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Self‐assembly of β‐turn motif‐connected tandem repeats of Aβ 16‐22 and its aromatic analogs
Author(s) -
Datta Debika,
Harikrishna Adicherla,
Nagaraj Ramakrishnan,
Chaudhary Nitin
Publication year - 2019
Publication title -
peptide science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.533
H-Index - 7
ISSN - 2475-8817
DOI - 10.1002/pep2.24099
Subject(s) - thioflavin , peptide , chemistry , turn (biochemistry) , fibril , dipeptide , tandem repeat , structural motif , fluorescence , biophysics , amyloid (mycology) , peptide sequence , self assembly , amyloid fibril , stereochemistry , biochemistry , amyloid β , biology , alzheimer's disease , medicine , inorganic chemistry , physics , disease , pathology , quantum mechanics , genome , gene , organic chemistry
Self‐assembly of peptides and proteins into aggregates with a signature of cross‐β conformation is a hallmark of amyloids. Short peptides have provided important insights in understanding the various interactions that drive self‐assembly as well as the molecular architecture of the self‐assembled structures. The short amyloidogenic‐stretch of β‐amyloid, Aβ 16‐22 (Ac‐KLVFFAE‐am), is a good model peptide to study the aspects of β‐amyloid fibril formation. In order to investigate how a turn‐supporting sequence could modulate the interaction of the Ac‐KLV XZ AE‐am chains, where X and Z are the aromatic amino acids, Phe, Tyr, or Trp, we investigated the self‐assembly of Ac‐KLVFFAE‐am, Ac‐KLVFYAE‐am, Ac‐KLVYYAE‐am, and Ac‐KLVWWAE‐am separated by turn‐inducing dipeptide motifs, Asn‐Gly, D Pro‐Gly, and Aib‐ D Pro. The peptides harboring β‐turn‐inducing motifs aggregate rapidly causing large enhancements in thioflavin T (ThT) fluorescence compared to control, β‐turn motif lacking peptides. The morphology of fibrils strongly depends on the type of β‐turn. Ac‐KLVFYAE‐am repeats separated by Aib‐ D Pro and D Pro‐Gly have the highest aggregation propensity among all the peptides studied; they caused very large enhancement in ThT fluorescence. Ac‐KLVYYAE‐am is largely non‐amyloidogenic; the D Pro‐Gly and Aib‐ D Pro connected repeats, however, resulted in distinct fibrils that bind ThT. The study indicates that β‐turn motifs can be exploited to modulate and control the aggregation propensity of peptides and the morphology of aggregates.