Identification of the Omega4514 regulatory region, a developmental promoter of Myxococcus xanthus that is transcribed in vitro by the major vegetative RNA polymerase.
Identification of the Omega4514 regulatory region, a developmental promoter of Myxococcus xanthus that is transcribed in vitro by the major vegetative RNA polymerase.
复制标题
鉴定 Omega4514 调控区，它是黄色粘球菌的发育启动子，由主要植物 RNA 聚合酶在体外转录。
DOI：
10.1128/jb.184.12.3348-3359.2002
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发表时间：
2002
影响因子：
3.2
通讯作者：
Kroos,Lee
中科院分区：
文献类型：
--
作者：
Hao,Tong;Biran,Dvora;Velicer,GregoryJ;Kroos,Lee
Ω4514是黄粘球菌基因组中Tn5 lac插入位点，该位点将lacz表达融合到发育调节启动子中。插入位点上游的DNA被克隆，启动子被定位。启动子在序列上与植物启动子相似，而σARNA聚合酶是生长m的主要RNA聚合酶。黄原，从这个启动子开始体外转录。在启动子下游和Ω4514插入之前确定了两个完整的开放阅读框。第一个基因产物（ORF1）具有假定的螺旋-转-螺旋dna结合基序，并显示序列与转录调控因子相似。ORF2与谷氨酸辅酶A （CoA）转移酶的亚基A最为相似，参与谷氨酸发酵。Tn5 lacΩ4514插入ORF3的第三个密码子，与谷氨酰胺辅酶a转移酶的B亚基相似。orf1断裂突变体表现出轻微的孢子缺陷，而forf2的断裂和Ω4514 inf3的插入都没有引起缺陷。根据DNA序列分析，这三个基因可能与第四个基因共转录，其产物类似于酒精脱氢酶。ORF1在发育过程中延迟和减少操纵子的表达，但这种负性自动调节的解除并不能完全解释操纵子的调节，因为在anorf1突变体的发育过程中，一个含有启动子的小片段的表达被强烈诱导。此外，多个上游DNA元件是完整发育表达所必需的。这些结果表明，转录激活也调节操纵子。Ω4514是发育调节m的第一个例子。它的调控似乎涉及ORF1的负向自我调控和一种或多种转录激活因子的正向调控。
Ω4514 is the site of a Tn5 lacinsertion in theMyxococcus xanthusgenome that fuseslacZexpression to a developmentally regulated promoter. DNA upstream of the insertion site was cloned, and the promoter was localized. The promoter resembles vegetative promoters in sequence, and σARNA polymerase, the major form of RNA polymerase in growingM. xanthus, initiated transcription from this promoter in vitro. Two complete open reading frames were identified downstream of the promoter and before the Ω4514 insertion. The first gene product (ORF1) has a putative helix-turn-helix DNA-binding motif and shows sequence similarity to transcriptional regulators. ORF2 is most similar to subunit A of glutaconate coenzyme A (CoA) transferase, which is involved in glutamate fermentation. Tn5 lacΩ4514 is inserted in the third codon of ORF3, which is similar to subunit B of glutaconate CoA-transferase. Anorf1disruption mutant exhibited a mild sporulation defect, whereas neither a disruption oforf2nor insertion Ω4514 inorf3caused a defect. Based on DNA sequence analysis, the three genes are likely to be cotranscribed with a fourth gene whose product is similar to alcohol dehydrogenases. ORF1 delays and reduces expression of the operon during development, but relief from this negative autoregulation does not fully explain the regulation of the operon, because expression from a small promoter-containing fragment is strongly induced during development of anorf1mutant. Also, multiple upstream DNA elements are necessary for full developmental expression. These results suggest that transcriptional activation also regulates the operon. Ω4514 is the first example of a developmentally regulatedM. xanthusoperon that is transcribed by the major vegetative RNA polymerase, and its regulation appears to involve both negative autoregulation by ORF1 and positive regulation by one or more transcriptional activators.