Assembly of silk-like proteins towards functional bio-inspired materials

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Volume Title

School of Chemical Technology | Doctoral thesis (article-based) | Defence date: 2024-10-18

Authors

Date

2024

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Mcode

Degree programme

Language

en

Pages

1,3-66,160

Series

Aalto University publication series DOCTORAL THESES, 187/2024

Abstract

Protein assembly plays a crucial role in the development of functional materials, leveraging the natural properties of proteins to create sophisticated, sustainable, and high-performance materials that meet the demands of diverse applications. Nature offers numerous examples of protein assembly into functional materials, such as silk and collagen. As a prevalent phenomenon in nature, liquid-liquid phase separation (LLPS) has been found involved in the organization and function of living cells and the formation of functional materials outside cells. LLPS is a process where certain mixtures undergo demixing, resulting in a solute-rich dense phase and a solute-poor dilute phase. The dense phase is often referred to as coacervates or condensates. LLPS has gained increasing attention for its significant implications for the design of biological materials. Understanding and exploiting the principles underlying protein assembly through LLPS are therefore important for the design and engineering of bioinspired materials in synthetic biosystems. This thesis work utilized recombinant silk-like proteins as the main building blocks and incorporated other components using the powerful SpyCatcher-SpyTag protein pair to develop strategies and provide insights for functional materials development through LLPS. Publication I investigated the role of coacervates and 3,4-dihydroxyphenylalanine (DOPA), two key features of marine mussel adhesion, on adhesion. This was achieved by incorporating silk-like proteins with mussel foot proteins, resulting in the development of a strong and tough adhesive. Publication II provided strategies for selective condensates that utilize the intrinsically disordered sequence derived from spider silk as a tag for recruiting client proteins into silk-like protein-based condensates. Publication III explored the effect of phosphate, an important element involved in spider silk formation, on silk-like proteins. This study revealed that phosphate induced β-sheet formation in silk-like proteins, stiffening the protein layers and reducing their ability to form new interactions, thereby impeding fiber formation for phosphate-induced coacervates. Publication IV further investigated the assemblies involved in LLPS for longer silk-like proteins and provided insights into the assembly pathway of these proteins. The results of this thesis provided strategies and insights for creating functional silk-like protein-based materials with specific properties, such as strong adhesives, selective condensates, and fibers. This research paves the way for future developments in biomaterials inspired by nature, highlighting the potential of protein-based materials in various applications.

Description

Supervising professor

Linder, Markus, Prof., Aalto University, Department of Bioproducts and Biosystems, Finland

Keywords

liquid-liquid phase separation, silk protein, mussel foot protein, SpyCatcher-SpyTag, adhesive, coacervate, condensate, fiber

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Parts

  • [Publication 1]: Yin, Yin; Roas-Escalona, Nelmary; Linder, Markus B. “Molecular Engineering of a Spider Silk and Mussel Foot Hybrid Protein Gives a Strong and Tough Biomimetic Adhesive.” Advanced Materials Interfaces, 11: 2300934 (2024).
    DOI: 10.1002/admi.202300934 View at publisher
  • [Publication 2]: Yin, Yin; Linder, Markus B. “Selective Protein Recruitment into Condensates Using Intrinsically Disordered Silk Repetitive Sequences.” Submitted manuscript to Soft Matter in the year 2024
  • [Publication 3]: Yin, Yin; Griffo, Alessandra; Cruz, Adrián Gutiérrez; Hähl, Hendrik; Jacobs, Karin; Linder, Markus B. “Effect of Phosphate on the Molecular Properties, Interactions, and Assembly of Engineered Spider Silk Proteins.” Biomacromolecules, 25: 3990–4000 (2024).
    DOI: 10.1021/acs.biomac.4c00115 View at publisher
  • [Publication 4]: Lemetti, Laura; Scacchi, Alberto; Yin, Yin; Shen, Mengjie; Linder, Markus B., Sammalkorpi, Maria; Aranko, A. Sesilja. “Liquid−Liquid Phase Separation and Assembly of Silk-like Proteins is Dependent on the Polymer Length.” Biomacromolecules, 23: 3142–3153 (2022).
    DOI: 10.1021/acs.biomac.2c00179 View at publisher

Citation