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Emergence of fractal geometries in the evolution of a metabolic enzyme.

Franziska L SendkerYat Kei LoThomas HeimerlStefan BohnLouise J PerssonChristopher-Nils MaisWiktoria SadowskaNicole PacziaEva NußbaumMaría Del Carmen Sánchez OlmosKarl ForchhammerDaniel SchindlerTobias J ErbJustin L P BeneschErik G MarklundGert BangeJan Michael SchullerGeorg K A Hochberg
Published in: Nature (2024)
Fractals are patterns that are self-similar across multiple length-scales 1 . Macroscopic fractals are common in nature 2-4 ; however, so far, molecular assembly into fractals is restricted to synthetic systems 5-12 . 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.
Keyphrases
  • electron microscopy
  • amino acid
  • genome wide
  • binding protein
  • hydrogen peroxide
  • dna methylation
  • nitric oxide
  • mass spectrometry
  • single molecule