Petraitis, V. | bioRxiv Science

bioRxiv2025

Identification and characterization of a small-molecule inhibitor of the Pseudomonas aeruginosa SOS response

The SOS response is among the most conserved pathways that promote the acquisition of antibiotic resistance in bacteria. This study aimed to identify and characterize small-molecule inhibitors of the SOS response system in the opportunistic pathogen Pseudomonas aeruginosa. A library of 318 drug-like compounds was screened for inhibition of RecA-induced LexA autoproteolysis, a key step in SOS activation. One hit compound, 3-(2-sulfanylanilino)propanoic acid, showed dose-dependent inhibition with an IC50 in the mid-micromolar range. Differential scanning fluorimetry and isothermal titration calorimetry analysis revealed that A12 binds to both RecA and LexA with low micromolar affinity. Mass spectrometry analysis demonstrated that A12 covalently modifies RecA likely via condensation, while it forms a disulfide bond with Cys104 of LexA. Inhibition was diminished under reducing conditions, confirming disulfide formation is crucial for A12 activity. Importantly, A12 did not impair LexAs ability to bind SOS box DNA sequences, which is needed to keep the SOS genes repressed. While A12s potency requires optimization, it represents a promising scaffold for developing anti-SOS compounds targeting P. aeruginosa.

biochemistry↗

bioRxiv2024

Synthesis of Novel N-Substituted β-Amino Acid Derivatives Bearing 2-Hydroxyphenyl Moieties as Promising Antimicrobial Candidates Targeting Multidrug-Resistant Gram-Positive Pathogens

The increasing prevalence of antimicrobial resistance among ESKAPE group pathogens presents a significant challenge in the healthcare sector, contributing to higher morbidity and mortality rates globally. Thus, it is essential to develop novel antimicrobial agents effective against drug-resistant pathogens. In this study, we report the synthesis and in vitro antimicrobial activity characterization of novel N-substituted {beta}-amino acid derivatives bearing 2-hydroxyphenyl core against multidrug-resistant bacterial pathogens. The synthesized compounds (2-26) exhibited promising antimicrobial activity specifically against Gram-positive bacteria, with minimum inhibitory concentrations (MIC) ranging from 4 to 128 {micro}g/mL. None of the compounds demonstrated activity against Gram-negative pathogens or drug-resistant fungi. Compounds 9 (R = 4-nitrophenyl), 17 (R = 5-nitro-2-thienyl), 18 (R = 5-nitro-2-furyl), thiosemicarbazide 16, and 26 exhibited the most promising activity against Staphylococcus aureus MRSA USA300 lineage strain TCH-1516, with MIC values between 4 and 16 {micro}g/mL. Compound 26 demonstrated strong antimicrobial activity against both S. aureus TCH-1516 and E. faecalis AR-0781, with the activity comparable to control antibiotics. These findings indicate that N-substituted {beta}-amino acid derivatives with a 2-hydroxyphenyl core warrant further investigation as a potential scaffold for the further development of antimicrobial agents based on compound 26 targeting Gram-positive pathogens.

microbiology↗