RESUMEN
Infections with the Gram-negative coccobacillus Acinetobacter baumannii are a major threat in hospital settings. The progressing emergence of multidrug-resistant clinical strains significantly reduces the treatment options for clinicians to fight A. baumannii infections. The current lack of robust methods to genetically manipulate drug-resistant A. baumannii isolates impedes research on resistance and virulence mechanisms in clinically relevant strains. In this study, we developed a highly efficient and versatile genome-editing platform enabling the markerless modification of the genome of A. baumannii clinical and laboratory strains, regardless of their resistance profiles. We applied this method for the deletion of AdeR, a transcription factor that regulates the expression of the AdeABC efflux pump in tigecycline-resistant A. baumannii, to evaluate its function as a putative drug target. Loss of adeR reduced the MIC90 of tigecycline from 25 µg/ml in the parental strains to 3.1 µg/ml in the ΔadeR mutants, indicating its importance in the drug resistance phenotype. However, 60% of the clinical isolates remained nonsusceptible to tigecycline after adeR deletion. Evolution of artificial tigecycline resistance in two strains followed by whole-genome sequencing revealed loss-of-function mutations in trm, suggesting its role in an alternative AdeABC-independent tigecycline resistance mechanism. This finding was strengthened by the confirmation of trm disruption in the majority of the tigecycline-resistant clinical isolates. This study highlights the development and application of a powerful genome-editing platform for A. baumannii enabling future research on drug resistance and virulence pathways in clinically relevant strains.
Asunto(s)
Transportadoras de Casetes de Unión a ATP/genética , Infecciones por Acinetobacter/tratamiento farmacológico , Acinetobacter baumannii/genética , Antibacterianos/farmacología , Farmacorresistencia Bacteriana Múltiple/genética , Edición Génica/métodos , Minociclina/análogos & derivados , Transportadoras de Casetes de Unión a ATP/metabolismo , Infecciones por Acinetobacter/microbiología , Acinetobacter baumannii/efectos de los fármacos , Acinetobacter baumannii/aislamiento & purificación , Secuencia de Bases , Técnicas de Sustitución del Gen , Técnicas de Inactivación de Genes , Genoma Bacteriano/genética , Pruebas de Sensibilidad Microbiana , Minociclina/farmacología , Análisis de Secuencia de ADN , TigeciclinaRESUMEN
Protein kinases are among the most attractive therapeutic targets for a broad range of diseases. This feature review highlights and classifies the main design principles employed to generate active and selective kinase inhibitors. In particular, emphasis is focused on a fragment-based lead-generation approach, which constitutes a novel design method for developing type II kinase inhibitors with distinct binding kinetic attributes. This 'retro-design' strategy relies on a customized fragment library, and contrasts the traditional approach used in the design of type II inhibitors.