Casares S, Sadqi M, López-Mayorga O, Martínez J C, Conejero-Lara F
Departamento de Química Física e Instituto de Biotecnología, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain.
FEBS Lett. 2003 Mar 27;539(1-3):125-30. doi: 10.1016/s0014-5793(03)00212-6.
We have studied the effects produced by site-directed mutagenesis upon energetic and structural cooperativity in the Src homology region 3 domain of alpha-spectrin. The mutation of Asn47 to Gly or Ala in the distal loop brings about significant changes to the global stability of the domain in spite of not affecting its structure to any great extent. The binding affinity for a proline-rich peptide is also largely diminished in both mutant domains. We have compared the apparent Gibbs energies of the amide hydrogen-deuterium exchange (HX) between the wild-type and the Gly47 mutant. The observed changes in the Gibbs energy of HX indicate a remarkable energetic cooperativity in this small domain. Regions of the domain's core have a high cooperativity with the position of the mutation, indicating that their HX occurs mainly in states in which the distal loop is unstructured. More flexible regions, which undergo HX mainly by local motions, show a lower but still considerable cooperativity with the distal loop. We conclude that there is an important correlation between regional stability and cooperativity in this small domain.
我们研究了定点诱变对α-血影蛋白Src同源区3结构域的能量和结构协同性所产生的影响。尽管对结构影响不大，但远端环中Asn47突变为Gly或Ala会给该结构域的整体稳定性带来显著变化。在两个突变结构域中，对富含脯氨酸肽的结合亲和力也大幅降低。我们比较了野生型和Gly47突变体之间酰胺氢-氘交换（HX）的表观吉布斯自由能。HX吉布斯自由能的观测变化表明，在这个小结构域中存在显著的能量协同性。该结构域核心区域与突变位置具有高度协同性，表明它们的HX主要发生在远端环无结构的状态下。主要通过局部运动进行HX的更灵活区域，与远端环的协同性较低，但仍相当可观。我们得出结论，在这个小结构域中，区域稳定性和协同性之间存在重要关联。
