DciA is a newly discovered bacterial protein involved in loading the replicative helicase DnaB onto DNA at the initiation step of chromosome replication. Its three-dimensional structure is composed of a folded N-terminal domain (residues 1–111) resembling K Homology domains and a long disordered C-terminal tail (residues 112–157) which structure–activity relationship remains to be elucidated. In the present study on Vibrio cholerae DciA, we emphasize the importance of its disordered region to load DnaB onto DNA using surface plasmon resonance (SPR) and isothermal titration microcalorimetry (ITC). Then we characterize the conformational ensemble of the full-length protein using a combination of circular dichroism (CD), small angle X-ray scattering (SAXS), and molecular dynamics (MD) simulations. The atomic-level structural ensemble generated by MD simulations is in very good agreement with SAXS data. From initial conformations of the C-terminal tail without any secondary structure, our simulations bring to light several transient helical structures in this segment, which might be molecular recognition features (MoRFs) for the binding to DnaB and its recruitment and loading onto DNA.

DciA 是一种新发现的细菌蛋白质，它在染色体复制的起始步骤将复制解旋酶 DnaB 加载到 DNA 上。其三维结构由类似于 K 同源结构域的折叠 N 端结构域（残基 1-111）和长无序的 C 端尾部（残基 112-157）组成，其结构-活性关系仍有待阐明。在目前关于霍乱弧菌的研究中DciA，我们强调其无序区域使用表面等离子体共振 (SPR) 和等温滴定微量热法 (ITC) 将 DnaB 加载到 DNA 上的重要性。然后，我们结合使用圆二色性 (CD)、小角 X 射线散射 (SAXS) 和分子动力学 (MD) 模拟来表征全长蛋白质的构象集合。MD 模拟生成的原子级结构系综与 SAXS 数据非常吻合。从没有任何二级结构的 C 末端尾部的初始构象来看，我们的模拟揭示了该段中的几个瞬时螺旋结构，这可能是与 DnaB 结合及其募集和加载到 DNA 上的分子识别特征 (MoRF)。