The study is being published in ScienceXpress, an advance online edition of the journal Science, on May 5.
"The development of antibiotics to treat infectious disease is being seriously undermined by the emergence of drug-resistant bacteria," says Geoffrey A. Chang, Ph.D., a Scripps Research associate professor and a member of the Skaggs Institute for Chemical Biology, who led the study. "Multidrug resistance develops in part through the expulsion of drugs by integral membrane transporters like EmrD. Determining the structure of this transporter will add significantly to our general understanding of the mechanism of drug transport through the cell membrane and provide the structural basis for how these proteins go about selecting specific drugs to expel."
Multidrug resistant bacterial infections raise the cost of medical treatment and are far more expensive than treating normal infections. Treating drug-resistant tuberculosis, for example, requires so-called second-line drugs if standard treatment fails. According to the Centers for Disease Control, second-line drugs can cost as much as "$33,000 per patient in industrialized countries compared to $84 for first-line drugs." In addition, the centers noted, second-line drugs need to be taken for longer periods of time-from 18 to 36 months-and may require substantial patient monitoring, making these treatments difficult if not impossible to "be available in many of the resource-poor nations where drug-resistant tuberculosis is emerging."
EmrD belongs to the Major Facilitator Superfamily, a group of transporters among the most prevalent in microbial genomes. These transporters are distinctive in their ability to recognize and expel a highly diverse range of amphipathic compounds. Amphipathic molecules contain both hydrophobic and
Contact: Keith McKeown
Scripps Research Institute