19CK2, a serine/threonine (S/T) kinase present in eukaryotic cells is known to have a vast number of 20 substrates. We have recently shown that it localizes to nuclei and at pores between hyphal 21 compartments in M. oryzae. We performed a pulldown-proteomics of M. oryzae CK2 catalytic subunit 22 MoCKa to detect interacting proteins. The MoCKa pulldown was enriched for septa and nucleoli 23 proteins and intrinsically disordered proteins (IDPs) containing a CK2 phosphorylation motif proposed 24 to destabilize and unfold alpha helixes. This points to a function for CK2 phosphorylation and 25 corresponding phosphatase dephosphorylation in the formation of functional protein-protein aggregates 26 and protein-RNA/DNA binding. To test this as widely as possible we used secondary data downloaded 27 2 from databases from a large range of M. oryzae experiments and also for a relatively closely related 28 plant pathogenic fungus, Fusarium graminearum. We found that CKa expression was strongly 29 positively correlated with S/T phosphatases as well as with disaggregase (HSP104, YDJ1, SSA1) and 30 an autophagy indicating protein (ATG8). The latter points to increased protein aggregate formation at 31 high levels of CKa expression. Our results suggest a general role for CK2 in aggregation and 32 disaggregation of IDPs and their binding to proteins, DNA and RNA interactions. 33 34 35 36CK2 is a serine/threonine (S/T) kinase constitutively active in eukaryotes (Meggio and Pinna, 2003).
37The CK2 holoenzyme is a heterotetrameric structure consisting of two α-units and two regulatory β-38 subunits (Ahmad et al., 2008). In yeast these units can each be of two types and are named a1, a2, b1 39 and b2 (Padmanabha et al., 1990) while several other fungi, including M. oryzae, only contain one CKa 40 (Zhang et al., 2019). CK2 have been shown to phosphorylates a large number of proteins (Meggio and 41 Pinna, 2003;Ahmad et al., 2008;Götz and Montenarh, 2016) and seems involved in many cellular 42 processes (Götz and Montenarh, 2016). Interestingly, intrinsically highly disordered SRP40 protein in 43 yeast (homologous to Nopp140; Insect, Drosophila and Nolc1;Mammal, Human) has been shown to 44 become phosphorylated to varying degrees by CK2 with effects on the SRP40 conformation, binding, 45 and aggregation properties with further effects on the diverse functions of the protein (Tantos et al., 46 2013; Na et al., 2018). The large number of substrates of CK2, could possibly be explained if CK2 47To test this destabilization/unfolding hypothesis in a general way we decided to make an analysis of 64 secondary data already published (Smith et al., 2011;Zaritsky, 2018) and downloaded a large range of 65 transcriptomic data for M. oryzae. The following hypotheses resulting from the general hypothesis 66 were tested: Sub-hypothesis 1: If unfolding-refolding activity is important for IDP aggregation then a 67 high CKa expression should be correlated with expression of some S/T phosphatases present in the 68 pulldown that can act as a counte...