Importance of potential interhelical salt-bridges involving interior residues for coiled-coil stability and quaternary structure.
Importance of potential interhelical salt-bridges involving interior residues for coiled-coil stability and quaternary structure.
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DOI：
10.1016/s0022-2836(02)01072-0
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发表时间：
2002-11
影响因子：
5.6
通讯作者：
D. L. McClain;D. G. Gurnon;M. G. Oakley
中科院分区：
文献类型：
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作者：
D. L. McClain;D. G. Gurnon;M. G. Oakley
卷曲螺旋由两个或多个α螺旋形成，它们以平行或反平行的相对取向排列。极性相互作用涉及残基在内部a和d的位置是重要的，用于确定的四级结构的卷曲螺旋。在异源二聚体卷曲螺旋Acid-a1-Base-a1模型中，掩埋的a-d′ Asn-Asn相互作用足以指定二聚体结构和反平行相对螺旋取向。虽然在平行卷曲螺旋中发现了等效的a-a′相互作用，但在结构特征的自然存在的反平行卷曲螺旋中没有a-d′ Asn-Asn相互作用的例子。相反，内部带电残基与相邻的e或g位置的残基形成螺旋间盐桥。使用模型卷曲螺旋异二聚体，我们已经探讨了潜在的螺旋间相互作用的作用之间的精氨酸在内部d位置和Glu在相邻的g′位置。我们的研究结果表明，这种潜在的吸引力的螺旋间库仑相互作用对螺旋取向几乎没有影响。相反，我们表明，埋葬一个单一的精氨酸残基在内部位置是足以指定一个二聚体的状态在一个显着较低的热力学成本比埋葬两个相互作用的天冬酰胺残基。
Coiled coils are formed by two or more α-helices that align in a parallel or an antiparallel relative orientation. Polar interactions involving residues at the interior a and d positions are important for determining the quaternary structure of coiled coils. In the model heterodimeric coiled-coil Acid-a1-Base-a1, a buried a–d′ Asn–Asn interaction is sufficient to specify both a dimeric structure and an antiparallel relative helix orientation. Although the equivalent a–a′ interaction is found in parallel coiled coils, there is no example of an a–d′ Asn–Asn interaction in structurally characterized, naturally occurring antiparallel coiled coils. Instead, interior charged residues form interhelical salt-bridges with residues at the adjacent e or g positions. Using a model coiled-coil heterodimer, we have explored the role of a potential interhelical interaction between an Arg at an interior d position and a Glu at the adjacent g′ position. Our results demonstrate that this potentially attractive interhelical Coulombic interaction has little or no influence on helix orientation. Instead, we show that burying a single Arg residue at an interior position is sufficient to specify a dimeric state at a significantly lower thermodynamic cost than burial of two interacting Asn residues.