Delineation of the TRAK binding regions of the kinesin-1 motor proteins
FEBS LETTERS
Authors: Randall, Thomas S.; Moores, Carolyn; Stephenson, F. Anne
Abstract
Understanding specific cargo distribution in differentiated cells is a major challenge. Trafficking kinesin proteins (TRAKs) are kinesin adaptors. They bind the cargo binding domain of kinesin-1 motor proteins forming a link between the motor and their cargoes. To refine the TRAK1/2 binding sites within the kinesin-1 cargo domain, rationally designed C-terminal truncations of KIF5A and KIF5C were generated and their co-association with TRAK1/2 determined by quantitative co-immunoprecipitations following co-expression in mammalian cells. Three contributory regions forming the TRAK2 binding site within KIF5A and KIF5C cargo binding domains were delineated. Differences were found between TRAK1/2 with respect to association with KIF5A. Structured summary of protein interactions: TRAK2 physically interacts with KIF5C by anti tag coimmunoprecipitation (View interaction) TRAK1 physically interacts with KIF5A by anti tag coimmunoprecipitation (View interaction) TRAK2 physically interacts with KIF5A by anti tag coimmunoprecipitation (1, 2) (C) 2013 Federation of European Biochemical Societies. Published by Elsevier B. V. All rights reserved.
Miro proteins coordinate microtubule- and actin-dependent mitochondrial transport and distribution
EMBO JOURNAL
Authors: Lopez-Domenech, Guillermo; Covill-Cooke, Christian; Ivankovic, Davor; Halff, Els F.; Sheehan, David F.; Norkett, Rosalind; Birsa, Nicol; Kittler, Josef T.
Abstract
In the current model of mitochondrial trafficking, Miro1 and Miro2 Rho-GTPases regulate mitochondrial transport along microtubules by linking mitochondria to kinesin and dynein motors. By generating Miro1/2 double-knockout mouse embryos and single-and double-knockout embryonic fibroblasts, we demonstrate the essential and non-redundant roles of Miro proteins for embryonic development and subcellular mitochondrial distribution. Unexpectedly, the TRAK1 and TRAK2 motor protein adaptors can still localise to the outer mitochondrial membrane to drive anterograde mitochondrial motility in Miro1/2 double-knockout cells. In contrast, we show that TRAK2-mediated retrograde mitochondrial transport is Miro1-dependent. Interestingly, we find that Miro is critical for recruiting and stabilising the mitochondrial myosin Myo19 on the mitochondria for coupling mitochondria to the actin cytoskeleton. Moreover, Miro depletion during PINK1/Parkin-dependent mitophagy can also drive a loss of mitochondrial Myo19 upon mitochondrial damage. Finally, aberrant positioning of mitochondria in Miro1/2 double-knockout cells leads to disruption of correct mitochondrial segregation during mitosis. Thus, Miro proteins can fine-tune actin-and tubulin-dependent mitochondrial motility and positioning, to regulate key cellular functions such as cell proliferation.