1 / 7

Quorum sensing and multidrug transporters in Escherichia coli

Quorum sensing and multidrug transporters in Escherichia coli. PNAS, 2006, 103 (7): 2386–2391 Shirley Yang, Christopher R. Lopez, and E. Lynn Zechiedrich. quorum sensing  multidrug transporters. Bacteria communicate using small chemical molecules (quorumsensing signals; QSS).

darva
Download Presentation

Quorum sensing and multidrug transporters in Escherichia coli

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Quorum sensing and multidrug transportersin Escherichia coli PNAS, 2006, 103(7): 2386–2391 Shirley Yang, Christopher R. Lopez, and E. Lynn Zechiedrich

  2. quorum sensing  multidrug transporters • Bacteria communicate using small chemical molecules (quorumsensing signals; QSS). • Once a threshold concentration in the growth medium is reached, the QSS activate transcription factors that, in turn, up-regulate the signal synthase and multiple other genes. • Distinct classes of QSS have been discovered in Gram-negative bacteria: the N-acyl homoserine lactones (AHL), the LuxS-derived family, and 2-heptyl-3-hydroxy-4-quinolone (PQS)

  3. Known QSS vary widely in their ability to diffuse across bacterial membranes. • The multidrug resistance (MDR) efflux pump assist the diffusion of the larger AHL signal (3OC12-HSL) from P. aeruginosa. • Overproduction of MDR efflux pump in P. aeruginosa decreased production of virulence factors positively regulated by quorum sensing and decreased extracellular concentrations of 3OC12-HSL. • Microarray analyses in P. aeruginosa show that the expression of at least seven MDR pumps is regulated positively by C4-HSL and 3OC12-HSL.

  4. In E. coli, SdiA, which is homologous to the LuxR family of quorum-sensing transcription factors, is regulated in a density dependent manner. • There are at least three multidrug transporters (AcrAB/TolC, MdfA, and NorE) that exude fluoroquinolones. • SdiA overproduction up-regulation of AcrAB  increased resistance to quinolones and other antibiotics • Lack of SdiA slightly lower AcrB levels  decreased drug resistance

  5. Results: • ΔacrAB, tolC210, or ΔnorE mutants have the same growth rate as WT cells in log phase but grow to higher cell density in stationary phase • Except for mdfA, overproduction of either pump caused cells to reach lower density. • Conditioned medium (CM) from cells overexpressing acrAB represses cell growth more than CM from WT cells. • CM from pump mutant cells represses cell growth less than CM from WT cells. • These results were not affected by the deletion of luxS, which synthesizes the quorum-sensing signal autoinducer 2 (AI-2).

  6. Expression of the rpoS gene encoding the stationary phase σfactor is induced earlier in cells overexpressing acrAB and later in acrAB mutant cells.

More Related