Identification of the omega4406 regulatory region, a developmental promoter of Myxococcus xanthus, and a DNA segment responsible for chromosomal position-dependent inhibition of gene expression.
Identification of the omega4406 regulatory region, a developmental promoter of Myxococcus xanthus, and a DNA segment responsible for chromosomal position-dependent inhibition of gene expression.
复制标题
鉴定 omega4406 调控区、黄色粘球菌的发育启动子以及负责染色体位置依赖性基因表达抑制的 DNA 片段。
DOI：
10.1128/jb.187.12.4149-4162.2005
复制
发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Kroos,Lee
中科院分区：
文献类型：
--
作者：
Loconto,Jennifer;Viswanathan,Poorna;Nowak,ScottJ;Gloudemans,Monica;Kroos,Lee
当饥饿时，黄色粘球菌细胞相互发送信号，协调它们的运动，基因表达和分化。C-信号需要细胞与细胞接触，并且由聚集体中的细胞排列带来的接触增加被认为增加C-信号，其诱导许多基因的表达，导致杆状细胞分化成球形孢子。C-信号转导涉及到thecsgA基因的产物。AcsgAmutant不能表达许多基因，这些基因通常在发育过程中约6小时后被诱导。通过在M.黄色染色体Tn 5将flacZ的转录定位于Ω4406启动子上游。在这项研究中，Ω4406启动子区域通过分析mRNA和测试不同上游DNA片段驱动M中发育相关基因表达的能力来鉴定。xanthusΩ4406 mRNA的5′端位于Tn 5插入位点上游约1.3kb处。当与acZ融合并整合在M.黄染色体的Tn 5 lacΩ4406的发育表达模式与Tn 5 lacΩ4406相似。假定的转录起始位点的上游的DNA序列是惊人的相似，其他C-信号依赖基因的启动子区域。在acsgA突变体中，来自1.0 kb片段的发育性acZ表达被消除，但在与提供C信号的野生型细胞共同发育时，该表达被恢复，这表明Ω4406启动子响应细胞外C信号。有趣的是，紧邻Tn 5 lacΩ4406上游的0.8 kb DNA片段抑制了整合在染色体中噬菌体附着位点而不是正常Ω4406位置的转录融合体中下游lacZ报告基因的表达。据我们所知，这是M中的第一个例子。黄变性是一种染色体位置依赖性的基因表达效应，可归因于启动子区域外的DNA片段。
When starved,Myxococcus xanthuscells send signals to each other that coordinate their movements, gene expression, and differentiation. C-signaling requires cell-cell contact, and increasing contact brought about by cell alignment in aggregates is thought to increase C-signaling, which induces expression of many genes, causing rod-shaped cells to differentiate into spherical spores. C-signaling involves the product of thecsgAgene. AcsgAmutant fails to express many genes that are normally induced after about 6 h into the developmental process. One such gene was identified by insertion of Tn5 lacat site Ω4406 in theM. xanthuschromosome. Tn5 lacfused transcription oflacZto the upstream Ω4406 promoter. In this study, the Ω4406 promoter region was identified by analyzing mRNA and by testing different upstream DNA segments for the ability to drive developmentallacZexpression inM. xanthus. The 5′ end of Ω4406 mRNA mapped to approximately 1.3 kb upstream of the Tn5 lacinsertion. A 1.0-kb DNA segment from 0.8 to 1.8 kb upstream of the Tn5 lacinsertion, when fused tolacZand integrated at a phage attachment site in theM. xanthuschromosome, showed a similar pattern of developmental expression as Tn5 lacΩ4406. The DNA sequence upstream of the putative transcriptional start site was strikingly similar to promoter regions of other C-signal-dependent genes. DevelopmentallacZexpression from the 1.0-kb segment was abolished in acsgAmutant but was restored upon codevelopment of thecsgAmutant with wild-type cells, which supply C-signal, demonstrating that the Ω4406 promoter responds to extracellular C-signaling. Interestingly, the 0.8-kb DNA segment immediately upstream of Tn5 lacΩ4406 inhibited expression of a downstreamlacZreporter in transcriptional fusions integrated at a phage attachment site in the chromosome but not at the normal Ω4406 location. To our knowledge, this is the first example inM. xanthusof a chromosomal position-dependent effect on gene expression attributable to a DNA segment outside the promoter region.