Ponnusamy Rajesh, Lebedev Andrey A, Pahlow Steffen, Lohkamp Bernhard
Instituto de Technologia Química e Biológica, Universidade Nova de Lisboa, Avenida da República, EAN, 2781-901 Oeiras, Portugal.
Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Didcot OX11 0FA, England.
Acta Crystallogr D Biol Crystallogr. 2014 Jun;70(Pt 6):1680-94. doi: 10.1107/S1399004714006634. Epub 2014 May 30.
Collapsin response mediator proteins (CRMPs) are cytosolic phosphoproteins that are mainly involved in neuronal cell development. In humans, the CRMP family comprises five members. Here, crystal structures of human CRMP-4 in a truncated and a full-length version are presented. The latter was determined from two types of crystals, which were either twinned or partially disordered. The crystal disorder was coupled with translational NCS in ordered domains and manifested itself with a rather sophisticated modulation of intensities. The data were demodulated using either the two-lattice treatment of lattice-translocation effects or a novel method in which demodulation was achieved by independent scaling of several groups of intensities. This iterative protocol does not rely on any particular parameterization of the modulation coefficients, but uses the current refined structure as a reference. The best results in terms of R factors and map correlation coefficients were obtained using this new method. The determined structures of CRMP-4 are similar to those of other CRMPs. Structural comparison allowed the confirmation of known residues, as well as the identification of new residues, that are important for the homo- and hetero-oligomerization of these proteins, which are critical to nerve-cell development. The structures provide further insight into the effects of medically relevant mutations of the DPYSL-3 gene encoding CRMP-4 and the putative enzymatic activities of CRMPs.
塌陷反应介导蛋白（CRMPs）是主要参与神经元细胞发育的胞质磷蛋白。在人类中，CRMP家族由五个成员组成。本文展示了截短型和全长型人类CRMP-4的晶体结构。全长型结构由两种类型的晶体确定，这两种晶体要么是孪晶，要么是部分无序的。晶体无序与有序域中的平移非晶体学对称性（NCS）相关联，并通过强度的相当复杂的调制表现出来。使用晶格平移效应的双晶格处理或一种新方法对数据进行解调，在新方法中，通过对几组强度进行独立缩放来实现解调。这种迭代协议不依赖于调制系数的任何特定参数化，而是使用当前精修的结构作为参考。使用这种新方法在R因子和图谱相关系数方面获得了最佳结果。所确定的CRMP-4结构与其他CRMPs的结构相似。结构比较证实了已知的残基，并鉴定了对这些蛋白质的同源和异源寡聚化很重要的新残基，这些寡聚化对神经细胞发育至关重要。这些结构进一步深入了解了编码CRMP-4的DPYSL-3基因的医学相关突变的影响以及CRMPs的假定酶活性。
