Poster abstracts
Poster number 162 submitted by Clifford Yerby
Simultaneous binding of aminoglycosides to the ribosome could rationalize the increased bactericidal activity
Clifford Yerby (Departmanet of Biological Sciences and University of Illinois at Chicago), Neera Kadiyala (Department of Pharmacy Practice and University of Illinois at Chicago), Zackery Bulman (Department of Pharmacy Practice and University of Illinois at Chicago), Yury S. Polikanov (Departmanet of Biological Sciences and University of Illinois at Chicago)
Abstract:
Due to rapid onset of antimicrobial resistance, the need for more effective treatments of bacterial infections is urgent. Translational control and regulation are vital for normal cellular function. Antibiotics that inhibit protein synthesis by targeting the ribosome can be detrimental to the bacteria. Aminoglycosides (AMGs) are a group of ribosome-targeting antibiotics that bind to the 30S subunit of the ribosome and can effectively kill bacteria, partially by inducing miscoding. Previously it has been shown that combinations of antibiotics can have improved efficacy in killing bacteria compared to single AMG treatment. We have identified AMGs that show improved anti-bacterial effects in combination – streptomycin with paromomycin, gentamicin, or apramycin. All of these are from different sub-classes of AMGs, but still bind at the top of helix 44 of the 16S rRNA in the decoding center of the ribosome. Interestingly, superimposition of the ribosome-bound shows overlapping binding sites for gentamicin, apramycin, and paromomycin; however, streptomycin does not clash with the others and has a distinct site. Furthermore, preliminary data has shown bacterial ribosomes treated with gentamicin and streptomycin in vitro displayed higher miscoding than single AMG treatment, perhaps due to a better binding to the ribosome when both AMGs are present. To date, there are no structures showing how different AMGs can bind to the 70S ribosome simultaneously and possibly rationalize their improved bactericidal activity. To bridge this gap, we have obtained several high-resolution X-ray structures of Thermus thermophilus 70S ribosome in complex with AMGs the bind at the top of helix 44 (gentamicin, apramycin, or paromomycin) and streptomycin. Our structures show that streptomycin is able to bind to the ribosome simultaneously with AMGs from other sub-classes, rationalizing the observed cooperativity of AMG action.
Keywords: Ribosome, X-ray crystallography, Aminoglycosides