Near-Neighbor Relationships of the Atypical Subunits that Form the Peripheral Stalk of the Mitochondrial ATP Synthase in Chlorophycean Algae

Abstract

Biological functions rely on ordered structures and intricately controlled collective dynamics. Such order in living systems is typically established and sustained by continuous dissipation of energy. The emergence of ordered patterns of motion is unique to non-equilibrium systems and is a manifestation of dynamic steady states. Many cellular processes require transitions between different steady states. Can general principles of statistical physics guide our understanding of such cellular self-organization? I will show that model actomyosin cortices, in the presence of rapid turnover, self-organize into three nonequilibrium steady states as a function of network connectivity. The different states arise from a subtle interaction between mechanical percolation of the actin network and myosin-generated stresses. All states show distinct dynamic order. Only the highest connectivity causes structural phase separation. We discover that the dominant mechanism defining the symmetries of the dynamic steady states is the emergence of ordered stress patterns. The marginally percolated state displays strong strain fluctuations, indicative of enhanced susceptibility. The striking dynamics in this model actomyosin cortex were revealed using fluorescent single-walled carbon nanotubes as novel probes. We propose self-organization of stress patterns as a new paradigm of biological function.