title: Stability of 100 homo and heterotypic coiled-coil a-a' pairs for ten amino acids (A, L, I, V, N, K, S, T, E, and R).
abstract: We present the thermal stability monitored by circular dichroism (CD) spectroscopy at 222 nm of 100 heterodimers that contain all possible coiled-coil a-a' pairs for 10 amino acids (I, V, L, N, A, K S, T, E, and R). This includes the stability of 36 heterodimers for 6 amino acids (I, V, L, N, A, and K) previously described and 64 new heterodimers including the 4 amino acids (S, T, E, and R). We have calculated a double mutant alanine thermodynamic cycle to determine a-a' pair coupling energies to evaluate which a-a' pairs encourage specific dimerization partners. The four new homotypic a-a' pairs (T-T, S-S, R-R, E-E) are repulsive relative to A-A and have destabilizing coupling energies. Among the 90 heterotypic a-a' pairs, the stabilizing coupling energies contain lysine or arginine paired with either an aliphatic or a polar amino acid. The range in coupling energies for each amino acid reveals its potential to regulate dimerization specificity. The a-a' pairs containing isoleucine and asparagine have the greatest range in coupling energies and thus contribute dramatically to dimerization specificity, which is to encourage homodimerization. In contrast, the a-a' pairs containing charged amino acids (K, R, and E) show the least range in coupling energies and promiscuously encourage heterodimerization.
authors.affiliation: Laboratory of Metabolism, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Asha
authors.initials: A
authors.lastname: Acharya
authors.forename: Vikas
authors.initials: V
authors.lastname: Rishi
authors.forename: Charles
authors.initials: C
authors.lastname: Vinson
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry* / Q000378:metabolism*; D002942:Circular Dichroism; D019281:Dimerization; D006801:Humans; D016350:Leucine Zippers; D009154:Mutation / Q000235:genetics; D011489:Protein Denaturation; D013816:Thermodynamics
chemical_list: D000596:Amino Acids