title: Structure of Tctex-1 and its interaction with cytoplasmic dynein intermediate chain.
abstract: The minus-ended microtubule motor cytoplasmic dynein contains a number of low molecular weight light chains including the 14-kDa Tctex-1. The assembly of Tctex-1 in the dynein complex and its function are largely unknown. Using partially deuterated, (15)N,(13)C-labeled protein samples and transverse relaxation-optimized NMR spectroscopic techniques, the secondary structure and overall topology of Tctex-1 were determined based on the backbone nuclear Overhauser effect pattern and the chemical shift values of the protein. The data showed that Tctex-1 adopts a structure remarkably similar to that of the 8-kDa light chain of the motor complex (DLC8), although the two light chains share no amino acid sequence homology. We further demonstrated that Tctex-1 binds directly to the intermediate chain (DIC) of dynein. The Tctex-1 binding site on DIC was mapped to a 19-residue fragment immediately following the second alternative splicing site of DIC. Titration of Tctex-1 with a peptide derived from DIC, which contains a consensus sequence R/KR/KXXR/K found in various Tctex-1 target proteins, indicated that Tctex-1 binds to its targets in a manner similar to that of DLC8. The experimental results presented in this study suggest that Tctex-1 is likely to be a specific cargo adaptor for the dynein motor complex.
authors.affiliation: Department of Biochemistry, the Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, People's Republic of China.
authors.forename: Y K
authors.initials: YK
authors.lastname: Mok
authors.forename: K W
authors.initials: KW
authors.lastname: Lo
authors.forename: M
authors.initials: M
authors.lastname: Zhang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D003593:Cytoplasm / Q000737:chemistry*; D018076:DNA, Complementary / Q000378:metabolism; D004398:Dyneins / Q000737:chemistry* / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005982:Glutathione Transferase / Q000378:metabolism; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D008868:Microtubule Proteins / Q000737:chemistry*; D008869:Microtubule-Associated Proteins; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D056427:t-Complex Genome Region
chemical_list: D018076:DNA, Complementary; C533386:Dynlt1b protein, mouse; D008868:Microtubule Proteins; D008869:Microtubule-Associated Proteins; D009687:Nuclear Proteins; D011994:Recombinant Proteins; D005982:Glutathione Transferase; D004398:Dyneins