Emergence of fractal geometries in the evolution of a metabolic enzyme
分形
统计物理学
生物
物理
数学
数学分析
作者
Franziska Sendker,Yat Kei Lo,Thomas Heimerl,Stefan Bohn,Louise Jeanette Pauline Persson,Christopher-Nils Mais,Wiktoria Sadowska,Nicole Paczia,E. Michael Nussbaum,María del Carmen Sánchez Olmos,Karl Forchhammer,Daniel Schindler,Tobias J. Erb,Justin L. P. Benesch,Erik Marklund,Gert Bange,Jan M. Schuller,Georg K. A. Hochberg
Fractals are patterns that are self-similar across multiple length-scales1. Macroscopic fractals are common in nature2-4; however, so far, molecular assembly into fractals is restricted to synthetic systems5-12. Here we report the discovery of a natural protein, citrate synthase from the cyanobacterium Synechococcus elongatus, which self-assembles into Sierpiński triangles. Using cryo-electron microscopy, we reveal how the fractal assembles from a hexameric building block. Although different stimuli modulate the formation of fractal complexes and these complexes can regulate the enzymatic activity of citrate synthase in vitro, the fractal may not serve a physiological function in vivo. We use ancestral sequence reconstruction to retrace how the citrate synthase fractal evolved from non-fractal precursors, and the results suggest it may have emerged as a harmless evolutionary accident. Our findings expand the space of possible protein complexes and demonstrate that intricate and regulatable assemblies can evolve in a single substitution.