Coupling of ATPase activity, microtubule binding, and mechanics in the dynein motor domain

• Stefan Niekamp ^[3] ; Nicolas Coudray ^[4] ; Nan Zhang ^[1] ; Ronald D Vale ^[1] ; Gira Bhabha ^[2]
  1. [1] Howard Hughes Medical Institute

     Howard Hughes Medical Institute

     Estados Unidos

     
  2. [2] New York University

     New York University

     Estados Unidos

     
  3. [3] Medical InstituteUniversity of California San FranciscoSan FranciscoCAUSA
  4. [4] Skirball Institute of Biomolecular Medicine New York University School of MedicineNew York

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• Localización: EMBO journal: European Molecular Biology Organization, ISSN 0261-4189, Vol. 38, Nº. 13, 2019
• Idioma: inglés
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• Resumen

  • The movement of a molecular motor protein along a cytoskeletal track requires communication between enzymatic, polymer‐binding, and mechanical elements. Such communication is particularly complex and not well understood in the dynein motor, an ATPase that is comprised of a ring of six AAA domains, a large mechanical element (linker) spanning over the ring, and a microtubule‐binding domain (MTBD) that is separated from the AAA ring by a ~ 135 Å coiled‐coil stalk. We identified mutations in the stalk that disrupt directional motion, have microtubule‐independent hyperactive ATPase activity, and nucleotide‐independent low affinity for microtubules. Cryo‐electron microscopy structures of a mutant that uncouples ATPase activity from directional movement reveal that nucleotide‐dependent conformational changes occur normally in one‐half of the AAA ring, but are disrupted in the other half. The large‐scale linker conformational change observed in the wild‐type protein is also inhibited, revealing that this conformational change is not required for ATP hydrolysis. These results demonstrate an essential role of the stalk in regulating motor activity and coupling conformational changes across the two halves of the AAA ring.