A heterodimerizing leucine zipper coiled coil system for examining the specificity of a position interactions: Amino acids I, V, L, N, A, and K
A heterodimerizing leucine zipper coiled coil system for examining the specificity of a position interactions: Amino acids I, V, L, N, A, and K
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DOI：
10.1021/bi020486r
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发表时间：
2002-12-03
期刊：
影响因子：
2.9
通讯作者：
Vinson, C
中科院分区：
文献类型：
--
作者：
Acharya, A;Ruvinov, SB;Vinson, C
我们用异二聚亮氨酸拉链体系研究了A、V、L、1、K和N六种氨基酸螺旋间a-a‘相互作用对二聚体稳定性的贡献。圆二色谱(CD)监测了36个异源二聚体的热变性，它们产生了6个同型和30个异型a-a‘相互作用。异亮氨酸(I-I)是最稳定的同型α-a‘相互作用，每二聚体比A-A相互作用稳定9.2千卡/摩尔，比L-L和V-V相互作用稳定4.0千卡/摩尔，每二聚体比N-N相互作用稳定7.0千卡/摩尔，只有赖氨酸比丙氨酸不稳定。一个基于丙氨酸的双突变热力学循环计算了杂二聚体中a和a‘位置之间的耦合能。脂肪族氨基酸L、V和I倾向于形成同型相互作用，其耦合能为-0.6~-0.9千卡/摩尔/二聚体。但异型脂肪族相互作用具有正的耦合能，每个二聚体的耦合能为~lt；1.0千卡/摩尔。天冬酰胺的同型相互作用的耦合能为-0.5kcal/molPet，二聚体。而与脂肪族氨基酸的异型相互作用产生的耦合能在2.6-4.9千卡/摩尔/二聚体之间。同型K-K相互作用的稳定性比A-A相互作用低2.9千卡/摩尔/二聚体，但耦合能仅为0.3千卡/摩尔/二聚体。与赖氨酸、天冬酰胺或脂肪族氨基酸的异型相互作用产生相似的耦合能，范围从-0.2到-0.7千卡/摩尔/二聚体。因此，在所检测的氨基酸中，天冬酰胺对二聚专一性的贡献最大，因为在与脂肪族氨基酸的异型相互作用中有很大的正耦合能，这导致了N-N同型相互作用。
We use a heterodimerizing leucine zipper system to examine the contribution of the interhelical a-a' interaction to dimer stability for six amino acids (A, V, L, 1, K. and N). Circular dichroism (CD) spectroscopy monitored the thermal denaturation of 36 heterodimers that generate six homotypic and 30 heterotypic a-a' interactions. Isoleucine (I-I) is the most stable homotypic a-a' interaction, being 9.2 kcal/mol per dimer more stable than the A-A interaction and 4.0 kcal/mol per dimer more stable than either the L-L or V-V interaction, and 7.0 kcal/mol per dimer more stable than the N-N interaction, Only lysine was less stable than alanine. An alanine-based double-mutant thermodynamic cycle calculated coupling energies between the a and a' positions in the heterodimer. The aliphatic amino acids L, V, and I prefer to form homotypic interactions with coupling energies of -0.6 to -0.9 kcal/mol per dimer. but the heterotypic aliphatic interactions have positive coupling energies of < 1.0 kcal/mol per dimer. The asparagine homotypic interaction has a coupling energy of -0.5 kcal/mol pet, dimer. while heterotypic interactions with the aliphatic amino acids produce coupling energies ranging from 2.6 to 4.9 kcal/mol per dimer. The homotypic K-K interaction is 2.9 kcal/mol per dimer less stable than the A-A interaction, but the coupling energy is only 0.3 kcal/mol per dimer. Heterotypic interactions with lysine and either asparagine or aliphatic amino acids produce similar coupling energies ranging from -0.2 to -0.7 kcal/mol per dimer. Thus, of the amino acids that were examined, asparagine contribute, the most to dimerization specificity because of the large positive coupling energies in heterotypic interactions with the aliphatic amino acids which results in the N-N homotypic interaction.