Tracks for traffic: microtubules in the plant pathogen Ustilago maydis.
Pathogenic development of the corn smut fungus Ustilago maydis depends on the ability of the hypha to grow invasively. Extended hyphal growth and mitosis require microtubules, as revealed by recent studies on the microtubule cytoskeleton. Surprisingly, hyphal tip growth involves only two out of 10 kinesins. Kinesin-3 is responsible for tip-directed (anterograde) endosome motility of early endosomes, which are thought to support hyphal elongation by apical membrane recycling. In addition, kinesin-3, together with kinesin-1 and myosin-5, appear to deliver secretory vesicles to the hyphal tip. Kinesin-1 also affects endosome motility by targeting cytoplasmic dynein to microtubule plus ends. This plus-end localization of dynein is essential for cell body-directed (retrograde) endosome motility, but also allows force generation during spindle elongation in mitosis. Furthermore, kinesin-1 and dynein participate in the organization of the microtubule array, thereby building their own network of tracks for intracellular motility. The recent progress in understanding microtubule-based processes in U. maydis has revealed an unexpected complexity of motor functions essential for the virulence of this pathogen. Further studies on structural and regulatory requirements for motor activity should help identify novel targets for fungicide development.
Steinberg
Gero
G
Max-Planck-Institut für terrestrische Mikrobiologie, Karl-von-Frisch-Straße, D-35043 Marburg, Germany.
D016547:Kinesins / Q000502:physiology; D008870:Microtubules / Q000648:ultrastructure*; D008938:Mitosis; D009685:Nuclear Envelope / Q000648:ultrastructure; D010935:Plant Diseases / Q000382:microbiology*; D010944:Plants / Q000382:microbiology*; D014588:Ustilago / Q000166:cytology / Q000254:growth & development / Q000472:pathogenicity* / Q000648:ultrastructure*
D016547:Kinesins