Governing fungal polar cell extension:: Analysis of Rho GTPase and NDR kinase signalling in Neurospora crassa

摘要: Polar morphogenesis is required for the function of elongated cell types like neuronal cells, pollen tubes and cells filamentous fungi. The basal signalling components involved are highly conserved. Defects in polar shape can result developmental disorders or death the affected cell. In this work two components involved growth were analysed at a molecular level Neurospora crassa. These LRG1, which a member GTPase activating proteins (GAPs), and the germinal center kinase POD6.POD6 LRG1 essential hyphal tip elongation. Deletion temperature sensitive mutants of pod-6 lrg-1 show phenotypic similarities to cot-1 mutant cessation hyphal elongation excessive hyperbranching. All three are also determining size compartments. Complementation analysis revealed that both parts, N-terminal containing LIM domains as well C-terminal harbouring the Rho GAP domain LRG1, its function. Genetic evidence vitro assays identify as a RHO1 specific GAP. Localisation experiments partial colocalisation of POD6 COT1 depends on oppositely directed microtubule motor kinesin-1 dynein. shows a similar localisation enriched at septae hyphal tips. This was observed by immunofluorescence studies with antibodies generated against confirmed strain expressing MYC9::LRG1. In strains expressing GFP::LRG1, dynamic accumulation fusion protein an apical cap observed. This LRG1, a functional actin cytoskeleton active growth. Similar to the localisation POD6, is influenced dynein microtubule cytoskeleton. affects several output pathways RHO1. Hyposensitivity lrg-1(12-20) glucan synthase inhibitor caspofungin synthetic lethality with hyperactive s1,3-glucan synthase occurred. Further, suppression PKC inhibitors staurosporine cercosporamide observed. Hypersensitivity depolymerising drug latrunculin A and the defects the overexpression dominant-negative acting N-terminus the formin BNI1 indicate influence formin mediated actin polymerisation. contrast, cot-1 mutation has no influence regarding these effectors. Taken together, these data suggest functions Rho1 that regulates effector pathways. complex and POD6 acts parallel coordinate tip