Cytoplasmic Dynein ATPase Activity Is Regulated by Dynactin-dependent Phosphorylation

• Published in: The Journal of biological chemistry Vol. 275; no. 41; pp. 31798 - 31804
• Main Authors: Kumar, Santosh, Lee, In Hyung, Plamann, Michael
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 13.10.2000; American Society for Biochemistry and Molecular Biology
• Subjects: Adenosine Triphosphate - metabolism; Adenosine Triphosphate - pharmacology; Animals; Brain; Cattle; Centrifugation, Density Gradient; Cytoplasm - enzymology; Cytoplasm - metabolism; Dynactin Complex; Dyneins - genetics; Dyneins - metabolism; Enzyme Activation; Fungal Proteins - genetics; Fungal Proteins - metabolism; Kinetics; Microtubule-Associated Proteins - genetics; Microtubule-Associated Proteins - metabolism; Microtubules - metabolism; Molecular Sequence Data; Molecular Weight; Mutation; Neurospora crassa - enzymology; Neurospora crassa - genetics; Phosphorylation; Precipitin Tests; Protein Binding - drug effects; Protein Tyrosine Phosphatases - metabolism; Receptor-Like Protein Tyrosine Phosphatases, Class 2
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M000449200

Cytoplasmic dynein is a microtubule-associated motor that utilizes ATP hydrolysis to conduct minus-end directed transport of various organelles. Dynactin is a multisubunit complex that has been proposed to both link dynein with cargo and activate dynein motor function. The mechanisms by which dynactin regulates dynein activity are not clear. In this study, we examine the role of dynactin in regulating dynein ATPase activity. We show that dynein-microtubule binding and ATP-dependent release of dynein from microtubules are reduced in dynactin null mutants, Δro-3 (p150Glued) and Δro-4(Arp1), relative to wild-type. The dynein-microtubule binding activity, but not the ATP-dependent release of dynein from microtubules, is restored by in vitro mixing of extracts from dynein and dynactin mutants. Dynein produced in a Δro-3 mutant has ∼8-fold reduced ATPase activity relative to dynein isolated from wild-type. However, dynein ATPase activity from wild-type is not reduced when dynactin is separated from dynein, suggesting that dynein produced in a dynactin mutant is inactivated. Treatment of dynein isolated from the Δro-3mutant with λ protein phosphatase restores the ATPase activity to near wild-type levels. The reduced dynein ATPase activity observed in dynactin null mutants is mainly due to altered affinity for ATP. Radiolabeling experiments revealed that low molecular mass proteins, particularly 20- and 8-kDa proteins, that immunoprecipitate with dynein heavy chain are hyperphosphorylated in the dynactin mutant and dephosphorylated upon λ protein phosphatase treatment. The results suggest that cytoplasmic dynein ATPase activity is regulated by dynactin-dependent phosphorylation of dynein light chains.