Biological patterns: directed by intracellular currents

The formation of patterns is a universal phenomenon that underlies fundamental processes in biology. For example, concentration patterns of proteins position and control important processes in cells, such as cell division, polarity and movement. These protein patterns arise from the interplay of chemical reactions and the spatial transport of proteins.

In principle, transport can occur passively (by diffusion) or actively (by currents). Unlike diffusion, transport by currents has a clear preferred direction. The influence of currents on protein patterns has been little researched to date. A team led by LMU physicist Professor Erwin Frey, in collaboration with Cees Dekker, Professor at Delft University of Technology, has now investigated this aspect using the example of the Min protein system of E. coli.

The researchers combined numerical simulations of theoretical models and experiments with Min proteins in microfluidic chambers in which the proteins bind to synthetic membranes. The scientists were able to show that fluid flows cause movement and alignment of the membrane-bound protein patterns. Surprisingly, the wavy patterns can move both with and against the direction of the flow. Which case occurs depends on the ratio of the protein concentrations. The researchers show how the direction of movement of the patterns subtly depends on the chemical reactions between the proteins.

„The direction of propagation is different because the mass flow shifts the protein concentrations in the cytoplasm, but has no direct effect on proteins that are already bound to the membrane,“ says Frey. „Thus, the response to the flow depends on the accumulation and deposition of proteins at the membrane.“ As the researchers report, fluid flows could therefore be used as a versatile tool to control protein patterns and study molecular mechanisms of pattern formation.

Press release "Ludwig-Maximilians-Universität München" from 30 January 2023