We report the crystal structure and bioinformatic analysis of SF173, a functionally uncharacterized protein from the human enteropathogenic bacteria Shigella flexneri. The structure shows a tightly interlinked dimer formed by adimeric core comprising α2 and α3 helices from both subunits and swapping the N-terminal α1 helix of each monomer. Structural inspection and genomic analysis results suggest that the SF173 might play its putative function by binding to SF172, the partially overlapped upstream product in the operon. As YaeO (an SF172 orthologue) has been identified to be an inhibitor of the bacterial transcription terminator Rho protein, SF173 is suggested to be involved in the regulation of Rho-dependent transcription termination, by inhibiting the Rho protein binding to SF172/YaeO.

中文翻译：

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弗氏志贺氏菌SF173的晶体结构揭示了一个二聚体螺旋束构象。

我们报告SF173的晶体结构和生物信息学分析，SF173是一种来自人类肠道致病菌弗氏志贺氏菌的功能性未表征的蛋白质。该结构显示出紧密连接的二聚体，其由包括来自两个亚基的α2和α3螺旋的二聚体核心形成，并且交换每个单体的N端α1螺旋。结构检查和基因组分析结果表明，SF173可能通过与操纵子中部分重叠的上游产物SF172结合而发挥其推定功能。由于已确认YaeO（SF172直系同源物）是细菌转录终止子Rho蛋白的抑制剂，因此建议SF173通过抑制Rho蛋白与SF172 / YaeO的结合来参与Rho依赖性转录终止的调控。