3s96

Publication Abstract from PubMed

Abnormal polyglutamine (polyQ) tracts are the only common feature in nine proteins that each cause a dominant neurodegenerative disorder. In Huntington's disease, tracts longer than 36 glutamines in the protein huntingtin (htt) cause degeneration. In situ, monoclonal antibody 3B5H10 binds to different htt fragments in neurons in proportion to their toxicity. Here, we determined the structure of 3B5H10 Fab to 1.9 A resolution by X-ray crystallography. Modeling demonstrates that the paratope forms a groove suitable for binding two beta-rich polyQ strands. Using small-angle X-ray scattering, we confirmed that the polyQ epitope recognized by 3B5H10 is a compact two-stranded hairpin within monomeric htt and is abundant in htt fragments unbound to antibody. Thus, disease-associated polyQ stretches preferentially adopt compact conformations. Since 3B5H10 binding predicts degeneration, this compact polyQ structure may be neurotoxic.

Disease-Associated Polyglutamine Stretches in Monomeric Huntingtin Adopt a Compact Structure.,Peters-Libeu C, Miller J, Rutenber E, Newhouse Y, Krishnan P, Cheung K, Hatters D, Brooks E, Widjaja K, Tran T, Mitra S, Arrasate M, Mosquera LA, Taylor D, Weisgraber KH, Finkbeiner S J Mol Biol. 2012 Jan 28. PMID:22306738^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.