Zhou Huihao, Liu Qi, Gao Yongxiang, Teng Maikun, Niu Liwen
Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.
Proteins. 2009 Sep;76(4):787-93. doi: 10.1002/prot.22465.
Transcription in archaea employs a eukaryotic-type transcription apparatus but uses bacterial-type transcription factors. NusG is one of the few archaeal transcription factors whose orthologs are essential in both bacteria and eukaryotes. Archaeal NusG is composed of only an NusG N-terminal (NGN) domain and a KOW domain, which is similar to bacterial NusG but not to the eukaryotic ortholog, Spt5. However, archaeal NusG was confirmed recently to form a complex with rpoE'' that was similar to the Spt5-Spt4 complex. Thus, archaeal NusG presents hybrid features of Spt5 and bacterial NusG. Here we report the crystal structure of NGN from the archaea Methanocaldococcus jannaschii (MjNGN). MjNGN folds to an alpha-beta-alpha sandwich without the appendant domain of bacterial NGNs, and forms a unique homodimer in crystal and solution. MjNGN alone was found to be sufficient for rpoE'' binding and an MjNGN-rpoE'' model has been constructed by rigid docking.
古菌中的转录使用真核生物类型的转录装置，但使用细菌类型的转录因子。NusG是少数几种在细菌和真核生物中其直系同源物都必不可少的古菌转录因子之一。古菌NusG仅由一个NusG N端（NGN）结构域和一个KOW结构域组成，它与细菌NusG相似，但与真核生物直系同源物Spt5不同。然而，最近证实古菌NusG与rpoE''形成了一个类似于Spt5 - Spt4复合物的复合物。因此，古菌NusG呈现出Spt5和细菌NusG的混合特征。在此我们报道了来自詹氏甲烷球菌（MjNGN）的古菌NGN的晶体结构。MjNGN折叠成一个α-β-α三明治结构，没有细菌NGN的附属结构域，并且在晶体和溶液中形成独特的同二聚体。已发现单独的MjNGN足以与rpoE''结合，并且通过刚性对接构建了MjNGN - rpoE''模型。
