3GLW: Quaternary Structure Of Drosophila Melanogaster IcTCTEX-1LC8; Allosteric Interactions Of Dynein Light Chains With Dynein Intermediate Chain

Citation:
Abstract
Dynein light chains are thought to increase binding efficiency of dynein intermediate chain to both dynein heavy chain and dynactin, but their exact role is not clear. Isothermal titration calorimetry and x-ray crystallography reported herein indicate that multivalency effects underlie efficient dynein assembly and regulation. For a ternary complex of a 60-amino acid segment of dynein intermediate chain (IC) bound to two homodimeric dynein light chains Tctex1 and LC8, there is a 50-fold affinity enhancement for the second light chain binding. For a designed IC construct containing two LC8 sites, observed the 1000-fold enhancement reflects a remarkably pure entropic chelate effect of a magnitude commensurate with theoretical predictions. The lower enhancement in wild-type IC is attributed to unfavorable free energy changes associated with incremental interactions of IC with Tctex1. Our results show assembled dynein IC as an elongated, flexible polybivalent duplex, and suggest that polybivalency is an important general mechanism for constructing stable yet reversible and functionally versatile complexes.
PDB ID: 3GLWDownload
MMDB ID: 76716
PDB Deposition Date: 2009/3/12
Updated in MMDB: 2009/12
Experimental Method:
x-ray diffraction
Resolution: 3.15  Å
Source Organism:
synthetic construct
Similar Structures:
Biological Unit for 3GLW: octameric; determined by author
Molecular Components in 3GLW
Label Count Molecule
Proteins (8 molecules)
4
Dynein Light Chain 1, Cytoplasmic(Gene symbol: ctp)
Molecule annotation
4
Dynein Intermediate Chain
Molecule annotation
* Click molecule labels to explore molecular sequence information.

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