Evidence that the Myxococcus xanthus frz genes are developmentally regulated.
Evidence that the Myxococcus xanthus frz genes are developmentally regulated.
复制标题
有证据表明，黄色粘球菌 frz 基因受到发育调控。
DOI：
10.1128/jb.171.11.6174-6186.1989
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发表时间：
1989
影响因子：
3.2
通讯作者：
Zusman,DR
中科院分区：
文献类型：
--
作者：
Weinberg,RA;Zusman,DR
黄色粘球菌的卷曲（frz）突变体不能形成子实体。这些菌株不是形成离散的土丘，而是聚集成具有圆形和缠结外观的细丝。导致这种表型的突变已被定位到五个互补组，frzA，frzB，frzCD，frzE和frzF。所有已被发现参与控制的定向运动的细菌，除了frzB，是同源的肠道细菌的趋化基因。在这份报告中，我们提出了一个研究的前四个基因的frz基因簇（frzA，frzB，frzCD，和frzE）的表达的调节，通过使用Tn 5-乳糖转录融合基因表达的报告。我们发现，这些frz基因的发育调控，与他们的转录高峰期的时间约早期丘形成（12至18小时）。通过酶联免疫吸附测定法分析FrzCD表达，显示在15小时的发展超过营养细胞表达水平的10倍更大的诱导。北方杂交分析表明frz基因以操纵子的形式排列。为了检验这一假设，构建了双突变体，其在报告基因Tn 5-lac的上游或下游含有Tn 5 -132。双突变体中frz基因的表达与前四个基因（frzA、frzB、frzCD和frzE）被组织为具有内部启动子的操纵子的假设一致。frzCD中的插入突变降低了基因表达，无论它们是在报告基因Tn 5-lac的上游还是下游，这表明FrzCD蛋白从frzA上游的启动子调节整个操纵子的转录。证据表明，FrzE是所需的诱导转录以及。当frz突变被放置在不能聚集的菌株中时（标签），frz基因在结果琼脂上以升高的水平表达;这种高水平的表达保持了几天。这些结果表明标签基因产物与frz功能相互作用。
The frizzy (frz) mutants of Myxococcus xanthus are unable to form fruiting bodies. Instead of forming discrete mounds, these strains aggregate as filaments which have a circular and tangled appearance. Mutations leading to this phenotype have been mapped to five complementation groups, frzA, frzB, frzCD, frzE, and frzF. All have been found to be involved in the control of directional movement of the bacteria and, except for frzB, to be homologous to the chemotaxis genes of enteric bacteria. In this report we present a study of the regulation of expression of the first four genes of the frz gene cluster (frzA, frzB, frzCD, and frzE) by using Tn5-lac transcriptional fusions as reporters of gene expression. We found that these frz genes are developmentally regulated, with their transcription peaking at about the time of early mound formation (12 to 18 h). Analysis of FrzCD expression by enzyme-linked immunosorbent assay showed a 10-fold greater induction at 15 h of development over the level of vegetative cell expression. Northern blot hybridization analysis suggested that the frz genes were arranged as an operon. To test this hypothesis, double mutants were constructed which contained Tn5-132 either upstream or downstream of the reporter Tn5-lac. The expression of the frz genes in the double mutants was consistent with the hypothesis that the first four genes (frzA, frzB, frzCD, and frzE) are organized as an operon with an internal promoter. Insertion mutations in frzCD lowered gene expression whether they were upstream or downstream of the reporter Tn5-lac, suggesting that the FrzCD protein regulates transcription of the entire operon from a promoter upstream of frzA. Evidence is presented suggesting that FrzE is required for induction of transcription as well. When frz mutations were placed in strains that were unable to aggregate (tag), the frz genes were expressed at an elevated level on fruiting agar; this high level of expression was maintained for several days. These results suggest that the tag gene products interact with the frz functions.