Wilson Christopher G M, Kajander Tommi, Regan Lynne
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA.
FEBS J. 2005 Jan;272(1):166-79. doi: 10.1111/j.1432-1033.2004.04397.x.
There are several different families of repeat proteins. In each, a distinct structural motif is repeated in tandem to generate an elongated structure. The nonglobular, extended structures that result are particularly well suited to present a large surface area and to function as interaction domains. Many repeat proteins have been demonstrated experimentally to fold and function as independent domains. In tetratricopeptide (TPR) repeats, the repeat unit is a helix-turn-helix motif. The majority of TPR motifs occur as three to over 12 tandem repeats in different proteins. The majority of TPR structures in the Protein Data Bank are of isolated domains. Here we present the high-resolution structure of NlpI, the first structure of a complete TPR-containing protein. We show that in this instance the TPR motifs do not fold and function as an independent domain, but are fully integrated into the three-dimensional structure of a globular protein. The NlpI structure is also the first TPR structure from a prokaryote. It is of particular interest because it is a membrane-associated protein, and mutations in it alter septation and virulence.
存在几种不同的重复蛋白家族。在每个家族中，一个独特的结构基序串联重复以产生一个细长的结构。由此产生的非球状延伸结构特别适合呈现大的表面积并作为相互作用结构域发挥作用。许多重复蛋白已通过实验证明可折叠并作为独立结构域发挥功能。在四肽重复序列（TPR）中，重复单元是一个螺旋-转角-螺旋基序。大多数TPR基序以三个到超过12个串联重复的形式出现在不同的蛋白质中。蛋白质数据库中的大多数TPR结构都是孤立结构域的。在此，我们展示了NlpI的高分辨率结构，这是首个完整的含TPR蛋白的结构。我们表明，在这种情况下，TPR基序并非折叠并作为一个独立结构域发挥功能，而是完全整合到一个球状蛋白的三维结构中。NlpI结构也是来自原核生物的首个TPR结构。它特别引人关注，因为它是一种膜相关蛋白，其中的突变会改变细胞分裂和毒力。
