Actinobacteria of the Genus Streptomyces–A Reservoir of Aminoglycoside Acetyltransferase Genes

Abstract The lack of success in combating the spread of multidrug resistance in pathogenic bacteria forces the scientific community to analyze at a new level of knowledge of the mechanisms, routes of spread, and natural reservoirs containing bacteria that carry antibiotic resistance genes. The classical mechanism of resistance to aminoglycoside antibiotics (AG) is the modification of AG by enzymes, the most common and clinically significant of which are aminoglycoside acetyltransferases (AAC). In this study, genes encoding enzymes belonging to the AAC(2'), AAC(3), AAC(6'), and Eis subfamilies were identified in the sequenced genomes of Streptomyces strains producing AG. Comparative analysis of amino acid sequences showed that the closest homologs for the identified AAC are acetyltransferases from other species of actinobacteria of the genus Streptomyces that do not produce AG (producers of other classes of antibiotics or not producing antibiotics). Comparative phylogenetic analysis of amino acid sequences showed that the enzymes AAC(2′) and Eis are homologs of the acetyltransferases AAC(2′)-I and Eis, previously identified in mycobacteria. The possible role of Eis acetyltransferases in the acetylation of various substrates upon entry into the human body through vesicles containing them is discussed.