Abstract
Cytoplasmic dynein is responsible for a wide range of cellular roles. How this single motor protein performs so many functions has remained a major outstanding question for many years. Part of the answer is thought to lie in the diversity of dynein regulators, but how the effects of these factors are coordinated in vivo remains unexplored. We previously found NudE to bind dynein through its light chain 8 (LC8) and intermediate chain (IC) subunits (1), the latter of which also mediates the dynein-dynactin interaction (2). We report here that NudE and dynactin bind to a common region within the IC, and compete for this site. We find LC8 to bind to a novel sequence within NudE, without detectably affecting the dynein-NudE interaction. We further find that commonly used dynein inhibitory reagents have broad effects on the interaction of dynein with its regulatory factors. Together these results reveal an unanticipated mechanism for preventing dual regulation of individual dynein molecules, and identify the IC as a nexus for regulatory interactions within the dynein complex.
Highlights
Cytoplasmic dynein performs a great variety of cellular functions using a diversity of regulators
We find the primary binding site for NudE to lie within the dynein intermediate chain (IC) N terminus, the same region implicated in dynactin binding [2, 43]
NudE Binds to the Dynein Intermediate Chain N Terminus— In a previous study we screened an array of dynein and dynactin subunits for NudE binding, and identified interactions with the dynein IC and light chain 8 (LC8) subunits [1, 15]
Summary
Cytoplasmic dynein performs a great variety of cellular functions using a diversity of regulators. Cytoplasmic dynein is a 1.2 MDa protein complex that functions as the predominant microtubule minus end-directed molecular motor in most cell types It is involved in a very wide range of cellular roles, but the underlying basis for its great functional diversity is poorly understood. The microtubule binding CAP-Gly domain of the dynactin p150Glued subunit had been assumed to contribute to the enhancement of dynein processivity, recent studies showed no effect after its removal. It was still required for complete dynactin function in vivo [6, 19, 22, 23]. The common interaction site is a target for frequently used inhibitory probes, and our results, have important implications for phenotypic analysis of dynein function in vivo
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