The Aspergillus nidulans kinesin-3 UncA motor moves vesicles along a subpopulation of microtubules.
The extremely polarized growth form of filamentous fungi imposes a huge challenge on the cellular transport machinery, because proteins and lipids required for hyphal extension need to be continuously transported to the growing tip. Recently, it was shown that endocytosis is also important for hyphal growth. Here, we found that the Aspergillus nidulans kinesin-3 motor protein UncA transports vesicles and is required for fast hyphal extension. Most surprisingly, UncA-dependent vesicle movement occurred along a subpopulation of microtubules. Green fluorescent protein (GFP)-labeled UncA(rigor) decorated a single microtubule, which remained intact during mitosis, whereas other cytoplasmic microtubules were depolymerized. Mitotic spindles were not labeled with GFP-UncA(rigor) but reacted with a specific antibody against tyrosinated alpha-tubulin. Hence, UncA binds preferentially to detyrosinated microtubules. In contrast, kinesin-1 (conventional kinesin) and kinesin-7 (KipA) did not show a preference for certain microtubules. This is the first example for different microtubule subpopulations in filamentous fungi and the first example for the preference of a kinesin-3 motor for detyrosinated microtubules.
Zekert
Nadine
N
University of Karlsruhe and Karlsruhe Institute of Technology, Institute of Applied Biosciences, Microbiology, D-76187 Karlsruhe, Germany.
Fischer
Reinhard
R
D001233:Aspergillus nidulans / Q000166:cytology / Q000378:metabolism; D001692:Biological Transport / Q000502:physiology; D022162:Cytoplasmic Vesicles / Q000378:metabolism; D005656:Fungal Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D025301:Hyphae / Q000378:metabolism / Q000648:ultrastructure; D016547:Kinesins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D008869:Microtubule-Associated Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*; D008954:Models, Biological; D020409:Molecular Motor Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010802:Phylogeny; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism
D005656:Fungal Proteins; D008869:Microtubule-Associated Proteins; D020409:Molecular Motor Proteins; D011993:Recombinant Fusion Proteins; D014443:Tyrosine; D016547:Kinesins