Dresden 2026 – scientific programme

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BP: Fachverband Biologische Physik

BP 21: Focus Session: Sequence Spaces, Populations and Evolution

BP 21.3: Talk

Wednesday, March 11, 2026, 15:45–16:00, HÜL/S386

Bias toward simplicity and symmetry in protein self-assembly — •Prarthana Agrawal — University of Oxford

Symmetry is ubiquitous in protein complexes and other biological assemblies and is often attributed to natural selection. Algorithmic information theory offers an alternative explanation: when structures are generated by simple local rules, outcomes that require less information to specify are intrinsically more likely [1]. Because symmetry enables reuse of the same assembly instructions, symmetric structures typically have low algorithmic (Kolmogorov) complexity and are therefore strongly favored.

We test this idea using a three-dimensional polycube self-assembly model as an abstract representation of protein quaternary structure. By sampling interaction rule spaces, we find a strong bias toward low-complexity assemblies, with symmetric structures occurring far more frequently than asymmetric ones. We further show that not all symmetries are equally accessible: some symmetry operations reduce assembly complexity more effectively than others and are therefore disproportionately likely.

These results indicate that biases toward simple and symmetric structures in self-assembly arise from intrinsic generative constraints rather than natural selection alone, suggesting that evolutionary outcomes are shaped not only by selection but also by how phenotypic variation is generated.

[1] Johnston et al., Proc. Natl. Acad. Sci. U.S.A. 119, e2113883119 (2022)

Keywords: protein self-assembly; algorithmic information theory; tile assembly model; symmetry in protein complexes; Kolmogorov complexity