antibiotic stress, genetic response and altered permeability of e. coli抗生素压力,大肠杆菌的遗传反应和改变磁导率.pdfVIP

Antibiotic Stress, Genetic Response and Altered Permeability of E. coli 1 2 1 1,3 2 1 ` 2 Miguel Viveiros , Myrielle Dupont , Liliana Rodrigues , Isabel Couto , Anne Davin-Regli , Marta Martins , Jean-Marie Pages , Leonard Amaral1* ´ 1 Unit of Mycobacteriology, Unidade de Parasitologia e Microbiologia Medicas (UPMM), Instituto de Higiene e Medicina Tropical, Universidade Nova ´ ´ ´ ´ ´ de Lisboa, Lisboa, Portugal, 2 UMR-MD-1, IFR48, Facultes de Medecine et de Pharmacie, Universite de la Mediterranee, Marseille, France, 3 Centro de ´ ˆ Recursos Microbiologicos (CREM), Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, Lisboa, Portugal Background. Membrane permeability is the first step involved in resistance of bacteria to an antibiotic. The number and activity of efflux pumps and outer membrane proteins that constitute porins play major roles in the definition of intrinsic resistance in Gram-negative bacteria that is altered under antibiotic exposure. Methodology/Principal Findings. Here we describe the genetic regulation of porins and efflux pumps of Escherichia coli during prolonged exposure to increasing concentrations of tetracycline and demonstrate, with the aid of quantitative real-time reverse transcriptase-polymerase chain reaction methodology and western blot detection, the sequence order of genetic expression of regulatory genes, their relationship to each other, and the ensuing increased activity of genes that code for transporter proteins of effl