Engineered proteins as molecular templates for functional materials

Abstract

The current state-of-the-art of biotechnology has improved tremendously over the last decades. Currently, the physico-chemical properties can be manipulated at molecular scale. Bottom-up design of complex functional nanostructures is of the great interest because it allows the synthesis of ordered structures using the intrinsic self-assembly properties of simple components. In this sense, repeat proteins are useful tools for this task due to their modular and hierarchical structure, which can be the basis to construct complex supramolecular assemblies. In this thesis, repeat proteins and in particular consensus tetratricopeptide repeat proteins (CTPR) have been employed to generate higher order structures and to design and fabricate functional materials. CTPR proteins belong to the large family of repeat proteins and consist of a 34 amino acids helix-turn-helix domain. CTPR repeats can be combined in tandem to form superhelical arrays, in which eight repeats comprise one full turn of the superhelix.On the one hand, in this thesis we describe an experimental approach to form higher order architectures by a bottom-up assembly of CTPR building blocks. Introducing a novel interface along the CTPR superhelix allows two CTPR molecules to assemble into protein nanotubes. We designed two models to form protein nanotubes based on electrostatic interactions and on ¿-¿ interactions. These studies provide insights into the design of novel protein interfaces for the control of the assembly into more complex structures, which will open the door to the rational design of nanostructures and ordered materials for many potential applications in nanotechnology. On the other hand, we generate functional films based on repeated proteins with applicability in different fields such as optics and energy production. In particular, we show the formation of nanopatterned protein films labeled with fluorescent dyes to produce Amplified Spontaneous Emission (ASE) and Distributed Feedback (DFB) lasing relevant for sensing. In parallel, protein films are used to entrap active enzymes, without apparent loss of activity. This film is used to generate energy through the catalase enzymatic activity by coupling the film to a piezoelectric device sensitive to the pressure changes of the produced oxygen.