Forcing bacteria to go bald could help to combat infections.

Researchers at Umeå University, Sweden, and Washington University in St Louis, US, have studied how the hair-like pili on a bacterium's surface can be reduced using chemicals called pilicides. 

Pili are made of proteins and help bacteria bind to cells. Fredrik Almqvist and co-workers had already established that pilicides disrupt pili formation in Escherichia coli. Now, they have found that pilicides do this by limiting the number of pili formed, but without affecting their physical properties. The team showed that when individual pili are grown in solutions containing pilicides they have the same structural and biomechanical properties as normal pili. Their component proteins are correctly folded and anchored to the bacterial cell surface.

The researchers suggested that pilicides suppress the number of pili by affecting molecular chaperones, proteins or protein complexes that help assemble the pili structures.

By reducing the number of these hair-like assemblies, pilicides reduce a bacterium's ability to stick to a surface, such as a cell wall. For some types of bacteria, such as uropathogenic strains of E. coli, this pili-cell binding plays an important role in infection. Almqvist said that pilicides allowed researchers to 'investigate how bald a bacterium could be, and still be infectious' and 'the goal was to eventually create new antibiotics'. 

Pilicides will be 'invaluable tools for dissecting the role of pili in the adhesion of cells to surfaces and the infection of host tissues by bacteria,' said Douglas Weibel, a biochemist at University of Wisconsin-Madison, US. 'This is a terrific example of the application of chemical biology to manipulate organelle biosynthesis in bacteria with a clear relevance to biomedicine,' he added.

Russell Johnson