Molecular simulations confirm role of functional rotation in multidrug resistance

November 22, 2010
Triggering of AcrB drug export and functional rotation by proton-binding. Copyright : RIKEN

A new molecular simulation technique developed by Japanese researchers at RIKEN and Kyoto University has confirmed for the first time the function of the transporter protein AcrB in E. coli multidrug resistance. The result marks a key step in efforts to combat antibiotic resistance, demonstrating the power of computer simulation as an essential tool for basic research.

The capacity of certain bacteria to resist a wide variety of drugs and chemicals, known as “multidrug resistance”, has attracted widespread attention for the threat it poses to global health. One of the key factors that cause such resistance is the overexpression of efflux pumps, protein transporters in the cytoplasmic membrane that flush toxic substances out of the cell.

To clarify the role of efflux pumps in multidrug resistance, the researchers modeled the dynamics of AcrB, a transporter in E. coli which enables the to expel a wide range of target substances, including many antibiotics. Earlier research characterized AcrB as a prism-shaped homo-trimer of three subunits with conformations corresponding to three states in a transport cycle governing access to, binding and extrusion of target substances from the cell. Evidence for this so-called “functional rotation” hypothesis, however, was lacking.

Using a new coarse-grain technique, the research group has now produced this crucial evidence for the first time, and has pinpointed its driving force in proton-binding to AcrB’s drug-bound molecule. The findings also reconcile previous results, which in 2002 described AcrB as a symmetric structure and then in 2006 an asymmetric one, by suggesting that each study describes a different state of the transporter, whose conformation changes during drug dissociation.

Reported in the journal Nature Communications, this verification of the functional rotation mechanism marks a key step forward toward tackling key problems of multidrug resistance. It also hints at breakthroughs to come with the launch of RIKEN’s new Next-Generation Supercomputer (“K Computer”), set to be unveiled in 2012.

Explore further: Antibiotics as active mutagens in the emergence of multidrug resistance

More information: Xin-Qiu Yao, et al. Drug export and allosteric coupling in a multidrug transporter revealed by molecular simulations. Nature Communications 1: 117 (2010)(8 pages). doi: 10.1038/ncomms1116 (2010).

Related Stories

Recommended for you

Scientists develop first catalysed reaction using iron salts

January 20, 2017

Scientists at the University of Huddersfield have developed a new chemical reaction that is catalysed using simple iron salts – an inexpensive, abundant and sustainable alternative to costlier and scarcer metals. The research ...

Chemists cook up new nanomaterial and imaging method

January 20, 2017

A team of chemists led by Northwestern University's William Dichtel has cooked up something big: The scientists created an entirely new type of nanomaterial and watched it form in real time—a chemistry first.

Gecko inspired adhesive can attach and detach using UV light

January 19, 2017

(Phys.org)—A small team of researchers at Kiel University in Germany has developed new technology that emulates the way a gecko uses its toes to cling to flat surfaces. In their paper published in the journal Science Robotics, ...

Treated carbon pulls radioactive elements from water

January 19, 2017

Researchers at Rice University and Kazan Federal University in Russia have found a way to extract radioactivity from water and said their discovery could help purify the hundreds of millions of gallons of contaminated water ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.