Department of Bioproducts and Biosystems

Protein engineering

The Protein engineering group, led by Senior Scientist Sesilja Aranko, aims to expand the repertoire of enzymes that catalyze protein modifications. We develop methods for biomolecular protein-conjugation reactions as well as enzymatic post-translational modifications, including phosphorylations, hydroxylations and glycosylations. The applications of the research range from protein- and peptide-purification technologies to functionalization, texturing and crosslinking. We are particularly interested in modifying proteins relevant for biomaterials, including silk- and collagen-proteins, with the aim of developing novel sustainable yet high-performing biomaterials.
Protein kinase 3D model
Image: Sesilja Aranko

Research themes

  • Protein ligases 
  • Kinases, hydroxylases and glycosyltransferases 
  • Folding and assembly mechanisms of silk and collagen proteins 
Assembly: Sesilja Aranko. Collagen protein and film, fluorescent silk protein, silk fibers
Composite image: Sesilja Aranko

Examples of ongoing research projects

Functional and water-resistant composite materials from crosslinked non-canonical silks and cellulose (CrossSilk)

In this project, funded by the Research Council of Finland (formerly the Academy of Finland), we aim to improve the water resistance of currently available silk- and cellulose-based biomaterials by mimicking the crosslinking of natural silks and leather. The goal is to design fully biodegradable materials with outstanding mechanical properties in both dry and wet states. We hope that the novel crosslinked silk-CNF composite materials developed in the project can be used as a renewable and biodegradable alternative to replace current plastic- and animal-based materials.

From post-translationally modified proteins to functional biomaterials (Pro2Fun)

The goal of this project, funded by the Novo Nordisk Foundation Emerging Investigator grant, is to develop methods to produce post-translationally modified structural proteins, including silks and collagens, in bacteria that cannot make the desired modifications naturally. There is accumulating evidence that the post-translational modifications of proteins are essential for the mechanical properties and functionalities of the resulting materials. Yet, the mechanisms behind how these modifications affect the properties of biomaterials are not fully understood, mainly due to technical limitations. Production in bacteria enables obtaining the proteins in an economical, ethical, and sustainable manner. We use the modified proteins to engineer novel functional biomaterials, which have the potential to substitute current oil- and animal-based alternatives.

Group members

 Sesilja Aranko

Sesilja Aranko

Senior Scientist
T107 Bioproducts and Biosystems
 Nea Möttönen

Nea Möttönen

Master's student

Stefania Aspholm-Tsironi

Master's student

Katarina Knuuttila

Research assistant
 Oguzcan Ates

Oguzcan Ates

Master's student

Interested in joining us? 

Contact: [email protected]


Biomolecular Click Reactions Using a Minimal pH-Activated Catcher/Tag Pair for Producing Native-Sized Spider-Silk Proteins

Ruxia Fan, Johanna Hakanpää, Karoliina Elfving, Helena Taberman, Markus B. Linder, A. Sesilja Aranko 2023

Upcycling of Keratin Wastes in Sustainable Textile Fiber Applications

Wenwen Fang, Ruxia Fan, A. Sesilja Aranko, Michael Hummel, Herbert Sixta 2023

Triblock Proteins with Weakly Dimerizing Terminal Blocks and an Intrinsically Disordered Region for Rational Design of Condensate Properties

Dmitrii Fedorov, Nelmary Roas-Escalona, Dmitry Tolmachev, Adam L. Harmat, Alberto Scacchi, Maria Sammalkorpi, A. Sesilja Aranko, Markus B. Linder 2023

Molecular mechanisms mediating stiffening in the mechanically adaptable connective tissues of sea cucumbers

Marie Bonneel, Elise Hennebert, A. Sesilja Aranko, Dong Soo Hwang, Mathilde Lefevre, Valentine Pommier, Ruddy Wattiez, Jérôme Delroisse, Patrick Flammang 2022

Liquid-Liquid Phase Separation and Assembly of Silk-like Proteins is Dependent on the Polymer Length

Laura Lemetti, Alberto Scacchi, Yin Yin, Mengjie Shen, Markus B. Linder, Maria Sammalkorpi, A. Sesilja Aranko 2022

Recombinant Spider Silk Protein and Delignified Wood Form a Strong Adhesive System

Laura Lemetti, Jennifer Tersteegen, Juuso Sammaljärvi, A. Sesilja Aranko, Markus B. Linder 2022

The Convergence of the Hedgehog/Intein Fold in Different Protein Splicing Mechanisms

Hannes M. Beyer, Salla I. Virtanen, A. Sesilja Aranko, Kornelia M. Mikula, George T. Lountos, Alexander Wlodawer, O. H.Samuli Ollila, Hideo Iwaï 2020

Sea star-inspired recombinant adhesive proteins self-assemble and adsorb on surfaces in aqueous environments to form cytocompatible coatings

Mathilde Lefevre, Patrick Flammang, A. Sesilja Aranko, Markus B. Linder, Thomas Scheibel, Martin Humenik, Maxime Leclercq, Mathieu Surin, Lionel Tafforeau, Ruddy Wattiez, Philippe Leclère, Elise Hennebert 2020

Substrate specificities of inteins investigated by QuickDrop-cassette mutagenesis

Jesper S. Oeemig, Hannes M. Beyer, A. Sesilja Aranko, Justus Mutanen, Hideo Iwaï 2020

Molecular crowding facilitates assembly of spidroin-like proteins through phase separation

Laura Lemetti, Sami Pekka Hirvonen, Dmitrii Fedorov, Piotr Batys, Maria Sammalkorpi, Heikki Tenhu, Markus B. Linder, A. Sesilja Aranko 2019

Biomimetic composites with enhanced toughening using silk-inspired triblock proteins and aligned nanocellulose reinforcements

Pezhman Mohammadi, A. Sesilja Aranko, Christopher P. Landowski, Olli Ikkala, Kristaps Jaudzems, Wolfgang Wagermaier, Markus B. Linder 2019

Phase transitions as intermediate steps in the formation of molecularly engineered protein fibers

Pezhman Mohammadi, Aino Sesilja Aranko, Laura Lemetti, Zoran Cenev, Quan Zhou, Salla Virtanen, Christopher P. Landowski, Merja Penttilä, Wolfgang J. Fischer, Wolfgang Wagermaier, Markus Linder 2018

Nature's recipe for splitting inteins

Aino Sesilja Aranko, Alexander Wlodawer, Hideo Iwaï 2014

Structure-based engineering and comparison of novel split inteins for protein ligation

A. Sesilja Aranko, Jesper S. Oeemig, Dongwen Zhou, Tommi Kajander, Alexander Wlodawer, Hideo Iwaï 2014

Intermolecular domain swapping induces intein-mediated protein alternative splicing

Sesilja Aranko, Jesper S. Oeemig, Tommi Kajander, Hideo Iwaï 2013

Use of protein trans-splicing to produce active and segmentally 2H, 15N labeled mannuronan C5-epimerase AlgE4

Edith Buchinger, Finn L. Aachmann, Sesilja Aranko, Svein Valla, Gudmund Skjåk-BræK, Hideo Iwaï, Reinhard Wimmer 2010

In vivo and in vitro protein ligation by naturally occurring and engineered split DnaE inteins

A. Sesilja Aranko, Sara Züger, Edith Buchinger, Hideo Iwaï 2009

Segmental isotopic labeling of a central domain in a multidomain protein by protein traws-splicing using only one robust dnae intein

Alena E L Busche, Sesilja Aranko, Mehdi Talebzadeh-Farooji, Frank Bernhard, Volker Dötsch, Hideo Iwaï 2009

Solution structure of DnaE intein from Nostoc punctiforme

Jesper S. Oeemig, Sesilja Aranko, Janica Djupsjöbacka, Kimmo Heinämäki, Hideo Iwaï 2009
More information on our research in the Aalto research portal.
Research portal

Infrastructure we use

Opening of the Aalto Bioproduct Centre

Bioeconomy Infrastructure (external link)

Joint research infrastructure of Aalto University and VTT Bioeconomy infrastructure on Finland’s roadmap for research infrastructures 2021–2024

Kvanttibitit. Kuva: Jan Goetz.


OtaNano is Finland's national research infrastructure for micro-, nano-, and quantum technologies

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European Molecular Biology Laboratory (external link)

With 28 member states, EMBL has more than 110 independent research groups and service teams covering the spectrum of molecular biology at six sites in Barcelona, Grenoble, Hamburg, Heidelberg, EMBL-EBI Hinxton, and Rome.

Sesilja Aranko.

Considerable Novo Nordisk funding for researcher Sesilja Aranko

Staff Scientist Sesilja Aranko has been awarded the highly competed Emerging Investigator 2023 Grant from Novo Nordisk Foundation for a research project focusing on post-translational modifications in protein-based biomaterials. The grant awarded is 10 million DKK (approx. 1.34M€) for a five-year period.

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