In silico and in vitro analyzes of N-acyl homoserine lactonase activity in QQ (Quorum Quenching) bacteria

Project no. 24187 · Status: Kapanmış · 2022

Summary

The communication mechanism dependent on cell-cell interaction and population density is called the quorum sensing system and is seen in many bacterial species. Quorum Sensing (QS) regulation enables bacteria to control their gene expression in response to their population density. Bacteria produce signaling molecules at certain stages of their growth process. When these signals reach a certain threshold concentration (usually 1011 cfu/ml), they activate a regulator that can activate or repress target genes. Bacteria synthesize virulence factors (various enzymes, exotoxins, endotoxins, antimicrobial resistance), which are the source of important infectious diseases, through this system. Microorganisms that reach a certain population density have higher resistance to antimicrobials than planktonic bacteria. Many signaling molecules have been identified in bacteria, and signaling molecules called acyl homoserine lactone (AHL) are commonly used in Gram-negative bacteria. After the discovery that the QS system is responsible for the regulation of virulence factors, inhibition of this system is considered as new treatment strategies in the fight against antimicrobial resistance. In this study, seven Bacillus strains with Quorum quenching (QQ) activity were isolated using a Penicillin G-supplemented enrichment medium. The gene encoding AHL-lactonase (aiiA) was amplified by PCR and sequenced. Multiple sequence alignment was applied to the amino acid sequences. Docking studies were performed with C6HSL using AutoDock tools. AiiA amino acid sequence alignment revealed that 74.9% of amino acid sequences are conserved in the Bacillus genus. Binding of C6HSL to the wild type (3DHA) and the H97D variant reduced the docking score for the mutated protein by only 0.1 kcal/mol. This research contributed to the diversification of organisms with QQ activity and beta-lactam antibiotic resistance.

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