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Motor proteins are the freight trains of the cell, transporting large molecular cargo from one location to another using an array of ‘roads’ known as microtubules. These hollow tubes are oriented, with one extremity (the plus-end) growing faster than the other (the minus-end). While over 40 different motor proteins travel towards the plus-end of microtubules, just one is responsible for moving cargo in the opposite direction. This protein, called dynein, performs a wide range of functions which must be carefully regulated, often through changes in the shape and interactions of various dynein segments. The intermediate chain is one of the essential subunits that form dynein, and it acts as a binding site for a range of molecular actors. In particular, it connects the three other dynein subunits (known as the light chains) to the dynein heavy chain containing the motor domain. It also binds to two non-dynein proteins: NudE, which helps to organise microtubules, and the p150 Glued region of dynactin, a protein required for dynein activity. Despite their distinct roles, p150 Glued and NudE attach to the same region of the intermediate chain, a highly flexible ‘unstructured’ segment which is difficult to study. How the binding of p150 Glued and NudE is regulated has therefore remained unsolved. In response, Jara et al. decided to investigate how the three dynein light chains may help to control interactions between the intermediate chain and non-dynein proteins. They used more stable versions of dynein, NudE and dynactin (from a fungus that grows at high temperatures) to produce the various subcomplexes formed by the intermediate chain, the three dynein light chains, and parts of p150 Glued and NudE. A suite of biophysical techniques was applied to study these structures, as they are challenging to capture using traditional approaches. This revealed that the unstructured region of the intermediate chain can fold back on itself, bringing together its two extremities; such folding blocks the p150 Glued and NudE binding site. This obstruction is cleared when the light chains bind to the intermediate chain, demonstrating how these three subunits can regulate dynein activity. In humans, mutations in dynein are associated with a range of serious neurological and muscular diseases. The work by Jara et al. brings new insight into the way this protein works; more importantly, it describes how to combine several biophysical techniques to study non-structured proteins, offering a blueprint that is likely to be relevant for a wide range of scientists.
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This content will become publicly available on August 1, 2026
Exploration of the interaction between dynein intermediate chain and dynactin p150Glued reveals a novel binding Interface
Cytoplasmic dynein is a motor protein that plays a role in a number of cellular processes including retrograde transport. In many cases, dynein needs to interact with another protein, dynactin, to be fully active. An important step in the assembly of the dynein/dynactin complex is the interaction between the N‐terminal portion of the intermediate chain (IC) subunit of dynein and the coiled‐coil 1B (CC1B) region of the p150Glued subunit of dynactin. Despite evidence for this interaction from binding studies, the exact location of where these proteins bind has remained elusive due to the dynamic nature of the interaction and the presence of intrinsically disordered regions in IC. By using intermolecular paramagnetic relaxation enhancements, we have been able to constrain the location of IC binding on p150Glued to a position that is different from what has recently been hypothesized in a model of the dynein/dynactin complex based on cryo‐electron microscopy (cryo‐EM) data and AlphaFold predictions. In addition, although phosphorylation is important for regulating dynein/dynactin interactions, we show that a phosphomimetic mutation of IC is not sufficient to alter binding with p150Glued.
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- PAR ID:
- 10627023
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Protein Science
- Volume:
- 34
- Issue:
- 8
- ISSN:
- 0961-8368
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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