ABSTRACT
In pathogens, the thioredoxin system forms part of the defense against oxidative stress and ensures the formation of the proper disulfide bonds to ensure protein function. In Corynebacterium pseudotuberculosis, the role and mechanism of TrxA1 has not been elucidated, but, the significant homology among different Trxs and the conservation of the residues that form their active sites underline the importance of the Trx systems. Proteins involved in redox metabolism and low molecular weight thiols, which might interact with them, become attractive targets to modulate the activity of pathogens. The activity of the protein was investigated using a turbidimetric assay system. The influence of different pH and low molecular weight thiols were tested. Additionally, this assay was used to investigate the inhibitory potential of ligands from different molecular families, such as, polyanions (suramin and heparin) and flavonoids (hesperetin and hesperidin). All four compounds showed inhibition of the protein activity by approximately 80%. The interactions between these compounds and Cp-TrxA1 were investigated using CD spectroscopy, NMR, molecular docking and dynamics. Our results demonstrate that suramin and hesperetin can serve as lead molecules for the development of specific inhibitors for the C. pseudotuberculosis TrxA1.
Subject(s)
Corynebacterium pseudotuberculosis/metabolism , Flavonoids/chemistry , Flavonoids/pharmacology , Polymers/chemistry , Polymers/pharmacology , Thioredoxins/antagonists & inhibitors , Thioredoxins/chemistry , Catalytic Domain , Corynebacterium pseudotuberculosis/genetics , Ligands , Magnetic Resonance Spectroscopy , Molecular Conformation , Molecular Docking Simulation , Molecular Dynamics Simulation , Oxidation-Reduction , Polyelectrolytes , Protein Binding , Recombinant Proteins , Structure-Activity Relationship , Thioredoxins/genetics , Thioredoxins/isolation & purificationABSTRACT
Studies examining various spacer groups that link the two aromatic rings of combretastatin A-4 (CA4) have shown that the biological activity of analogs does not require the cis-stilbene configuration of CA4. Oxygen or nitrogen, carbonyl, methylene and ethylene spacers, for example, are present in CA4 analogs that show good activity. Up to now sulfur was not tested for this purpose. In this article we describe the synthesis of sulfide, sulfoxide and sulfone spacers between two aromatic rings comparable to those of CA4. We also compared them with CA4 for inhibitory effects on cell growth, tubulin polymerization, and the binding of [(3)H]colchicine to tubulin. We found that the sulfide is highly active and may be a lead compound for the preparation of antitumor compounds.