Analysis and sequence of the speB gene encoding agmatine ureohydrolase, a putrescine biosynthetic enzyme in Escherichia coli
Analysis and sequence of the speB gene encoding agmatine ureohydrolase, a putrescine biosynthetic enzyme in Escherichia coli
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编码大肠杆菌中腐胺生物合成酶胍丁胺尿素水解酶的 speB 基因的分析和序列
DOI：
10.1128/jb.172.2.538-547.1990
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发表时间：
1990
影响因子：
3.2
通讯作者：
S. Boyle
中科院分区：
文献类型：
--
作者：
M. Szumanski;S. Boyle
大肠杆菌的speB基因编码胍丁胺尿素水解酶（AUH）。AUH在大肠杆菌的两条多胺生物合成途径中催化胍丁胺水解为尿素和腐胺。杆菌对E.含有speB的大肠杆菌染色体显示存在三个完整的开放阅读框（ORF），ORF 1和ORF 2在一条链上，ORF 3在另一条链上，以及一个截短的ORF，ORF 4，其终止于ORF 3上游的92个酶对。ORF 3含有speB基因的编码序列，通过互补分析证实。检测到两个ORF 3转录本：一个较短的转录本，只包括ORF 3和一个较长的转录本，包括ORF 3和ORF 4。当ORF 4序列缺失时，短转录本大量表达，但当ORF 4及其上游序列存在时，多顺反子信息占主导地位，单顺反子信息的量急剧减少。产生较短转录物的启动子在-12位含有TATACT序列，但-12位上游的序列似乎与启动子活性无关。预测的AUH的氨基酸序列包含三个区域的高度同源性的酵母，大鼠和人类的脱氢酶。
The speB gene of Escherichia coli encodes the enzyme agmatine ureohydrolase (AUH). AUH catalyzes the hydrolysis of agmatine to urea and putrescine in one of the two polyamine biosynthetic pathways in E. coli. Sequencing of a 2.97-kilobase-pair fragment of the E. coli chromosome containing speB revealed the presence of three intact open reading frames (ORFs), ORF1 and ORF2 on one strand and ORF3 on the opposite strand, as well as a truncated ORF, ORF4, which terminated 92 kilobase pairs upstream from ORF3. ORF3 contained the coding sequence of the speB gene, as confirmed by complementation analysis. Two ORF3 transcripts were detected: a shorter transcript that included only ORF3 and a longer transcript that included both ORF3 and ORF4. The short transcript was abundantly expressed when the ORF4 sequences were deleted, but when ORF4 and its upstream sequences were present, the polycistronic message predominated and the amount of the monocistronic message was drastically reduced. The promoter from which the shorter transcript was produced contained a TATACT sequence at position -12, but sequences upstream from the -12 position seemed to be irrelevant for promoter activity. The predicted amino acid sequence of AUH contained three regions of high homology to the arginases of yeasts, rats, and humans.