A novel sensor of NADH/NAD+ redox poise in Streptomyces coelicolor A3(2)
A novel sensor of NADH/NAD+ redox poise in Streptomyces coelicolor A3(2)
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DOI：
10.1093/emboj/cdg453
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发表时间：
2003-09-15
期刊：
影响因子：
11.4
通讯作者：
Paget, MSB
中科院分区：
文献类型：
--
作者：
Brekasis, D;Paget, MSB
我们描述了Rex的鉴定，Rex是一种新型的氧化还原反应抑制物，似乎在革兰氏阳性细菌中广泛存在。在天蓝色链霉菌中，Rex与位于几个呼吸基因上游的操纵子(ROP)结合，包括cydABCD和rex-hemACD操纵子。Rex的DNA结合活性似乎受NADH/NAD(+)池的氧化还原平衡控制。利用电迁移率位移和表面等离子体共振分析，我们发现NADH而不是NAD(+)抑制了Rex的DNA结合活性。然而，NAD(+)与NADH竞争Rex结合，使Rex能够在一定范围的NAD(H)浓度范围内感知氧化还原平衡。REX被预测包括一个吡啶核苷酸结合域(Rossmann折叠)，可能起关键结构和核苷酸结合作用的残基是高度保守的。为了支持这一点，签名基序(GlyXGlyXXGly)中的中心甘氨酸被证明是氧化还原传感所必需的。REX同源物存在于大多数革兰氏阳性细菌中，包括人类病原体，如金黄色葡萄球菌、单核细胞增生性李斯特菌和肺炎链球菌。
We describe the identification of Rex, a novel redox-sensing repressor that appears to be widespread among Gram-positive bacteria. In Streptomyces coelicolor Rex binds to operator (ROP) sites located upstream of several respiratory genes, including the cydABCD and rex-hemACD operons. The DNA-binding activity of Rex appears to be controlled by the redox poise of the NADH/NAD(+) pool. Using electromobility shift and surface plasmon resonance assays we show that NADH, but not NAD(+), inhibits the DNA-binding activity of Rex. However, NAD(+) competes with NADH for Rex binding, allowing Rex to sense redox poise over a range of NAD(H) concentrations. Rex is predicted to include a pyridine nucleotide-binding domain (Rossmann fold), and residues that might play key structural and nucleotide binding roles are highly conserved. In support of this, the central glycine in the signature motif (GlyXGlyXXGly) is shown to be essential for redox sensing. Rex homologues exist in most Gram-positive bacteria, including human pathogens such as Staphylococcus aureus, Listeria monocytogenes and Streptococcus pneumoniae.