title: Aspergillus myosin-V supports polarized growth in the absence of microtubule-based transport.
abstract: In the filamentous fungus Aspergillus nidulans, both microtubules and actin filaments are important for polarized growth at the hyphal tip. Less clear is how different microtubule-based and actin-based motors work together to support this growth. Here we examined the role of myosin-V (MYOV) in hyphal growth. MYOV-depleted cells form elongated hyphae, but the rate of hyphal elongation is significantly reduced. In addition, although wild type cells without microtubules still undergo polarized growth, microtubule disassembly abolishes polarized growth in MYOV-depleted cells. Thus, MYOV is essential for polarized growth in the absence of microtubules. Moreover, while a triple kinesin null mutant lacking kinesin-1 (KINA) and two kinesin-3s (UNCA and UNCB) undergoes hyphal elongation and forms a colony, depleting MYOV in this triple mutant results in lethality due to a severe defect in polarized growth. These results argue that MYOV, through its ability to transport secretory cargo, can support a significant amount of polarized hyphal tip growth in the absence of any microtubule-based transport. Finally, our genetic analyses also indicate that KINA (kinesin-1) rather than UNCA (kinesin-3) is the major kinesin motor that supports polarized growth in the absence of MYOV.
authors.affiliation: Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, F. Edward Hébert School of Medicine, Bethesda, Maryland, United States of America.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang
authors.forename: Kaeling
authors.initials: K
authors.lastname: Tan
authors.forename: Xufeng
authors.initials: X
authors.lastname: Wu
authors.forename: Guifang
authors.initials: G
authors.lastname: Chen
authors.forename: Jinjin
authors.initials: J
authors.lastname: Sun
authors.forename: Samara L
authors.initials: SL
authors.lastname: Reck-Peterson
authors.forename: John A
authors.initials: JA
authors.lastname: Hammer
authors.forename: Xin
authors.initials: X
authors.lastname: Xiang
mesh_terms: D001233:Aspergillus nidulans / Q000166:cytology / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism*; D001542:Benomyl / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D016764:Cell Polarity / Q000187:drug effects; D049452:Green Fluorescent Proteins / Q000378:metabolism; D025301:Hyphae / Q000166:cytology / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D016547:Kinesins / Q000378:metabolism; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D024701:Myosin Type V / Q000378:metabolism*; D010641:Phenotype; D011993:Recombinant Fusion Proteins / Q000378:metabolism
chemical_list: D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D024701:Myosin Type V; D016547:Kinesins; D001542:Benomyl