Increasing MinD’s Membrane Affinity Yields Standing Wave Oscillations and Functional Gradients on Flat Membranes

The formation of
large-scale patterns through molecular self-organization
is a basic principle of life. Accordingly, the engineering of protein
patterns and gradients is of prime relevance for synthetic biology.
As a paradigm for such pattern formation, the bacterial MinDE protein
system is based on self-organization of the ATPase MinD and ATPase-activating
protein MinE on lipid membranes. Min patterns can be tightly regulated
by tuning physical or biochemical parameters. Among the biochemically
engineerable modules, MinD’s membrane targeting sequence, despite
being a key regulating element, has received little attention. Here
we attempt to engineer patterns by modulating the membrane affinity
of MinD. Unlike the traveling waves or stationary patterns commonly
observed in vitro on flat supported membranes, standing-wave
oscillations emerge upon elongating MinD’s membrane targeting
sequence via rationally guided mutagenesis. These patterns are capable
of forming gradients and thereby spatially target co-reconstituted
downstream proteins, highlighting their functional potential in designing
new life-like systems.