Spectrin self-association site: characterization and study of beta-spectrin mutations associated with hereditary elliptocytosis.

Abstract

Most of hereditary elliptocytosis (HE) cases are related to a spectrin dimer (SpD) self-association defect. The severity of haemolysis is correlated with the extent of the SpD self-association defect, which itself depends on the location of the mutation regarding the tetramerization site. This site is presumed to involve the first C helix of the alpha chain and the last two helices, A and B, of the beta chain to reconstitute a triple helical structure (A, B and C), as observed along spectrin. Using recombinant peptides, we demonstrated that the first C helix of the alpha chain and the last two helices of the beta chain alone are not sufficient to establish interactions, which only occurred when a complete triple-helical repeat was added to each partner. One adjacent repeat is necessary to stabilize the conformation of both N- and C-terminal structures directly involved in the interaction site and is sufficient to generate a binding affinity similar to that observed in the native molecule. Producing peptides carrying a betaHE mutation, we reproduced the tetramerization defect as observed in patients. Therefore, the betaW2024R and betaW2061R mutations, which replace the invariant tryptophan and a residue located in the hydrophobic core, respectively, affect alpha-beta interactions considerably. In contrast, the betaA2013V mutation, which modifies a residue located outside any presumed interacting regions, has a minor effect on the interaction.

• Authors: G Nicolas, S Pedroni, C Fournier, H Gautero, C Craescu, D Dhermy, M C Lecomte
• Journal: The Biochemical journal (Biochem J) Vol. 332 ( Pt 1) Pg. 81-9 (May 15 1998) ISSN: 0264-6021 [Print] England
• PMID: 9576854 (Publication Type: Journal Article)

Chemical References

• Peptide Fragments
• Recombinant Proteins
• Spectrin

Topics

• Binding Sites (genetics)
• Circular Dichroism
• Dimerization
• Elliptocytosis, Hereditary (genetics)
• Erythrocytes (chemistry)
• Humans
• Mutagenesis, Site-Directed (genetics)
• Mutation (genetics)
• Peptide Fragments (metabolism)
• Protein Binding (genetics)
• Protein Structure, Secondary
• Recombinant Proteins (metabolism)
• Spectrin (genetics, metabolism)