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bioRxiv · 10.1101/2023.01.16.524192

Mechanistic insights into the role of Ca2+-stimulated AMPK in the secretion of cellulases during carbon stress

Randhawa, A.·Sinha, T.·Das, M.·Ogunyewo, O. A.·Jawed, K.·Yazdani, S. S.
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Abstract

The response of filamentous fungi towards recalcitrant carbohydrates is majorly governed by transcriptional activators of cellulase genes; however, little is known about the downstream events beyond transcription. We show here in Penicillium funiculosum that increasing the expression of a transcriptional activator CLR-2 in the catabolically derepressed strain, {Delta}Mig1, didnt exhibit a synergistic effect on cellulase production unless Ca2+ was simultaneously increased. The RNA-seq screen for Ca2+-activated kinases identified SNF1-AMPK and SSP1-AMPKK as being specific to cellulose induction. Deletion of snf1 led to negligible secretion of cellulase upon induction. Quantitative whole-cell proteomics followed by chemical-genetic experiments with snf1-deleted strain showed that Ca2+-signaling channelizes carbon, nitrogen and energy sources towards cellulase production. Further, Ca2+-signaling phosphorylates SNF1-AMPK via SSP1, which in turn downregulates the phospho-HOG1 levels, leading to stimulus for cellulase secretion during carbon stress. The findings reported here are significant for understanding fungal pathology and developing second-generation biorefineries.

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Randhawa, A., Sinha, T., Das, M., Ogunyewo, O. A., Jawed, K., Yazdani, S. S.. 2023-01-17. Mechanistic insights into the role of Ca2+-stimulated AMPK in the secretion of cellulases during carbon stress. https://doi.org/10.1101/2023.01.16.524192

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