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High-affinity heterotetramer formation between the large myelin-associated glycoprotein and the dynein light chain DYNLL1

DOI: 10.1111/jnc.14598 DOI Help

Authors: Matti Myllykoski (University of Oulu) , Maria A. Eichel (Max Planck Institute of Experimental Medicine; University of Göttingen) , Ramona B. Jung (Max Planck Institute of Experimental Medicine) , Sørge Kelm (University of Bremen) , Hauke B. Werner (Max Planck Institute of Experimental Medicine) , Petri Kursula (University of Oulu; University of Bergen)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of Neurochemistry

State: Published (Approved)
Published: September 2018

Abstract: The close association of myelinated axons and their myelin sheaths involves numerous intercellular molecular interactions. For example, myelin‐associated glycoprotein (MAG) mediates myelin‐to‐axon adhesion and signalling via molecules on the axonal surface. However, knowledge about intracellular binding partners of myelin proteins, including MAG, has remained limited. The two splice isoforms of MAG, S‐ and L‐MAG, display distinct cytoplasmic domains and spatiotemporal expression profiles. We used yeast 2‐hybrid screening to identify interaction partners of L‐MAG and found the dynein light chain DYNLL1 (also termed DLC8). DYNLL1 homodimers are known to facilitate dimerization of target proteins. L‐MAG and DYNLL1 associate with high affinity, as confirmed with recombinant proteins in vitro. Structural analyses of the purified complex indicate that the DYNLL1‐binding segment is localized close to the L‐MAG C terminus, next to the Fyn kinase Tyr phosphorylation site. The crystal structure of the complex between DYNLL1 and its binding segment on L‐MAG shows 2:2 binding in a parallel arrangement, indicating a heterotetrameric complex. The homology between L‐MAG and previously characterized DYNLL1‐ligands is limited, and some details of binding‐site interactions are unique for L‐MAG. The structure of the complex between the entire L‐MAG cytoplasmic domain and DYNLL1, as well as that of the the extracellular domain of MAG, were modeled based on small‐angle X‐ray scattering data, allowing structural insights into L‐MAG interactions on both membrane surfaces. Our data imply that DYNLL1 dimerizes L‐MAG, but not S‐MAG, through the formation of a specific 2:2 heterotetramer. This arrangement is likely to affect, in an isoform‐specific manner, the functions of MAG in adhesion and myelin‐to‐axon signalling.

Journal Keywords: myelin; L‐MAG; protein structure; DYNLL1/DLC8; intrinsically disordered protein; heterotetramer; axon‐glia interaction

Subject Areas: Chemistry, Biology and Bio-materials

Instruments: B21-High Throughput SAXS

Other Facilities: ESRF; BESSY; EMBL/DESY

Added On: 08/10/2018 09:18

Discipline Tags:

Biochemistry Neurology Chemistry Structural biology Life Sciences & Biotech

Technical Tags:

Scattering Small Angle X-ray Scattering (SAXS)