TY - JOUR T1 - Experimental characterisation of <em>de novo</em> proteins and their unevolved random-sequence counterparts JF - bioRxiv DO - 10.1101/2022.01.14.476368 SP - 2022.01.14.476368 AU - Brennen Heames AU - Filip Buchel AU - Margaux Aubel AU - Vyacheslav Tretyachenko AU - Andreas Lange AU - Erich Bornberg-Bauer AU - Klara Hlouchova Y1 - 2022/01/01 UR - http://biorxiv.org/content/early/2022/01/17/2022.01.14.476368.abstract N2 - De novo gene emergence provides a route for new proteins to be formed from previously non-coding DNA. Proteins born in this way are considered random sequences, and typically assumed to lack defined structure. While it remains unclear how likely a de novo protein is to assume a soluble and stable tertiary structure, intersecting evidence from random-sequence and de novo-designed proteins suggests that native-like biophysical properties are abundant in sequence space. Taking putative de novo proteins identified in human and fly, we experimentally characterise a library of these sequences to assess their solubility and structure propensity. We compare this library to a set of synthetic random proteins with no evolutionary history. Bioin-formatic prediction suggests that de novo proteins may have remarkably similar distributions of biophysical properties to unevolved random sequences of a given length and amino acid composition. However, upon expression in vitro, de novo proteins exhibit higher solubility which is further induced by the DnaK chaperone system. We suggest that while synthetic ran-dom sequences are a useful proxy for de novo proteins in terms of structure propensity, de novo proteins may be better integrated in the cellular system given their higher solubility.Competing Interest StatementThe authors have declared no competing interest. ER -