Daigle François, Lerat Sylvain, Bucca Giselda, Sanssouci Édith, Smith Colin P, Malouin François, Beaulieu Carole
Centre d'Étude et de Valorisation de la Diversité Microbienne, Département de Biologie, Université de Sherbrooke, Quebec, Canada.
Department of Microbial and Cellular Sciences, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom.
J Bacteriol. 2015 Mar;197(5):913-23. doi: 10.1128/JB.02278-14. Epub 2014 Dec 22.
Although Streptomyces coelicolor is not resistant to tellurite, it possesses several TerD domain-encoding (tdd) genes of unknown function. To elucidate the function of tdd8, the transcriptomes of S. coelicolor strain M145 and of a tdd8 deletion mutant derivative (the Δtdd8 strain) were compared. Several orthologs of Mycobacterium tuberculosis genes involved in dormancy survival were upregulated in the deletion mutant at the visual onset of prodiginine production. These genes are organized in a putative redox stress response cluster comprising two large loci. A binding motif similar to the dormancy survival regulator (DosR) binding site of M. tuberculosis has been identified in the upstream sequences of most genes in these loci. A predicted role for these genes in the redox stress response is supported by the low NAD(+)/NADH ratio in the Δtdd8 strain. This S. coelicolor gene cluster was shown to be induced by hypoxia and NO stress. While the tdd8 deletion mutant (the Δtdd8 strain) was unable to maintain calcium homeostasis in a calcium-depleted medium, the addition of Ca(2+) in Δtdd8 culture medium reduced the expression of several genes of the redox stress response cluster. The results shown in this work are consistent with Tdd8 playing a significant role in calcium homeostasis and redox stress adaptation.
尽管天蓝色链霉菌对亚碲酸盐不具有抗性，但它拥有几个功能未知的编码TerD结构域的（tdd）基因。为了阐明tdd8的功能，对天蓝色链霉菌M145菌株和tdd8缺失突变体衍生物（Δtdd8菌株）的转录组进行了比较。在缺失突变体中，在视觉上开始产生灵菌红素时，几种与结核分枝杆菌休眠存活相关基因的直系同源基因上调。这些基因被组织在一个假定的氧化还原应激反应簇中，该簇包含两个大的基因座。在这些基因座中大多数基因的上游序列中已鉴定出与结核分枝杆菌的休眠存活调节因子（DosR）结合位点相似的结合基序。Δtdd8菌株中低的NAD(+)/NADH比率支持了这些基因在氧化还原应激反应中的预测作用。该天蓝色链霉菌基因簇被证明可由缺氧和NO应激诱导。虽然tdd8缺失突变体（Δtdd8菌株）在缺钙培养基中无法维持钙稳态，但在Δtdd8培养基中添加Ca(2+)可降低氧化还原应激反应簇中几个基因的表达。这项工作中所示的结果与Tdd8在钙稳态和氧化还原应激适应中发挥重要作用一致。
