Arp11 affects dynein-dynactin interaction and is essential for dynein function in Aspergillus nidulans.
The dynactin complex contains proteins including p150 that interacts with cytoplasmic dynein and an actin-related protein Arp1 that forms a minifilament. Proteins including Arp11 and p62 locate at the pointed end of the Arp1 filament, but their biochemical functions are unclear (Schroer TA. Dynactin. Annu Rev Cell Dev Biol 2004;20:759-779). In Aspergillus nidulans, loss of Arp11 or p62 causes the same nuclear distribution (nud) defect displayed by dynein mutants, indicating that these pointed-end proteins are essential for dynein function. We constructed a strain with S-tagged p150 of dynactin that allows us to pull down components of the dynactin and dynein complexes. Surprisingly, while the ratio of pulled-down Arp1 to S-p150 in Arp11-depleted cells is clearly lower than that in wild-type cells, the ratio of pulled-down dynein to S-p150 is significantly higher. We further show that the enhanced dynein-dynactin interaction in Arp11-depleted cells is also present in the soluble fraction and therefore is not dependent upon the affinity of these proteins to the membrane. We suggest that loss of the pointed-end proteins alters the Arp1 filament in a way that affects the conformation of p150 required for its proper interaction with the dynein motor.
Zhang
Jun
J
Department of Biochemistry and Molecular Biology, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA.
Wang
Liqin
L
Zhuang
Lei
L
Huo
Liang
L
Musa
Shamsideen
S
Li
Shihe
S
Xiang
Xin
X
D051378:Actin-Related Protein 3 / Q000378:metabolism*; D000483:Alleles; D001233:Aspergillus nidulans / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D000072159:Dynactin Complex; D004398:Dyneins / Q000737:chemistry*; D005656:Fungal Proteins / Q000378:metabolism; D005816:Genetic Complementation Test; D016681:Genome, Fungal; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008840:Microfilament Proteins / Q000737:chemistry / Q000502:physiology*; D008869:Microtubule-Associated Proteins / Q000737:chemistry*; D009154:Mutation; D010641:Phenotype; D011485:Protein Binding; D014461:Ultracentrifugation
D051378:Actin-Related Protein 3; D000072159:Dynactin Complex; D005656:Fungal Proteins; D008840:Microfilament Proteins; D008869:Microtubule-Associated Proteins; D049452:Green Fluorescent Proteins; D004247:DNA; D004398:Dyneins