Crystal structure of an IclR homologue from m>Microbacteriumm> sp. strain HM58-2

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• 作者：Tomonori Akiyama ; Yusuke Yamada ; Naoki Takaya ; Shinsaku Ito ; Yasuyuki Sasaki and Shunsuke Yajima
• 关键词：isocitrate lyase regulator ; transcription factor ; Microbacterium ; hydrazide ; one-component system
• 刊名：Acta Crystallographica Section F
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：73
• 期：1
• 页码：16-23
• 全文大小：1769K
• ISSN：1744-3091

文摘

The bacterial transcription factor IclR (isocitrate lyase regulator) is a member of a one-component signal transduction system, which shares the common motif of a helix–turn–helix (HTH)-type DNA-binding domain (DBD) connected to a substrate-binding domain (SBD). Here, the crystal structure of an IclR homologue (Mi-IclR) from m>Microbacteriumm> sp. strain HM58-2, which catabolizes acylhydrazide as the sole carbon source, is reported. Mi-IclR is expected to regulate an operon responsible for acylhydrazide degradation as an initial step. Native single-wavelength anomalous diffraction (SAD) experiments were performed in combination with molecular replacement. m>CRANKm>2 from the m>CCPm>4 suite successfully phased and modelled the complete structure of a homotetramer composed of 1000 residues in an asymmetric unit, and the model was refined to 2.1 Å resolution. The overall structure of Mi-IclR shared the same domain combination as other known IclR structures, but the relative geometry between the DBD and SBD differs. Accordingly, the geometry of the Mi-IclR tetramer was unique: the putative substrate-binding site in each subunit is accessible from the outside of the tetramer, as opposed to buried inside as in the previously known IclR structures. These differences in the domain geometry may contribute to the transcriptional regulation of IclRs.