Structural characterization of the human Nogo-A functional domains. Solution structure of Nogo-40, a Nogo-66 receptor antagonist enhancing injured spinal cord regeneration.
The recent discovery of the Nogo family of myelin inhibitors and the Nogo-66 receptor opens up a very promising avenue for the development of therapeutic agents for treating spinal cord injury. Nogo-A, the largest member of the Nogo family, is a multidomain protein containing at least two regions responsible for inhibiting central nervous system (CNS) regeneration. So far, no structural information is available for Nogo-A or any of its structural domains. We have subcloned and expressed two Nogo-A fragments, namely the 182 residue Nogo-A(567-748) and the 66 residue Nogo-66 in Escherichia coli. CD and NMR characterization indicated that Nogo-A(567-748) was only partially structured while Nogo-66 was highly insoluble. Nogo-40, a truncated form of Nogo-66, has been previously shown to be a Nogo-66 receptor antagonist that is able to enhance CNS neuronal regeneration. Detailed NMR examinations revealed that a Nogo-40 peptide had intrinsic helix-forming propensity, even in an aqueous environment. The NMR structure of Nogo-40 was therefore determined in the presence of the helix-stabilizing solvent trifluoroethanol. The solution structure of Nogo-40 revealed two well-defined helices linked by an unstructured loop, representing the first structure of Nogo-66 receptor binding ligands. Our results provide the first structural insights into Nogo-A functional domains and may have implications in further designs of peptide mimetics that would enhance CNS neuronal regeneration.
Department of Biological Sciences, National University of Singapore, Singapore.
Minfen
M
Li
Jiahai
J
Shi
Zheng
Z
Wei
Felicia Y H
FY
Teng
Bor Luen
BL
Tang
Jianxing
J
Song
D000595:Amino Acid Sequence; D002490:Central Nervous System / Q000502:physiology; D002942:Circular Dichroism; D006131:Growth Inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D009185:Myelin Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000070798:Nogo Proteins; D019906:Nuclear Magnetic Resonance, Biomolecular; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary
D006131:Growth Inhibitors; D009185:Myelin Proteins; D000070798:Nogo Proteins; D010446:Peptide Fragments; C000603199:RTN4 protein, human