title: Dynein light intermediate chain in Aspergillus nidulans is essential for the interaction between heavy and intermediate chains.
abstract: Cytoplasmic dynein is a complex containing heavy chains (HCs), intermediate chains (ICs), light intermediate chains (LICs), and light chains (LCs). The HCs are responsible for motor activity. The ICs at the tail region of the motor interact with dynactin, which is essential for dynein function. However, functions of other subunits and how they contribute to the assembly of the core complex are not clearly defined. Here, we analyzed in the filamentous fungus Aspergillus nidulans functions of the only LIC and two LCs, RobA (Roadblock/LC7) and TctexA (Tctex1) in dynein-mediated nuclear distribution (nud). Whereas the deletion mutant of tctexA did not exhibit an apparent nud mutant phenotype, the deletion mutant of robA exhibited a nud phenotype at an elevated temperature, which is similar to the previously characterized nudG (LC8) deletion mutant. Remarkably, in contrast to the single mutants, the robA and nudG double deletion mutant exhibits a severe nud phenotype at various temperatures. Thus, functions of these two LC classes overlap to some extent, but the presence of both becomes important under specific conditions. The single LIC, however, is essential for dynein function in nuclear distribution. This is evidenced by the identification of the nudN gene as the LIC coding gene, and by the nud phenotype exhibited by the LIC down-regulating mutant, alcA-LIC. Without a functional LIC, the HC-IC association is significantly weakened, and the HCs could no longer accumulate at the microtubule plus end. Thus, the LIC is essential for the assembly of the core complex of dynein in Aspergillus.
authors.affiliation: From the Department of Biochemistry and Molecular Biology, The Uniformed Services University of the Health Sciences-F. Edward Hébert School of Medicine, Bethesda, Maryland 20814, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang
authors.forename: Shihe
authors.initials: S
authors.lastname: Li
authors.forename: Shamsideen
authors.initials: S
authors.lastname: Musa
authors.forename: Henry
authors.initials: H
authors.lastname: Zhou
authors.forename: Xin
authors.initials: X
authors.lastname: Xiang
mesh_terms: D000818:Animals; D001233:Aspergillus nidulans / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D004398:Dyneins / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D011993:Recombinant Fusion Proteins; D004398:Dyneins