Left Beta-Helix peptides for the design of Artificial Metallo-enzymes – LeBHel-AMzymes

We began by developing a tool to enable us to design sequences of peptides and proteins that fold into Type I ß-helices. This analysis was done on the 78 crystallographic structures of natural ß-helices available to date. The result is the identification of particular motifs that particularly stabilise this folding, which has not been described in the literature to date. Based on this new tool, we designed and synthesised short peptides (thus easier to produce than large proteins) with the aim of self-assembling and folding into Type I ß-helices. The resulting fibres were characterised by various spectroscopies and electron microscopies. Based on this initial proof of concept, we generated metal-binding mutants of this peptide with the aim of conferring catalytic properties to these peptide fibres.

This work has led to two major results. The first is the significant advance in our understanding of the sequence-structure relationship of the Type I ß-helix. In other words, it is a kind of guide to designing peptide and protein sequences that adopt a stable Type I ß-helix fold. The second result is the experimental proof of the relevance of this tool: a peptide that folds (into a ß-helix) by forming fibres of remarkable stability. These first steps pave the way towards new catalysts for continuous flow synthesis.

This project has enabled us to make considerable progress in this new area of research, and to identify a promising avenue: that of short peptides that self-assemble into stable ß-helices. Indeed, in the very near future we will develop metallo-peptides that are catalytic for different types of reactions.
Secondly, having a short motif that allows the formation of stable protein assemblies opens up prospects for the development of bio-sourced catalysts, in particular for enzyme flow catalysis (e.g. «all-enzyme hydrogels«).
Also, the advances obtained in this project will be able to meet a real industrial need, since one of the limitations to the use of enzymes in this environment is the stability of the enzymes and their reuse.

To date, these results have not yet been published. However, two manuscripts are currently being written, and two others are to follow.

In order to reduce the energy consumption of chemical industry, as well as its impact on environment, new catalysts — based on earth abundant elements — are necessary. Catalysts made by anchoring a metal center in a protein scaffold are called artificial metallo-enzymes. The combination of catalytic properties of the metal together with the biological host yields interesting catalytic efficiency, especially in terms of regio- and enantio-selectivity, given that the host can be optimized by directed evolution.
Our project aims at developping a flexible and generalizable approach as a tool for the design of artificial metallo-enzymes. It is based on the engineering of self-assembling peptides, folding into a ß-helix. This JCJC-ANR proposal constitutes the first step towards the ready-to-use tool: the design and characterisation of elementary peptidic bricks, and the control of their assembly.