NssR, a member of the Crp-Fnr superfamily from Campylobacter jejuni, regulates a nitrosative stress-responsive regulon that includes both a single-domain and a truncated haemoglobin
NssR, a member of the Crp-Fnr superfamily from Campylobacter jejuni, regulates a nitrosative stress-responsive regulon that includes both a single-domain and a truncated haemoglobin
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DOI：
10.1111/j.1365-2958.2005.04723.x
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发表时间：
2005-08-01
影响因子：
3.6
通讯作者：
Park, SF
中科院分区：
文献类型：
--
作者：
Elvers, KT;Turner, SM;Park, SF
与其作为一氧化氮（NO）解毒球蛋白在空肠弯曲菌，Cgb（弯曲菌球蛋白）表达的作用是一致的强烈和特异性诱导暴露于亚硝化应激后，这表明以前未被认识到的能力，NO相关的应力传感在这种食源性病原体。在这项研究中，Fur和PerR已被排除作为cgb的主要调节因子，而Crp-Fnr超家族的成员NssR（Cj 0466）已被确定为控制该基因的亚硝化应激响应表达的主要正调节因子。因此，nssR的破坏导致诱导型cgb表达的废除，这是通过在第二个位置用其固有启动子互补插入野生型基因的染色体而恢复的。NssR缺陷型突变体比CGB突变体对NO相关应激更敏感，这种表型最有可能是由于这些细胞除了CGB外不能诱导其他NO响应组分。事实上，通过微阵列和验证性实时聚合酶链反应（PCR）在野生型和nssR突变体的全球基因表达分析，不仅证实了诱导型cgb表达对NssR的依赖性，而且还首次揭示了一种新的NssR依赖性亚硝化应激反应调节子。这种至少四个基因的调节子包括Cj 0465 c，一种截短的球蛋白。与作为Crp-Fnr超家族成员的NssR一致，在相对于结合位点中心和转录起始点的位置-40.5至-42.5的每个基因上游发现Fnr样结合序列（TTAAC-N-4-GTTAA）。定点突变证实了这个顺式作用基序介导了亚硝化胁迫诱导的cgb表达。
Consistent with its role as a nitric oxide (NO)-detoxifying globin in Campylobacter jejuni, Cgb (Campylobacter globin) expression is strongly and specifically induced following exposure to nitrosative stress, suggesting a previously unrecognized capacity for NO-related stress sensing in this food-borne pathogen. In this study, Fur and PerR have been eliminated as major regulators of cgb, and NssR (Cj0466), a member of the Crp-Fnr superfamily, has been identified as the major positive regulatory factor that controls nitrosative stress-responsive expression of this gene. Accordingly, disruption of nssR resulted in the abolition of inducible cgb expression, which was restored by a complementing chromosomal insertion of the wild-type gene with its indigenous promoter at a second location. The NssR-deficient mutant was more sensitive to NO-related stress than a cgb mutant and this phenotype most likely arises from the failure of these cells to induce other NO-responsive components in addition to Cgb. Indeed, analysis of global gene expression, by microarray and confirmatory real-time polymerase chain reaction (PCR) in the wild type and nssR mutant, not only confirmed the dependence of inducible cgb expression on NssR, but also revealed for the first time a novel NssR-dependent nitrosative stress-responsive regulon. This regulon of at least four genes includes Cj0465c, a truncated globin. Consistent with NssR being a Crp-Fnr superfamily member, an Fnr-like binding sequence (TTAAC-N-4-GTTAA) was found upstream of each gene at locations -40.5 to -42.5 relative to the centre of the binding sites and the transcription start point. Site-directed mutagenesis confirmed that this cis-acting motif mediates the nitrosative stress-inducible expression of cgb.