Expression of the Streptomyces coelicolor SoxR Regulon Is Intimately Linked with Actinorhodin Production
Expression of the Streptomyces coelicolor SoxR Regulon Is Intimately Linked with Actinorhodin Production
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DOI：
10.1128/jb.00916-10
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发表时间：
2010-12-01
影响因子：
3.2
通讯作者：
Chander, Monica
中科院分区：
文献类型：
--
作者：
Dela Cruz, Rica;Gao, Yang;Chander, Monica
含有[2Fe-2S]的转录因子SoxR在不同的细菌中是保守的。SOXR传统上被认为是大肠杆菌中全球氧化应激反应的调节因子，但最近的研究表明，这一功能可能仅限于肠道细菌。在绝大多数非肠道药物中，SoxR被预测为介导对内源性产生的氧化还原活性代谢物的反应。我们已经研究了SoxR调节子在天蓝色链霉菌模型中的调节和功能。与大肠杆菌soxR缺失突变体不同，天蓝色链霉菌的等价物对氧化剂不敏感，表明SoxR在后者中不增强抗氧化防御。SoxR调控天蓝色链霉菌的5个基因，包括编码一个可能的ABC转运蛋白、两个氧化还原酶、一个单加氧酶和一个可能依赖于NAD的差向异构酶/脱水酶。这些基因的表达依赖于苯偶氮喹诺酮抗生素放线菌素的产生，并且需要在SoxR中完整的[2Fe-2S]簇。这些数据表明，放线菌素，或氧化还原活性的前体，调节天蓝色链霉菌的SoxR活性，以刺激膜转运蛋白和与放线菌素剪裁酶同源的蛋白质的产生。虽然SoxR在天蓝色链霉菌中的作用仍在研究中，但这些研究支持这样的观点，即SoxR已经被适应来执行不同的生理功能，以服务于占据不同生态位和面临不同环境挑战的生物的需要。
The [2Fe-2S]-containing transcription factor SoxR is conserved in diverse bacteria. SoxR is traditionally known as the regulator of a global oxidative stress response in Escherichia coli, but recent studies suggest that this function may be restricted to enteric bacteria. In the vast majority of nonenterics, SoxR is predicted to mediate a response to endogenously produced redox-active metabolites. We have examined the regulation and function of the SoxR regulon in the model antibiotic-producing filamentous bacterium Streptomyces coelicolor. Unlike the E. coli soxR deletion mutant, the S. coelicolor equivalent is not hypersensitive to oxidants, indicating that SoxR does not potentiate antioxidant defense in the latter. SoxR regulates five genes in S. coelicolor, including those encoding a putative ABC transporter, two oxidoreductases, a monooxygenase, and a possible NAD-dependent epimerase/dehydratase. Expression of these genes depends on the production of the benzochromanequinone antibiotic actinorhodin and requires intact [2Fe-2S] clusters in SoxR. These data indicate that actinorhodin, or a redox-active precursor, modulates SoxR activity in S. coelicolor to stimulate the production of a membrane transporter and proteins with homology to actinorhodin-tailoring enzymes. While the role of SoxR in S. coelicolor remains under investigation, these studies support the notion that SoxR has been adapted to perform distinct physiological functions to serve the needs of organisms that occupy different ecological niches and face different environmental challenges.