Riboswitch Regulation of Aminoglycoside Resistance Acetyl and Adenyl Transferases

In our recent paper, we reported an aminoglycoside-sensing RNA in the leader RNA of the aminoglycoside acetyl transferase (AAC) and aminoglycoside adenyl transferase (AAD), enzymes that confer resistance to aminoglycoside antibiotics through modification of the drugs. Our study explains a well-known phenomenon: the induction of expression levels of the AAC/AAD proteins on addition of aminoglycosides (Williams and Northrop, 1976). In this paper, we presented data that showed: (1) aminoglycoside-specific induction of reporter genes mediated by the leader RNA of the AAC in Pseudomonas fluorescens; (2) aminoglycoside binding to the leader RNA by surface plasmon resonance spectroscopy (SPR); (3) that binding induces a structural transition in the leader RNA that can be detected by changes in gel electrophoretic mobility and chemical probing; (4) the identification of a specific aminoglycoside-RNA crosslink; (5) confirmation, via mutational analysis, of the main features of the RNA secondary structure and the importance of structural elements within it for drug binding.