Gene structure, organization, expression, and potential regulatory mechanisms of arginine catabolism in Enterococcus faecalis
Gene structure, organization, expression, and potential regulatory mechanisms of arginine catabolism in Enterococcus faecalis
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DOI：
10.1128/jb.184.22.6289-6300.2002
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发表时间：
2002-11-01
影响因子：
3.2
通讯作者：
Rubio, V
中科院分区：
文献类型：
--
作者：
Barcelona-Andrés, B;Marina, A;Rubio, V
尽管粪肠球菌是发酵精氨酸分解代谢的精氨酸脱亚胺酶 (ADI) 途径生化研究的范例，但该生物体中该途径的遗传信息很少。我们通过在从粪肠球菌 lambdagt11 基因组文库克隆的 8,228 bp 区域中表征一个形成转录单元（由粪肠球菌中的 Northern 印迹和引物延伸揭示）的五基因簇（与 ADI 操纵子相对应）来填补这一重要空白。还鉴定出了相对 DNA 链中的另外 4 个基因和同一 DNA 链中的 1 个基因。对蛋白质产物的研究，包括异源表达和/或序列比较，使我们能够确定或提出 10 个基因中除 I 之外的所有基因的功能。 ADI 操纵子基因 arcABCRD 分别编码 ADI、鸟氨酸转氨甲酰酶、氨基甲酸酯激酶、推定的 Crp/Fnr 型调节因子 (ArcR) 和推定的鸟氨酸-精氨酸逆向转运蛋白 (ArcD)。精氨酸诱导 arcABCRD 的表达，最有可能是通过两个基因 argR1 和 argR2 编码的两个同源 ArgR/AhrC 型调节因子，这两个基因位于每条 DNA 链中的 arcABCRD 之前，并且单顺反子转录，它们的转录受到葡萄糖和精氨酸的不同影响。在 arcA 和 argR1/argR2 本身的启动子区域中发现了潜在的 ArgR1/ArgR2（双和单）结合序列。此外，在 argR1/argR2 和 arcA 启动子区域中分别发现了 ArcR 和 CcpA 的推定结合序列。在确定的其他三个基因中，两个形成转录单位并编码假定的金属敏感转录调节因子（ArsR）和半胱氨酸蛋白酶。
Although Enteroccus faecalis is the paradigm for biochemical studies on the arginine deiminase (ADI) pathway of fermentative arginine catabolism, little genetic information exists on this pathway in this organism. We fill this important gap by characterizing, in an 8,228-bp region cloned from a lambdagt11 genomic library of E. faecalis, a five-gene cluster forming a transcriptional unit (revealed by Northern blots and primer extension in E. faecalis) that corresponds to the ADI operon. Four additional genes in the opposite DNA strand and one in the same DNA strand are also identified. Studies on the protein products, including heterologous expression and/or sequence comparisons, allow us to ascertain or propose functions for all but I of the 10 genes. The ADI operon genes, arcABCRD, encode, respectively, ADI, ornithine transcarbamylase, carbamate kinase, a putative Crp/Fnr-type regulator (ArcR), and a putative ornithine-arginine antiporter (ArcD). Arginine induces the expression of arcABCRD, most likely by means of two homologous ArgR/AhrC-type regulators encoded by two genes, argR1 and argR2, that precede arcABCRD in each DNA strand and that are transcribed monocistronically, their transcription being influenced differentially by glucose and arginine. Potential ArgR1/ArgR2 (double and single) binding sequences are found in the promoter regions of arcA and of argR1/argR2 themselves. In addition, putative binding sequences for ArcR and for CcpA are found, respectively, in the argR1/argR2 and arcA promoter regions. Of the three other genes identified, two form a transcriptional unit and encode a putative metal-sensitive transcriptional regulator (ArsR) and a cysteine protease.