Sainsbury Sarah, Lane Laura A, Ren Jingshan, Gilbert Robert J, Saunders Nigel J, Robinson Carol V, Stuart David I, Owens Raymond J
The Oxford Protein Production Facility and Division of Structural Biology, Henry Wellcome Building for Genomic Medicine, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK.
Nucleic Acids Res. 2009 Aug;37(14):4545-58. doi: 10.1093/nar/gkp445. Epub 2009 May 27.
LysR-type transcriptional regulators (LTTRs) form the largest family of bacterial regulators acting as both auto-repressors and activators of target promoters, controlling operons involved in a wide variety of cellular processes. The LTTR, CrgA, from the human pathogen Neisseria meningitidis, is upregulated during bacterial-host cell contact. Here, we report the crystal structures of both regulatory domain and full-length CrgA, the first of a novel subclass of LTTRs that form octameric rings. Non-denaturing mass spectrometry analysis and analytical ultracentrifugation established that the octameric form of CrgA is the predominant species in solution in both the presence and absence of an oligonucleotide encompassing the CrgA-binding sequence. Furthermore, analysis of the isolated CrgA-DNA complex by mass spectrometry showed stabilization of a double octamer species upon DNA binding. Based on the observed structure and the mass spectrometry findings, a model is proposed in which a hexadecameric array of two CrgA oligomers binds to its DNA target site.
LysR 型转录调节因子（LTTRs）构成了细菌调节因子中最大的家族，它们既是自身抑制因子，又是靶启动子的激活因子，控制着参与多种细胞过程的操纵子。来自人类病原体脑膜炎奈瑟菌的 LTTR CrgA 在细菌与宿主细胞接触期间上调。在此，我们报告了调节结构域和全长 CrgA 的晶体结构，这是形成八聚体环的 LTTRs 新亚类中的首个结构。非变性质谱分析和分析超速离心表明，无论是否存在包含 CrgA 结合序列的寡核苷酸，CrgA 的八聚体形式都是溶液中的主要形式。此外，通过质谱对分离的 CrgA-DNA 复合物进行分析表明，DNA 结合后双八聚体物种得到稳定。基于观察到的结构和质谱结果，提出了一个模型，其中两个 CrgA 寡聚体的十六聚体阵列与其 DNA 靶位点结合。
