Crystal structure of dimeric human ciliary neurotrophic factor determined by MAD phasing

• Published in: The EMBO journal Vol. 14; no. 12; pp. 2689 - 2699
• Main Authors: McDonald, N.Q., Panayotatos, N., Hendrickson, W.A.
• Format: Journal Article
• Language: English
• Published: England 15-06-1995
• Subjects: Amino Acid Sequence; Biological Evolution; Ciliary Neurotrophic Factor; Crystallography, X-Ray; Humans; Models, Molecular; Molecular Sequence Data; Nerve Growth Factors - chemistry; Nerve Growth Factors - genetics; Nerve Growth Factors - metabolism; Nerve Tissue Proteins - chemistry; Nerve Tissue Proteins - genetics; Nerve Tissue Proteins - metabolism; Protein Conformation; Receptor, Ciliary Neurotrophic Factor; Receptors, Nerve Growth Factor - metabolism; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Sequence Alignment
• ISSN: 0261-4189; 1460-2075
• DOI: 10.1002/j.1460-2075.1995.tb07269.x

Ciliary neurotrophic factor (CNTF) promotes the survival and differentiation of developing motor neurons and is a potential therapeutic for treating neurodegeneration and nerve injury. The crystal structure of human CNTF has been determined at 2.4 A resolution using multi‐wavelength anomalous diffraction (MAD) phasing from a single Yb3+ ions. The structure reveals that CNTF is dimeric, with a novel anti‐parallel arrangement of the subunits, not previously observed for other cytokines. Each subunit adopts a double crossover four‐helix bundle fold, in which two helices contribute to the dimer interface, whilst two different helices show pronounced kinks. Analysis of the electrostatic surface of CNTF identified residues within these kinked helices that may contact the CNTF receptor‐alpha. Solution experiments show that CNTF dimerizes at concentrations > 40 microM. Such dimers are likely to be relevant to the storage of CNTF in the peripheral nerve given the high concentrations present in this tissue. However, it is unlikely that they play a role in engaging the three distinct receptor subunits that comprise the CNTF receptor, given the low concentration of extracellular CNTF and its high potency.