The repeat region of cortactin is intrinsically disordered in solution

• Published in: Scientific reports Vol. 7; no. 1; pp. 16696 - 10
• Main Authors: Li, Xiaofeng, Tao, Yeqing, Murphy, James W, Scherer, Alexander N, Lam, TuKiet T, Marshall, Alan G, Koleske, Anthony J, Boggon, Titus J
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 01.12.2017; Nature Publishing Group UK
• Subjects: Actin; Amino Acid Sequence; Circular Dichroism; Cortactin - chemistry; Cortactin - metabolism; Deuterium Exchange Measurement; Filaments; Hydrogen-deuterium exchange; Hydrophobicity; Ions; Light scattering; Mass Spectrometry; Mass spectroscopy; MATERIALS SCIENCE; Protein Conformation, alpha-Helical; Protein Unfolding; Scattering, Small Angle; X-Ray Diffraction; X-ray scattering
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-017-16959-1

The multi-domain protein, cortactin, contains a 37-residue repeating motif that binds to actin filaments. This cortactin repeat region comprises 6½ similar copies of the motif and binds actin filaments. To better understand this region of cortactin, and its fold, we conducted extensive biophysical analysis. Size exclusion chromatography with multi-angle light scattering (SEC-MALS) reveals that neither constructs of the cortactin repeats alone or together with the adjacent helical region homo-oligomerize. Using circular dichroism (CD) we find that in solution the cortactin repeats resemble a coil-like intrinsically disordered protein. Small-angle X-ray scattering (SAXS) also indicates that the cortactin repeats are intrinsically unfolded, and the experimentally observed radius of gyration (R ) is coincidental to that calculated by the program Flexible-Meccano for an unfolded peptide of this length. Finally, hydrogen-deuterium exchange mass spectrometry (HDX-MS) indicates that the domain contains limited hydrophobic core regions. These experiments therefore provide evidence that in solution the cortactin repeat region of cortactin is intrinsically disordered.