Deciphering the role of the electrostatic interactions in the alpha-tropomyosin head-to-tail complex

Author(s)

Correa, Fernando ^[1] ; Salinas, Roberto Kopke ^[1] ; Bonvin, Alexandre M. J. J. ^[2] ; Farah, Chuck S. ^[1]

Affiliation

^[1] Univ Sao Paulo, Inst Quim, Dept Bioquim, BR-05508000 Sao Paulo - Brazil

^[2] Univ Utrecht, Bijvoet Ctr Biomol Res, Fac Sci, NL-3584 CH Utrecht - Netherlands

• Document type: Journal article
• Source: PROTEINS-STRUCTURE FUNCTION AND BIOINFORMATICS; v. 73, n. 4, p. 902-917, Dec. 2008.
• Field of knowledge: Biological Sciences - Biochemistry
• Web of Science Citations: 5

Abstract

Skeletal ALPHA-tropomyosin (Tm) is a dimeric coiled-coil protein that forms linear assemblies under low ionic strength conditions in vitro through head-to-tail interactions. A previously published NMR structure of the Tm head-to-tail complex revealed that it is formed by the insertion of the N-terminal coiled-coil of one molecule into a cleft formed by the separation of the helices at the C-terminus of a second molecule. To evaluate the contribution of charged residues to complex stability, we employed single and double-mutant Tm fragments in which specific charged residues were changed to alanine in head-to-tail binding assays, and the effects of the mutations were analyzed by thermodynamic double-mutant cycles and protein-protein docking. The results show that residues K5, K7, and D280 are essential to the stability of the complex. Though D2, K6, D275, and H276 are exposed to the solvent and do not participate in intermolecular contacts in the NMR structure, they may contribute to head-to-tail complex stability by modulating the stability of the helices at the Tm termini. (AU)

• FAPESP's process: 05/59243-3 - Structural and functional analysis of multi-prosthetic systems for the pathogenicity of Xanthomonas axonopodis pv. citri
• Grantee: Shaker Chuck Farah
• Support Opportunities: Research Projects - Thematic Grants