Zinc uptake regulator (Zur) is a transcriptional regulator that represses zinc acquisition genes under high zinc conditions. The aim of this study was to identify and investigate the role of Zur-binding motifs (Zur boxes) in the differential regulation of Zur target genes, including the zinT, znuA, znuCB-zur operon, the troCBA operon, and yciC, in Agrobacterium tumefaciens. DNase I footprinting and gel shift assays were performed, confirming that Zur directly binds to 18-bp inverted repeat motifs found in the promoter of these Zur-regulated genes. Furthermore, promoter-lacZ fusions and mutagenesis of the identified Zur boxes were performed to assess the role of each Zur box. A Zur box found in the zinT promoter was required for zinc-dependent repression by Zur. The intergenic region between the znuA gene and the znuCB-zur operon contains two Zur boxes, named A and C, which immediately precede the genes znuA and znuC, respectively. Zur box A, but not Zur box C, was essential for the repression of the znuA promoter. Both Zur boxes A and C were implicated in the repression of the znuC promoter, in which mutation of either box alone was sufficient for full derepression of the znuC promoter. Three Zur boxes named T, M, and Y were identified in the intergenic region between the troCBA operon and the yciC gene. Zur box Y, which immediately precedes yciC, was shown to be responsible for Zur repression of the yciC promoter. In contrast, two Zur boxes, T and M, were essential for the complete repression of the troCBA operon, and full derepression of the troC promoter was exhibited when both Zur boxes were mutated simultaneously. Sequence analysis of the identified Zur boxes revealed a correlation between deviation from the core recognition sequence of the Zur box and the requirement of two Zur boxes for Zur regulation of distinctive promoters.

中文翻译：

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Zur盒的鉴定及其在根癌农杆菌C58中Zur regulon的差异调控中的作用的确定。

锌摄取调节剂（Zur）是在高锌条件下抑制锌获取基因的转录调节剂。本研究的目的是鉴定和研究Zur结合基序（Zur盒）在农杆菌中Zur靶基因（包括zinT，znuA，znuCB-zur操纵子，troCBA操纵子和yciC）的差异调控中的作用。根瘤菌。进行了DNase I足迹和凝胶迁移分析，证实Zur直接结合在这些Zur调控基因的启动子中发现的18 bp反向重复基序。此外，进行启动子-lacZ融合和已鉴定Zur盒的诱变，以评估每个Zur盒的作用。在ZinT启动子中发现的Zur盒对于Zur依赖锌的抑制作用是必需的。znuA基因和znuCB-zur操纵子之间的基因间隔区域包含两个Zur框，分别命名为A和C，分别位于基因znuA和znuC之前。Zur盒A，但不是Zur盒C，对于znuA启动子的阻遏是必不可少的。Zur box A和Cur都与znuC启动子的抑制有关，其中单独一个box的突变足以完全解除znuC启动子的抑制。在troCBA操纵子与yciC基因之间的基因间区域中，发现了三个名为T，M和Y的Zur盒。已显示紧接yciC的Zur盒Y负责yciC启动子的Zur抑制。相比之下，两个Zur盒（T和M）对于troCBA操纵子的完全抑制是必不可少的，当两个Zur盒同时突变时，troC启动子被完全抑制。鉴定出的Zur盒的序列分析揭示了与Zur盒的核心识别序列的偏离与两个Zur盒对独特启动子的Zur调节的需求之间的相关性。