Two NDR kinase–MOB complexes function as distinct modules during septum formation and tip extension in Neurospora crassa

Abstract

Summary NDR kinases are important for growth and differentiation and require interaction with MOB proteins for activity and function. We characterized the NDR kinases and MOB activators in Neurospora crassa and identified two NDR kinases (COT1 and DBF2) and four MOB proteins (MOB1, MOB2A, MOB2B and MOB3/phocein) that form two functional NDR–MOB protein complexes. The MOB1–DBF2 complex is not only essential for septum formation in vegetative cells and during conidiation, but also functions during sexual fruiting body development and ascosporogenesis. The two MOB2-type proteins interact with both COT1 isoforms and control polar tip extension and branching by regulating COT1 activity. The conserved region directly preceding the kinase domain of COT1 is sufficient for the formation of COT1–MOB2 heterodimers, but also for kinase homodimerization. An additional N-terminal extension that is poorly conserved, but present in most fungal NDR kinases, is required for further stabilization of both types of interactions and for stimulating COT1 activity. COT1 lacking this region is degraded in a mob-2 background. We propose a specific role of MOB3/phocein during vegetative cell fusion, fruiting body development and ascosporogenesis that is unrelated to the three other MOB proteins and NDR kinase signalling.

The distinct wiring between cell cycle regulation and the widely conserved Morphogenesis-Related (MOR) pathway in the fungus Ustilago maydis determines the morphological outcome

“…Based on these sequence similarities, we assigned the names Mob1 to UM04352, Mob2 to UM12135, and Mob3 to UM00493. It is worth noting that in fungi, Mob2 homologs appeared to form two distinct clusters (Maerz et al, 2009). Homologs from filamentous fungi (N. crassa and A. nidulans) were clustered together, while homologs from yeast-like fungi were clustered in another group (Fig.…”

“…One group of NDR kinases is crucial for coordination between mitotic exit and septum formation as well as cell separation (Dbf2 group) while the other group controls polar cell morphology (Cot1 group) (Maerz et al, 2009). In U. maydis three NDR kinases can be identified by sequence analysis (supplementary material Fig.…”

“…The MOR pathway, also named the RAM (regulation of Ace2 and morphogenesis) pathway, is conserved among different fungi (Maerz and Seiler, 2010). This pathway includes a nuclear Dbf2-related (NDR) kinase termed Cbk1 in Saccharomyces cerevisiae (Racki et al, 2000), Orb6 in Schizosaccharomyces pombe (Verde et al, 1998), and COT1 in Neurospora crassa (Yarden et al, 1992), associated with a regulatory subunit, Mob2 (Hou et al, 2003;Maerz et al, 2009;Nelson et al, 2003). The NDR-Mob2 complex is activated by a germinal center kinase called Kic1 in S. cerevisiae (Nelson et al, 2003), Nak1 in S. pombe (Huang et al, 2003), and Pod6 in N. crassa (Seiler et al, 2006).…”

Early Colony Establishment in Neurospora crassa Requires a MAP Kinase Regulatory Network

“…By evaluating our expression data, 16 of these genes were dependent on PP1 for their expression (.1.5-fold lower in Δpp-1 as compared to WT, P , 0.05, RNA-seq data) (Table 3). This list included ham-7, Prm-1, ham-6, nox-1, nor-1, and adv-1, as well as 2 genes encoding kinases in the cellwall integrity pathway (mek-1 and mak-1) ; 2 genes encoding predicted components of the striatin complex (pp2A and mob-3) (Maerz et al 2009;Fu et al 2011); one transcription factor (rco-1) (Aldabbous et al 2010); genes for two GPI-anchored cell-wall proteins (gpip-2 and gpip-1) (Bowman et al 2006); ham-8, encoding a predicted transmembrane protein; ham-9, encoding a protein with pleckstrin homology domain and a sterile a-motif domain (Fu et al 2011); and so (Fleissner et al 2005). During germling fusion, SO also oscillates to CAT tips, with opposite dynamics to MAK2 (Fleissner et al 2009b); correct oscillation of SO requires MAK2 kinase activity.…”

A versatile set of Lifeact-RFP expression plasmids for live-cell imaging of F-actin in filamentous fungi

“…Therefore, pALxLifeact transformant selection with nourseothricin was the preferred option, as it is much more stringent than ignite per se and has no reported problems in conferring cross-resistance to other selection markers, such as hygromycin B (Kück and Hoff, 2006). Nourseothricin has been successfully used for the transformation of several yeast species including Saccharomyces cerevisiae (Goldstein and McCusker, 1999), Schizosaccharomyces pombe (Hentges et al, 2005), Candida albicans (Shen et al, 2005) and Cryptococcus neoformans (McDade and Cox, 2001), and more recently in an increasing number of filamentous fungal species, including Acremonium chrysogenum and Sordaria macrospora (Kück and Hoff, 2006), as well as Neurospora crassa (Maerz et al, 2009;Maerz et al, 2008).…”