TY - JOUR
T1 - Repurposing Triphenylmethane Dyes to Bind to Trimers Derived from Aβ
AU - Salveson, Patrick J.
AU - Haerianardakani, Sepehr
AU - Thuy-Boun, Alexander
AU - Yoo, Stan
AU - Kreutzer, Adam G.
AU - Demeler, Borries
AU - Nowick, James S.
N1 - Funding Information:
This work was supported by the National Institutes of Health GM097562 and the National Science Foundation CHE- 1507840 and CHE-1808096. The authors thank the Laser Spectroscopy Facility at University of California, Irvine for assistance with fluorescence measurements. The development of UltraScan was supported by NIH grant GM120600 and NSF grant NSF-ACI-1339649. Supercomputer calculations were performed on Comet at the San Diego Supercomputing Center, supported through NSF/XSEDE grant TGMCB070039N, and on Lonestar-5 at the Texas Advanced Computing Center, supported through UT grant TG457201. We also acknowledge the support of the San Antonio Cancer Institute grant P30 CA054174 for support of the Center for Analytical Ultracentrifugation of Macromolecular Assemblies at the University of Texas Health Science Center at San Antonio. P.J.S. thanks the UCI Training Program in Chemical and Structural Biology T32 GM108561 for training grant support as well as ARCS Foundation Orange County for additional support.
Publisher Copyright:
© 2018 American Chemical Society.
PY - 2018/9/19
Y1 - 2018/9/19
N2 - Soluble oligomers of the β-amyloid peptide, Aβ, are associated with the progression of Alzheimer's disease. Although many small molecules bind to these assemblies, the details of how these molecules interact with Aβ oligomers remain unknown. This paper reports that crystal violet, and other C3 symmetric triphenylmethane dyes, bind to C3 symmetric trimers derived from Aβ17-36. Binding changes the color of the dyes from purple to blue, and causes them to fluoresce red when irradiated with green light. Job plot and analytical ultracentrifugation experiments reveal that two trimers complex with one dye molecule. Studies with several triphenylmethane dyes reveal that three N,N-dialkylamino substituents are required for complexation. Several mutant trimers, in which Phe19, Phe20, and Ile31 were mutated to cyclohexylalanine, valine, and cyclohexylglycine, were prepared to probe the triphenylmethane dye binding site. Size exclusion chromatography, SDS-PAGE, and X-ray crystallographic studies demonstrate that these mutations do not impact the structure or assembly of the triangular trimer. Fluorescence spectroscopy and analytical ultracentrifugation experiments reveal that the dye packs against an aromatic surface formed by the Phe20 side chains and is clasped by the Ile31 side chains. Docking and molecular modeling provide a working model of the complex in which the triphenylmethane dye is sandwiched between two triangular trimers. Collectively, these findings demonstrate that the X-ray crystallographic structures of triangular trimers derived from Aβ can be used to guide the discovery of ligands that bind to soluble oligomers derived from Aβ.
AB - Soluble oligomers of the β-amyloid peptide, Aβ, are associated with the progression of Alzheimer's disease. Although many small molecules bind to these assemblies, the details of how these molecules interact with Aβ oligomers remain unknown. This paper reports that crystal violet, and other C3 symmetric triphenylmethane dyes, bind to C3 symmetric trimers derived from Aβ17-36. Binding changes the color of the dyes from purple to blue, and causes them to fluoresce red when irradiated with green light. Job plot and analytical ultracentrifugation experiments reveal that two trimers complex with one dye molecule. Studies with several triphenylmethane dyes reveal that three N,N-dialkylamino substituents are required for complexation. Several mutant trimers, in which Phe19, Phe20, and Ile31 were mutated to cyclohexylalanine, valine, and cyclohexylglycine, were prepared to probe the triphenylmethane dye binding site. Size exclusion chromatography, SDS-PAGE, and X-ray crystallographic studies demonstrate that these mutations do not impact the structure or assembly of the triangular trimer. Fluorescence spectroscopy and analytical ultracentrifugation experiments reveal that the dye packs against an aromatic surface formed by the Phe20 side chains and is clasped by the Ile31 side chains. Docking and molecular modeling provide a working model of the complex in which the triphenylmethane dye is sandwiched between two triangular trimers. Collectively, these findings demonstrate that the X-ray crystallographic structures of triangular trimers derived from Aβ can be used to guide the discovery of ligands that bind to soluble oligomers derived from Aβ.
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U2 - 10.1021/jacs.8b06568
DO - 10.1021/jacs.8b06568
M3 - Article
C2 - 30125493
AN - SCOPUS:85053266340
VL - 140
SP - 11745
EP - 11754
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 37
ER -