The gene cluster for chloramphenicol biosynthesis in Streptomyces venezuelae ISP5230 includes novel shikimate pathway homologues and a monomodular non-ribosomal peptide synthetase gene
The gene cluster for chloramphenicol biosynthesis in Streptomyces venezuelae ISP5230 includes novel shikimate pathway homologues and a monomodular non-ribosomal peptide synthetase gene
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DOI：
10.1099/00221287-147-10-2817
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发表时间：
2001-10-01
期刊：
影响因子：
2.8
通讯作者：
Vining, LC
中科院分区：
文献类型：
--
作者：
He, J;Magarvey, N;Vining, LC
委内瑞拉链霉菌ISP 5230染色体侧翼pabAB，氯霉素（Cm）生产所需的氨基-脱氧分支酸合酶基因的区域进行了检查，参与抗生素的生物合成。pabAB下游序列中的四个ORF中有三个与莽草酸途径相关的基因相似。BLASTX检索结果表明，ORF 3和ORF 4的氨基酸序列分别与分支酸脱氢酶和预苯酸脱氢酶的单功能基因编码的蛋白质相似，而ORF 3产物的序列与莽草酸途径的起始酶--脱氧阿拉伯庚酮糖酸-7-磷酸（DAHP）合酶相似。通过ORF 6产物和与Cm输出相关的膜蛋白之间的序列相似性表明与Cm生物合成的关系。BLASTX搜索GenBank中与pabAB上游染色体DNA中ORF 1翻译序列匹配的序列，未检测到与Cm生物合成相关的产物。然而，当将DNA接合转移到封闭的S.委内瑞拉突变体恢复了Cm的生产。野生型染色体的7.5 kb片段中的缺失消除了Cm的产生，证实了该区域中存在Cm生物合成基因。测序和分析发现了5个ORF，其中一个ORF（ORF）是通过GenBank的BLAST检索推导出来的，并通过比对其推导的氨基酸序列发现了其特征模体，是一个单模的非核糖体肽合成酶。基因库搜索没有确定ORF 7，但匹配的ORF 9，10和11的翻译序列与短链酮还原酶，ABC转运蛋白的ATP结合盒，辅酶A连接酶，分别。如ORF 2所示，破坏ORF 3、ORF 7、ORFS或ORF 9阻断了Cm的产生。
Regions of the Streptomyces venezuelae ISP5230 chromosome flanking pabAB, an amino-deoxychorismate synthase gene needed for chloramphenicol (Cm) production, were examined for involvement in biosynthesis of the antibiotic. Three of four ORFs in the sequence downstream of pabAB resembled genes involved in the shikimate pathway. BLASTX searches of GenBank showed that the deduced amino acid sequences of ORF3 and ORF4 were similar to proteins encoded by monofunctional genes for chorismate mutase and prephenate dehydrogenase, respectively, while the sequence of the ORFS product resembled deoxy-arabino-heptulosonate-7-phosphate (DAHP) synthase, the enzyme that initiates the shikimate pathway. A relationship to Cm biosynthesis was indicated by sequence similarities between the ORF6 product and membrane proteins associated with Cm export. BLASTX searches of GenBank for matches with the translated sequence of ORF1 in chromosomal DNA immediately upstream of pabAB did not detect products relevant to Cm biosynthesis. However, the presence of Cm biosynthesis genes in a 7.5 kb segment of the chromosome beyond ORF1 was inferred when conjugal transfer of the DNA into a blocked S. venezuelae mutant restored Cm production. Deletions in the 7.5 kb segment of the wild-type chromosome eliminated Cm production, confirming the presence of Cm biosynthesis genes in this region. Sequencing and analysis located five ORFs, one of which (ORFS) was deduced from BLAST searches of GenBank, and from characteristic motifs detected in alignments of its deduced amino acid sequence, to be a monomodular nonribosomal peptide synthetase. GenBank searches did not identify ORF7, but matched the translated sequences of ORFs 9, 10 and 11 with short-chain ketoreductases, the ATP-binding cassettes of ABC transporters, and coenzyme A ligases, respectively. As has been shown for ORF2, disrupting ORF3, ORF7, ORFS or ORF9 blocked Cm production.