LC8 dynein light chain (DYNLL1) binds to the C-terminal domain of ATM-interacting protein (ATMIN/ASCIZ) and regulates its subcellular localization

• DOI: 10.1016/j.bbrc.2011.09.093
• Publication Date: 2011-09-25T23:50:56Z
• Authors: Péter Rapali; María Flor García...; Mónica Martínez-M...; Krisztián Tárnok; Katalin Schlett; Juan Pablo Albar; Marta Bruix; László Nyitray; Ignacio Rodriguez...
• Keywords: Cytoplasmic Dyneins; 0303 health sciences; Binding Sites; Molecular Sequence Data; Dynein; Intracellular Space; Nuclear Proteins; Microtubules; Protein Structure, Tertiary; 03 medical and health sciences; Two-Hybrid System Techniques; Humans; Amino Acid Sequence; Carrier Proteins; Intracellular transport; Nuclear Magnetic Resonance, Biomolecular; ATMIN; Transcription Factors

LC8 dynein light chain (now termed DYNLL1 and DYNLL2 in mammals), a dimeric 89 amino acid protein, is a component of the dynein multi-protein complex. However a substantial amount of DYNLL1 is not associated to microtubules and it can thus interact with dozens of cellular and viral proteins that display well-defined, short linear motifs. Using DYNLL1 as bait in a yeast two-hybrid screen of a human heart library we identified ATMIN, an ATM kinase-interacting protein, as a DYNLL1-binding partner. Interestingly, ATMIN displays at least 18 SQ/TQ motifs in its sequence and DYNLL1 is known to bind to proteins with KXTQT motifs. Using pepscan and yeast two-hybrid techniques we show that DYNLL1 binds to multiple SQ/TQ motifs present in the carboxy-terminal domain of ATMIN. Recombinant expression and purification of the DYNLL1-binding region of ATMIN allowed us to obtain a polypeptide with an apparent molecular mass in gel filtration close to 400 kDa that could bind to DYNLL1 in vitro. The NMR data-driven modelled complexes of DYNLL1 with two selected ATMIN peptides revealed a similar mode of binding to that observed between DYNLL1 and other peptide targets. Remarkably, co-expression of mCherry-DYNLL1 and GFP-ATMIN mutually affected intracellular protein localization. In GFP-ATMIN expressing-cells DNA damage induced efficiently nuclear foci formation, which was partly impeded by the presence of mCherry-DYNLL1. Thus, our results imply a potential cellular interference between DYNLL1 and ATMIN functions.