The intermediate chain of cytoplasmic dynein is partially disordered and gains structure upon binding to light-chain LC8

Afua Nyarko, Michael Hare, Thomas S. Hays, Elisar Barbar

Research output: Contribution to journalArticlepeer-review

59 Scopus citations

Abstract

The N-terminal domain of dynein intermediate chain, IC1-289, is highly disordered, but upon binding to dynein light-chain LC8, it undergoes a significant conformational change to a more ordered structure. Using circular dichroism and fluorescence spectroscopy, we demonstrate that the change in conformation is due to an increase in the helical structure and to enhanced compactness in the environment of tryptophan 161. An increase in helical structure and compactness is also observed with trimethylamine-N-oxide (TMAO), a naturally occurring osmolyte used here as a probe to identify regions with a propensity for induced folding. Global protection of IC1-289 from protease digestion upon LC8 binding was localized to a segment that includes residues downstream of the LC8-binding site. Several smaller constructs of IC1-289 containing the LC8-binding site and one of the predicted helix or coiled-coil segments were made. IC1-143 shows no increase in helical structure upon binding, while IC114-260 shows an increase in helical structure similar to what is observed with IC1-289. Binding of IC114-260 to LC8 was monitored by fluorescence and native gel electrophoresis and shows saturation of binding, a stoichiometry of 1:1, and moderate binding affinity. The induced folding of IC1-289 upon LC8 binding suggests that LC8 could act through the intermediate chain to facilitate dynein assembly or regulate cargo-binding interactions.

Original languageEnglish (US)
Pages (from-to)15595-15603
Number of pages9
JournalBiochemistry
Volume43
Issue number49
DOIs
StatePublished - Dec 14 2004

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