Insights into the action of phylogenetically diverse microbial expansins on the structure of cellulose microfibrils

Beskrivning

Abstract Background Microbial expansins (EXLXs) are non-lytic proteins homologous to plant expansins involved in plant cell wall formation. Due to their non-lytic cell wall loosening properties and potential to disaggregate cellulosic structures, there is considerable interest in exploring the ability of microbial expansins (EXLX) to assist the processing of cellulosic biomass for broader biotechnological applications. Herein, EXLXs with different modular structure and from diverse phylogenetic origin were compared in terms of ability to bind cellulosic, xylosic, and chitinous substrates, to structurally modify cellulosic fibrils, and to boost enzymatic deconstruction of hardwood pulp. Results Five heterogeneously produced EXLXs (Clavibacter michiganensis; CmiEXLX2, Dickeya aquatica; DaqEXLX1, Xanthomonas sacchari; XsaEXLX1, Nothophytophthora sp.; NspEXLX1 and Phytophthora cactorum; PcaEXLX1) were shown to bind xylan and hardwood pulp at pH 5.5 and CmiEXLX2 (harboring a family-2 carbohydrate-binding module) also bound well to crystalline cellulose. Small-angle X-ray scattering revealed a 20–25% increase in interfibrillar distance between neighboring cellulose microfibrils following treatment with CmiEXLX2, DaqEXLX1, or NspEXLX1. Correspondingly, combining xylanase with CmiEXLX2 and DaqEXLX1 increased product yield from hardwood pulp by ~ 25%, while supplementing the TrAA9A LPMO from Trichoderma reesei with CmiEXLX2, DaqEXLX1, and NspEXLX1 increased total product yield by over 35%. Conclusion This direct comparison of diverse EXLXs revealed consistent impacts on interfibrillar spacing of cellulose microfibers and performance of carbohydrate-active enzymes predicted to act on fiber surfaces. These findings uncover new possibilities to employ EXLXs in the creation of value-added materials from cellulosic biomass.
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Publiceringsår

2024

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Upphovspersoner

Department of Bioproducts and Biosystems

Aleksi Zitting Orcid -palvelun logo - Upphovsperson

Anu Koivula - Upphovsperson

Emma R. Master Orcid -palvelun logo - Upphovsperson

Garry W. Buchko - Upphovsperson

Janak Sapkota - Upphovsperson

Kaisa Marjamaa - Upphovsperson

Majid Haddad Momeni - Upphovsperson

Natalia Maiorova - Upphovsperson

Paavo Penttilä Orcid -palvelun logo - Upphovsperson

Rosaliina Turunen - Upphovsperson

Salla Hiltunen - Upphovsperson

Vilma Jäämuru - Upphovsperson

University of Toronto - Medarbetare

VTT Technical Research Centre of Finland Ltd. - Medarbetare

Washington State University - Medarbetare

figshare - Utgivare

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Övriga uppgifter

Vetenskapsområden

Biokemi, cell- och molekylärbiologi

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Creative Commons Attribution 4.0 International (CC BY 4.0)

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