Visiting Scientist Seminar – Professor Katja Salomon Johansen

Abstract

Lytic polysaccharide monooxygenases (LPMOs) are copper enzymes that operate in synergy with carbohydrate hydrolases. By initiating degradation of recalcitrant substrates such as cellulose, these enzymes are major contributors to the recycling of carbon in nature. They are also being used in the biorefinery industry. We have studied LPMO reactions in complex saccharification trials using steam pre-treated wheat straw as substrate. Most recently, we have studied the role the CEL1 gene in the human fungal pathogen Cryptococcus neoformans is predicted by sequence homology to encode an LPMO of the AA9 enzyme family. The CEL1 gene is induced by host physiological pH and temperature, and it is primarily localized to the fungal cell wall. Targeted mutation of the CEL1 gene revealed that it is required for the expression of stress response phenotypes, including thermotolerance, cell wall integrity, and efficient cell cycle progression. Accordingly, a cel1Δ deletion mutant was avirulent in two models of C. neoformans infection. These and other recent findings in the field of LPMOs will be presented.

About the speaker

I am currently professor of plant cell wall degrading enzymes at Department of Geosciences, and Natural Resource Management (IGN) at University of Copenhagen. My masters and PhD degrees are both from the same university. However, I have worked in industrial R&D until 2015. While in the industry, I spearheaded the scientific activities around discovery and characterisation of a new class of oxidoreductases, now called LPMOs. I submitted a higher doctoral thesis describing this work to University of Copenhagen and received the D.Sc. in 2018. My research group focuses on enzymes for plant cell wall degradation and our work is funded by large grants from the Novo Nordisk Fonden. My postdoctoral work was carried out here in Adelaide in Geoff Fincher’s group and I passed by in 2020 (just before the pandemic) and gave a talk. I have been invited to talk at the local ICBIC conference. That presentation will focus on the reactivity of the mononuclear copper at the active site of LPMOs.

Webinar link – https://adelaide.zoom.us/webinar/register/WN_9Ca44q4JQlye0RMJ3SM3RQ