Conserved Eukaryotic Kinase CK2 Chaperone Intrinsically Disordered Protein Interactions

Abstract

CK2, a serine/threonine (Ser/Thr) kinase present in eukaryotic cells, is known to have a vast number of substrates. We have recently shown that it localizes to nuclei and at pores between hyphal compartments in Magnaporthe oryzae. We performed a pulldown proteomics analysis of M. oryzae CK2 catalytic subunit MoCKa to detect interacting proteins. The MoCKa pulldown was enriched for septum and nucleolus proteins and intrinsically disordered proteins (IDPs) containing a CK2 phosphorylation motif that is proposed to destabilize and unfold α-helices. This points to a function for CK2 phosphorylation and corresponding phosphatase dephosphorylation in the formation of functional protein-protein aggregates and protein-RNA/DNA binding. To test this as widely as possible, we used secondary data downloaded from databases from a large range of M. oryzae experiments, as well as data for a relatively closely related plant-pathogenic fungus, Fusarium graminearum. We found that CKa expression was strongly positively correlated with Ser/Thr phosphatases, as well as with disaggregases (HSP104, YDJ1, and SSA1) and an autophagy-indicating protein (ATG8). The latter points to increased protein aggregate formation at high levels of CKa expression. Our results suggest a general role for CK2 in chaperoning aggregation and disaggregation of IDPs and their binding to proteins, DNA, and RNA. IMPORTANCE CK2 is a eukaryotic conserved kinase enzyme complex that phosphorylates proteins. CK2 is known to phosphorylate a large number of proteins and is constitutively active, and thus a “normal” role for a kinase in a signaling cascade might not be the case for CK2. Previous results on localization and indications from the literature point to a function for CK2 phosphorylation in shaping and folding of proteins, especially intrinsically disordered proteins, which constitute about 30% of eukaryotic proteins. We used pulldown of interacting proteins and data downloaded from a large range of transcriptomic experiments in M. oryzae and complemented these with data downloaded from a large range of transcriptomic experiments in Fusarium graminearum. We found support for a general role for CK2 in aggregation and disaggregation of IDPs and their binding to proteins, DNA, and RNA—interactions that could explain the importance of CK2 in eukaryotic cell function and disease.

Evolutionary conserved multifunctional nitric oxide synthesis proteins responding to bacterial MAMPs are located at the endoplasmic reticulum

“…We have previously downloaded publicly available transcriptomic in planta data from plant infection plant infection experiments (Zhang et al ., 2019). Especially the first dataset from a time course of infection is interesting since deletion of FgNCP NO completely stopped DON production ( Fig.…”

Use of Ecologically-and Evolutionary Relevant Transcriptomic Data to Infer Functions of Fungal Pathogen Gene Orthologs Important for Limiting Fungal Stresses Caused by Interacting Host Plants and Bacteria

“…At the end of the necrotrophic phase both fungi switch from biomass growth to conidia production emptying the vegetative mycelium of biomass to form conidia that can spread to other plants and infect them. In a previous study we found that the expression of the key autophagy gene ATG8 increases with HPI in both fungi and can be used as indicator for hours post infection (HPI) in the downloaded expression data from a large number of experiments [10]. In the same study we identified the His2b gene as an indicator of de novo DNA synthesis and growth since free histones not bound to DNA are cytotoxic [10,11].…”

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