Biomics

The widespread use of antibiotics in human and veterinary medicine leads to the emergence of many bacteria resistant to various toxicants. One of the molecular mechanisms of bacterial resistance is the functioning of RND-type efflux systems, which remove antibiotics and heavy metal cations from cells. The aim of this study was to use bioinformatics to characterize the gene cluster of the bacterium Achromobacter insolitus LCu2, which contains three efflux system operons: AxyXY-OprZ, MexVW-TolC, and MexJK-OprM. The annotation of each gene was verified, with the genes of each operon functionally divided into components of the cytoplasmic membrane, outer membrane, and periplasmic adapters. Signal sequences ranging from 15 to 50 amino acid residues were identified at the N-termini of the periplasmic and outer membrane proteins. The amino acid sequences of similar proteins from different operons had a low level of identity (24-31%). However, 3D modeling demonstrated the ability of all proteins to form supramolecular complexes necessary for the functioning of efflux systems. It is hypothesized that the location of the genes for three efflux systems in a single gene cluster facilitates the simultaneous activation of cellular defense mechanisms against a wide range of toxins.

RND-system efflux, 3D modeling, AlphaFold 3, multidrug resistance, Achromobacter insolitus LCu2

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