Details

Autor(en) / Beteiligte

• Zelenay, Viviane
• Arzt, Michael E
• Bibow, Stefan
• Schwab, Martin E
• Riek, Roland

Titel

The Neurite Outgrowth Inhibitory Nogo-A- delta 20 Region Is an Intrinsically Disordered Segment Harbouring Three Stretches with Helical Propensity

Ist Teil von

• PloS one, 2016-09, Vol.11 (9)

Erscheinungsjahr

2016

Quelle

EZB-FREE-00999 freely available EZB journals

Beschreibungen/Notizen

• Functional recovery from central neurotrauma, such as spinal cord injury, is limited by myelin-associated inhibitory proteins. The most prominent example, Nogo-A, imposes an inhibitory cue for nerve fibre growth via two independent domains: Nogo-A- delta 20 (residues 544-725 of the rat Nogo-A sequence) and Nogo-66 (residues 1026-1091). Inhibitory signalling from these domains causes a collapse of the neuronal growth cone via individual receptor complexes, centred around sphingosine 1-phosphate receptor 2 (S1PR2) for Nogo-A- delta 20 and Nogo receptor 1 (NgR1) for Nogo-66. Whereas the helical conformation of Nogo-66 has been studied extensively, only little structural information is available for the Nogo-A- delta 20 region. We used nuclear magnetic resonance (NMR) spectroscopy to assess potential residual structural propensities of the intrinsically disordered Nogo-A- delta 20. Using triple resonance experiments, we were able to assign 94% of the non-proline backbone residues. While secondary structure analysis and relaxation measurements highlighted the intrinsically disordered character of Nogo-A- delta 20, three stretches comprising residues 561EAIQESL567, 639EAMNVALKALGT650, and 693SNYSEIAK700 form transient alpha -helical structures. Interestingly, 561EAIQESL567 is situated directly adjacent to one of the most conserved regions of Nogo-A- delta 20 that contains a binding motif for [Beta]1-integrin. Likewise, 639EAMNVALKALGT650 partially overlaps with the epitope recognized by 11C7, a Nogo-A-neutralizing antibody that promotes functional recovery from spinal cord injury. Diffusion measurements by pulse-field gradient NMR spectroscopy suggest concentration- and oxidation state-dependent dimerisation of Nogo-A- delta 20. Surprisingly, NMR and isothermal titration calorimetry (ITC) data could not validate previously shown binding of extracellular loops of S1PR2 to Nogo-A- delta 20.