EMBL: Bacteria’s Barrel-building Challenge
Scientists at EMBL Heidelberg have found that bacteria such as E. coli use a plug-like molecule to ensure their insides grow in synch with the envelope that surrounds them.
You have a barrel-making machine, which you must use to churn out barrels and put plugs in them. If you're too slow, or your machine breaks, or you run out of barrel-making materials, plugs will start to accumulate, and an alarm will go off. This video game-like scenario actually plays out inside some bacteria. It is one of the ways in which bacteria like E.coli ensure that they grow safely.
Bacteria like E.coli are like walled cities, with a multi-layered line of defense called the cell envelope. This protective barrier consists of two membranes, between which the cell wall is sandwiched. The ‘barrels' are proteins that stud the outer membrane and serve as channels to allow molecules into and out of the cell. As the bacterial envelope grows, new barrels have to be added. In total, the 4000 or so barrel-making machines in an E.coli bacterium have to be able to produce up to one million barrels. And they have to do so at the right pace: if the envelope stopped growing (or slowed) but the inside of the bacterium continued to expand, the result would be disastrous. Scientists in Nassos Typas' lab at EMBL Heidelberg and collaborators at Université Catholique de Louvain in Belgium have discovered that the efficiency of barrel-making is monitored by the ‘plug' molecule RcsF. RcsF acts as a sensor to detect problems in the assembly process and trigger a chain reaction inside the bacterium to contain the damage and adjust the cell's growth rate.
Read more on what they have found here.
Or within the original publication:
Cho, Szewczyk, Pesavento et al.: Detecting Envelope Stress by Monitoring β-Barrel Assembly. Cell, 18 December 2014. DOI:10.1016/j.cell.2014.11.045