Ankyrin recognizes both surface character and shape of the 14–15 di-repeat of β-spectrin

• Published in: Biochemical and biophysical research communications 2010-02, Vol.392 (4), p.490-494
• Main Authors: La-Borde, Penelope J., Stabach, Paul R., Simonović, Ivana, Morrow, Jon S., Simonović, Miljan
• Format: Article
• Language: English
• Subjects: Ankyrin; Ankyrins - chemistry; Ankyrins - genetics; Ankyrins - metabolism; Erythrocyte membrane; Isothermal titration calorimetry; Mutation; Protein Conformation; Repetitive Sequences, Nucleic Acid; Spectrin; Spectrin - chemistry; Spectrin - genetics; Spectrin - metabolism
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2010.01.046

The spectrin-based cytoskeleton is critical for cell stability, membrane organization and membrane protein trafficking. At its core is the high-affinity complex between β-spectrin and ankyrin. Defects in either of these proteins may cause hemolytic disease, developmental disorders, neurologic disease, and cancer. Crystal structures of the minimal recognition motifs of ankyrin and β-spectrin have been determined and distinct recognition mechanisms proposed. One focused on the complementary surface charges of the minimal recognition motifs, whereas the other identified an unusual kink between β-spectrin repeats and suggested a conformation-sensitive binding surface. Using isothermal titration calorimetry and site-directed mutagenesis, we demonstrate the primacy of the inter-repeat kink as the critical determinant underlying spectrin’s ankyrin affinity. The clinical implications of this are discussed in light of recognized linker mutations and polymorphisms in the β-spectrins.