Soil is a complex niche， where survival of microorganisms is at risk due to the presence of antimicrobial agents. Many microbes chemically modify cytotoxic compounds to block their deleterious effects. Streptothricin is a broad-spectrum antibiotic produced by streptomycetes that affects Gram-positive and Gram-negative bacteria alike. Here we identify the SatA (for treptothricin ceyltransferase ， formerly YyaR) enzyme of as the mechanism used by this soil bacterium to detoxify streptothricin. strains lacking were susceptible to streptothricin. Ectopic expression of restored streptothricin resistance to (SatA) strains. Purified SatA acetylated streptothricin at the expense of acetyl-coenzyme A (acetyl-C... More
Soil is a complex niche， where survival of microorganisms is at risk due to the presence of antimicrobial agents. Many microbes chemically modify cytotoxic compounds to block their deleterious effects. Streptothricin is a broad-spectrum antibiotic produced by streptomycetes that affects Gram-positive and Gram-negative bacteria alike. Here we identify the SatA (for treptothricin ceyltransferase ， formerly YyaR) enzyme of as the mechanism used by this soil bacterium to detoxify streptothricin. strains lacking were susceptible to streptothricin. Ectopic expression of restored streptothricin resistance to (SatA) strains. Purified SatA acetylated streptothricin at the expense of acetyl-coenzyme A (acetyl-CoA). A single acetyl moiety transferred onto streptothricin by SatA blocked the toxic effects of the antibiotic. SatA bound streptothricin with high affinity ( [dissociation constant] = 1 μM)， and did not bind acetyl-CoA in the absence of streptothricin. Expression of in conferred streptothricin resistance， indicating that SatA was necessary and sufficient to detoxify streptothricin. Using this heterologous system， we showed that the SatA homologue from also had streptothricin acetyltransferase activity. Our data highlight the physiological relevance of lysine acetylation for the survival of in the soil. Experimental support is provided for the functional assignment of gene products of the soil-dwelling bacilli and This study focuses on one enzyme that is necessary and sufficient to block the cytotoxic effects of a common soil antibiotic. The enzyme alluded to is a member of a family of proteins that are broadly distributed in all domains of life but poorly studied in and The initial characterization of the enzyme provides insights into its mechanism of catalysis.
