RESUMEN
Novel (non-fluoroquinolone) inhibitors of bacterial type II topoisomerases (NBTIs) are an emerging class of antibacterial agents. We report an optimized series of cyclobutylaryl-substituted NBTIs. Compound 14 demonstrated excellent activity both in vitro (S. aureus MIC90=0.125µg/mL) and in vivo (systemic and tissue infections). Enhanced inhibition of Topoisomerase IV correlated with improved activity in S. aureus strains with mutations conferring resistance to NBTIs. Compound 14 also displayed an improved hERG IC50 of 85.9µM and a favorable profile in the anesthetized guinea pig model.
Asunto(s)
Antibacterianos/farmacología , Girasa de ADN/metabolismo , Topoisomerasa de ADN IV/antagonistas & inhibidores , Quinolinas/farmacología , Inhibidores de Topoisomerasa II/farmacología , Inhibidores de Topoisomerasa/farmacología , Animales , Antibacterianos/síntesis química , Antibacterianos/química , Topoisomerasa de ADN IV/metabolismo , Relación Dosis-Respuesta a Droga , Canales de Potasio Éter-A-Go-Go/metabolismo , Cobayas , Humanos , Pruebas de Sensibilidad Microbiana , Estructura Molecular , Quinolinas/síntesis química , Quinolinas/química , Staphylococcus aureus/efectos de los fármacos , Staphylococcus aureus/enzimología , Streptococcus pyogenes/efectos de los fármacos , Streptococcus pyogenes/enzimología , Relación Estructura-Actividad , Inhibidores de Topoisomerasa II/síntesis química , Inhibidores de Topoisomerasa II/química , Inhibidores de Topoisomerasa/síntesis química , Inhibidores de Topoisomerasa/químicaRESUMEN
A structurally novel set of inhibitors of bacterial type II topoisomerases with potent in vitro and in vivo antibacterial activity was developed. Dual-targeting ability, hERG inhibition, and pharmacokinetic properties were also assessed.
Asunto(s)
Antibacterianos/farmacología , Topoisomerasa de ADN IV/antagonistas & inhibidores , Inhibidores Enzimáticos/farmacología , Quinolinas/farmacología , Staphylococcus aureus/efectos de los fármacos , Streptococcus pneumoniae/efectos de los fármacos , Inhibidores de Topoisomerasa II , Animales , Antibacterianos/administración & dosificación , Antibacterianos/química , Girasa de ADN/metabolismo , Topoisomerasa de ADN IV/metabolismo , ADN-Topoisomerasas de Tipo II/metabolismo , Relación Dosis-Respuesta a Droga , Inhibidores Enzimáticos/administración & dosificación , Inhibidores Enzimáticos/química , Canales de Potasio Éter-A-Go-Go/antagonistas & inhibidores , Humanos , Pruebas de Sensibilidad Microbiana , Estructura Molecular , Quinolinas/administración & dosificación , Quinolinas/química , Ratas , Staphylococcus aureus/enzimología , Streptococcus pneumoniae/enzimología , Relación Estructura-ActividadRESUMEN
Recent studies have demonstrated that bacteria possess an essential protein translocation system similar to mammalian signal recognition particle (SRP). Here we have identified the Ffh, a homologue of the mammalian SRP54 subunit from S. pneumoniae. Ffh is a 58-kDa protein with three distinct domains: an N-terminal hydrophilic domain (N-domain), a G-domain containing GTP/GDP binding motifs, and a C-terminal methionine-rich domain (M-domain). The full-length Ffh and a truncated protein containing N and G domains (Ffh-NG) were overexpressed in E. coli and purified to homogeneity. The full-length Ffh has an intrinsic GTPase activity with k(cat) of 0.144 min(-1), and the K(m) for GTP is 10.9 microM. It is able to bind to 4.5S RNA specifically as demonstrated by gel retardation assay. The truncated Ffh-NG has approximately the same intrinsic GTPase activity to the full-length Ffh, but is unable to bind to 4.5S RNA, indicating that the NG domain is sufficient for supporting intrinsic GTP hydrolysis, and that the M domain is required for RNA binding. The interaction of S. pneumoniae Ffh with its receptor, FtsY, resulted in a 20-fold stimulation in GTP hydrolysis. The stimulation was further demonstrated to be independent of the 4.5S RNA. In addition, a similar GTPase stimulation is also observed between Ffh-NG and FtsY, suggesting that the NG domain is sufficient and the M domain is not required for GTPase stimulation between Ffh and FtsY.