A Bacteriophage Capsid Protein Provides a General Amyloid Interaction Motif (GAIM) That Binds and Remodels Misfolded Protein Assemblies

作者：Krishnan Rajaraman^*; Tsubery Haim; Proschitsky Ming Y; Asp Eva; Lulu Michal; Gilead Sharon; Gartner Myra; Waltho Jonathan P; Davis Peter J; Hounslow Andrea M; Kirschner Daniel A; Inouye Hideyo; Myszka David G; Wright Jason; Solomon Beka; Fisher Richard A

来源：Journal of Molecular Biology, 2014, 426(13): 2500-2519.

DOI：10.1016/j.jmb.2014.04.015

• amyloid
• amyloid remodeling
• gene 3 protein
• Ig fusion

Misfolded protein aggregates, characterized by a canonical amyloid fold, play a central role in the pathobiology of neurodegenerative diseases. Agents that bind and sequester neurotoxic intermediates of amyloid assembly, inhibit the assembly or promote the destabilization of such protein aggregates are in clinical testing. Here, we show that the gene 3 protein (g3p) of filamentous bacteriophage mediates potent generic binding to the amyloid fold. We have characterized the amyloid binding and conformational remodeling activities using an array of techniques, including X-ray fiber diffraction and NMR. The mechanism for g3p binding with amyloid appears to reflect its physiological role during infection of Escherichia colt, which is dependent on temperature-sensitive interdomain unfolding and cis-trans prolyl isomerization of g3p. In addition, a natural receptor for g3p, ToIA-C, competitively interferes with A beta binding to g3p. NMR studies show that g3p binding to A beta fibers is predominantly through middle and C-terminal residues of the A beta subunit, indicating beta strand-g3p interactions. A recombinant bivalent g3p molecule, an immunoglobulin Fc (Ig) fusion of the two N-terminal g3p domains, (1) potently binds A beta fibers (fA beta) (K-D = 9.4 nM); (2); blocks fA beta assembly (IC50 similar to 50 nM) and (3) dissociates fA beta 13 (EC50 = 40-100 nM). The binding of g3p to misfolded protein assemblies is generic, and amyloid-targeted activities can be demonstrated using other misfolded protein systems. Taken together, our studies show that g3p(N1N2) acts as a general amyloid interaction motif.

• 出版日期2014-6-26