Genetic evidence for a microtubule-capture mechanism during polarised growth of Aspergillus nidulans.
The cellular switch from symmetry to polarity in eukaryotes depends on the microtubule (MT) and actin cytoskeletons. In fungi such as Schizosaccharomyces pombe or Aspergillus nidulans, the MT cytoskeleton determines the sites of actin polymerization through cortical cell-end marker proteins. Here we describe A. nidulans MT guidance protein A (MigA) as the first ortholog of the karyogamy protein Kar9 from Saccharomyces cerevisiae in filamentous fungi. A. nidulans MigA interacts with the cortical ApsA protein and is involved in spindle positioning during mitosis. MigA is also associated with septal and nuclear MT organizing centers (MTOCs). Super-resolution photoactivated localization microscopy (PALM) analyses revealed that MigA is recruited to assembling and retracting MT plus ends in an EbA-dependent manner. MigA is required for MT convergence in hyphal tips and plays a role in correct localization of the cell-end markers TeaA and TeaR. In addition, MigA interacts with a class-V myosin, suggesting that an active mechanism exists to capture MTs and to pull the ends along actin filaments. Hence, the organization of MTs and actin depend on each other, and positive feedback loops ensure robust polar growth.
Karlsruhe Institute of Technology (KIT) - South Campus, Institute for Applied Biosciences, Department of Microbiology, Hertzstrasse 16, Karlsruhe D-76187, Germany.
Raphael
R
Manck
Karlsruhe Institute of Technology (KIT) - South Campus, Institute for Applied Physics and Center for Functional Nanostructures, Karlsruhe 76131, Germany.
Yuji
Y
Ishitsuka
Karlsruhe Institute of Technology (KIT) - South Campus, Institute for Applied Biosciences, Department of Microbiology, Hertzstrasse 16, Karlsruhe D-76187, Germany.
Saturnino
S
Herrero
Karlsruhe Institute of Technology (KIT) - South Campus, Institute for Applied Biosciences, Department of Microbiology, Hertzstrasse 16, Karlsruhe D-76187, Germany University of Tsukuba, Faculty of Life and Environmental Sciences, Tsukuba, Ibaraki 305-8572, Japan.
Norio
N
Takeshita
Karlsruhe Institute of Technology (KIT) - South Campus, Institute for Applied Physics and Center for Functional Nanostructures, Karlsruhe 76131, Germany.
G Ulrich
GU
Nienhaus
Karlsruhe Institute of Technology (KIT) - South Campus, Institute for Applied Biosciences, Department of Microbiology, Hertzstrasse 16, Karlsruhe D-76187, Germany reinhard.fischer@kit.edu.
Reinhard
R
Fischer
D001233:Aspergillus nidulans / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D004398:Dyneins / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D022101:Microtubule-Organizing Center / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism
D005656:Fungal Proteins; D004398:Dyneins
APC; Aspergillus; Dynein; Kar9; Polarity