Wednesday, 4 February 2015

New antibiotic resistance mechanism

There are two main families of bacteria: those that are surrounded by a single membrane (or one outer wall) and those that are surrounded by two membranes (or two outer walls).

Scientists have examined a protein that is found between these two protective walls, known as RcsF. When all is well, this protein is continually sent to the second outer wall. However, if the bacterium is attacked (by an antibiotic, for instance) the machinery that sends RcsF to the outer wall no longer works: instead of being on the second outer wall, RcsF is stuck between the two fortifications (membranes), from where it sends out an alarm signal. This signal prompts the bacterium to trigger defence systems (by sending other back-up proteins) so as to resist the attacking antibiotic.

In this process, the researchers succeeded in discovering how the protein RcsF manages to sound the alarm. In practical terms, when it is stressed, stuck between the two walls, RcsF contacts another protein, IgaA. The interaction between these two proteins raises the alarm.

For further details see:

Seung-Hyun Cho, Joanna Szewczyk, Christina Pesavento, Matylda Zietek, Manuel Banzhaf, Paula Roszczenko, Abir Asmar, Géraldine Laloux, Ann-Kristin Hov, Pauline Leverrier, Charles Van der Henst, Didier Vertommen, Athanasios Typas, Jean-François Collet. Detecting Envelope Stress by Monitoring β-Barrel Assembly. Cell, 2014; 159 (7): 1652 DOI: 10.1016/j.cell.2014.11.045

Posted by Tim Sandle