in cell maintenance makes these proteins potential targets for new drugs. In this work, we used a combination of purification chromatographies to screen L. amazonensis proteins for molecules capable of binding double-stranded telomeric DNA. This approach resulted in the purification of a 38kDa polypeptide that was identified by mass spectrometry as Rbp38, a trypanosomatid protein previously shown to stabilize mitochondrial RNA and to associate with nuclear and kinetoplast DNAs. Western blotting and supershift assays confirmed the identity of the protein as LaRbp38. Competition and chromatin immunoprecipitation assays confirmed that LaRbp38 interacted with kinetoplast and nuclear DNAs in vivo and suggested that LaRbp38 may have dual cellular localization and more than one function.
