Biology subjects

Karputs, A.

Publications and source records attributed to Karputs, A..

2 recordsLinked to original sources

bioRxiv2026

Diverse Ligands for Mycobacterial CYP124 Identified from Plant and Marine Compounds

Tuberculosis persists as a major global health threat, significantly exacerbated by the rise of drug-resistant strains. Cytochrome P450 of 124 family CYP124 from Mycobacterium tuberculosis (CYP124), implicated in host sterol metabolism and bacterial virulence, represents an emerging and promising therapeutic target. While its precise physiological role was previously debated, CYP124s confirmed ability to metabolize immunomodulatory host sterols underscores its pharmacological relevance. Utilizing surface plasmon resonance binding assays and UV-Vis spectral titration screening, we identified nine novel non-azole ligands for CYP124 from a library of 32 plant-derived and marine natural compounds. Among these hits, (25S)-5-cholestane-3{beta},4{beta},6,7,8,15{beta},16{beta},26-octaol (termed 15{beta}-octaol) and henricioside H2 (HD-4) induced characteristic difference spectra and formed long-lived inhibitory complexes with CYP124, exhibiting dissociation half-lives of 181 min and 65 min, respectively. However, their inhibitory potency was moderate, with IC50 values of approximately 86 M for 15{beta}-octaol and exceeding 100 M for HD-4. Complementary in silico molecular docking and analysis identified key conserved hydrophobic residues within the CYP124 active site crucial for ligand binding, suggesting a shared pharmacophore. Furthermore, structural similarity analysis revealed that 37 human endogenous metabolites, including known immunoregulatory sterols, bear resemblance to the identified CYP124 ligands. This finding points towards a potential sterol-mediated interplay at the host-pathogen interface. Collectively, these results provide a foundation for the future development of mechanism-based CYP124 inhibitors as therapeutics against multidrug-resistant tuberculosis.

biochemistry↗

bioRxiv2025

True-atomic-resolution insights into the interactions of antibiotic rifampicin and rifamycin derivatives with orphan CYP143 of M.tuberculosis.

Analysis of drug-resistant strains of M.tuberculosis revealed a mutation in cytochrome P450 CYP143 gene located in the ESX-5 secretion cluster. The function of CYP143 is unknown. Available synteny information is insufficient to straightforwardly infer potential CYP143 substrates, because a full set of effector proteins/substrates exported by the ESX-5 secretion system has not yet been identified. Here we found that CYP143 is highly conserved among mycobacteria. We leverage the possible association of the G334A mutation in CYP143 with the development of resistance to test the frontline antitubercular drug rifampicin using purified proteins. Binding of rifampicin does not induce typical P450 spectral response, while the crystal structure at atomic resolution reveals the binding mode in the active site. The drug binds above the heme and adopts "closed" conformation of the ansa chain running almost parallel to the naphthoquinone core. In this conformation the oxygen atom bridging C12 and C29 of the macrocycle makes a hydrogen bond with a water molecule coordinating heme iron. The same binding mode was observed in crystal structures in complex with rifaximin, rifamycin S and two synthetic derivatives. In the ligand-bound state the protein retains an open conformation even in the presence of the redox partner, as evident from the crystal structure of the ternary complex. Despite binding close to the heme, no conversion was observed showing that either the rifamycins or the reduction system, or both, are insufficient to support a full catalytic cycle. These results pave the way to understand the development of rifampicin resistance/tolerance and the role of orphan CYPome of M.tuberculosis.

biochemistry↗