title: Localization of dynein light chains 1 and 2 and their pro-apoptotic ligands.
abstract: The dynein and myosin V motor complexes are multi-protein structures that function to transport molecules and organelles within the cell. DLC (dynein light-chain) proteins, found as components of both dynein and myosin V motor complexes, connect the complexes to their cargoes. One of the roles of these motor complexes is to selectively sequester the pro-apoptotic 'BH3-only' (Bcl-2 homology 3-only) proteins, Bim (Bcl-2-interacting mediator of cell death) and Bmf (Bcl-2-modifying factor), and so regulate their cell death-inducing function. In vivo DLC2 is found exclusively as a component of the myosin V motor complex and Bmf binds DLC2 selectively. On the other hand, Bim interacts with DLC1 (LC8), an integral component of the dynein motor complex. The two DLCs share 93% sequence identity yet show unambiguous in vivo specificity for their respective BH3-only ligands. To investigate this specificity the three-dimensional solution structure of DLC2 was elucidated using NMR spectroscopy. In vitro structural and mutagenesis studies show that Bmf and Bim have identical binding characteristics to recombinant DLC2 or DLC1. Thus the selectivity shown by Bmf and Bim for binding DLC1 or DLC2, respectively, does not reside in their DLC-binding domains. Remarkably, mutational analysis of DLC1 and DLC2 indicates that a single surface residue (residue 41) determines the specific localization of DLCs with their respective motor complexes. These results suggest a molecular mechanism for the specific compartmentalization of DLCs and their pro-apoptotic cargoes and implicate other protein(s) in defining the specificity between the cargoes and the DLC proteins.
authors.affiliation: Department of Biochemistry, University of Otago, Dunedin, New Zealand.
authors.forename: Catherine L
authors.initials: CL
authors.lastname: Day
authors.forename: Hamsa
authors.initials: H
authors.lastname: Puthalakath
authors.forename: Gretchen
authors.initials: G
authors.lastname: Skea
authors.forename: Andreas
authors.initials: A
authors.lastname: Strasser
authors.forename: Igor
authors.initials: I
authors.lastname: Barsukov
authors.forename: Lu-Yun
authors.initials: LY
authors.lastname: Lian
authors.forename: David C S
authors.initials: DC
authors.lastname: Huang
authors.forename: Mark G
authors.initials: MG
authors.lastname: Hinds
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000378:metabolism / Q000502:physiology; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins; D000072224:Bcl-2-Like Protein 11; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism; D002460:Cell Line; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004398:Dyneins / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D007668:Kidney / Q000166:cytology / Q000196:embryology; D008024:Ligands; D046911:Macromolecular Substances; D008565:Membrane Proteins; D051379:Mice; D008969:Molecular Sequence Data; D024701:Myosin Type V / Q000737:chemistry; D010449:Peptide Mapping; D010455:Peptides / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism*; D011518:Proto-Oncogene Proteins; D016415:Sequence Alignment
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000596:Amino Acids; D051017:Apoptosis Regulatory Proteins; C000606775:BCL2L11 protein, human; C486655:BMF protein, human; D000072224:Bcl-2-Like Protein 11; C000606776:Bcl2l11 protein, mouse; C435486:Bmf protein, mouse; D002352:Carrier Proteins; D008024:Ligands; D046911:Macromolecular Substances; D008565:Membrane Proteins; D010455:Peptides; D021122:Protein Subunits; D011518:Proto-Oncogene Proteins; D024701:Myosin Type V; D004398:Dyneins