Small RNA ArrF Regulates the Expression of sodB and feSII Genes in Azotobacter vinelandii
Small RNA ArrF Regulates the Expression of sodB and feSII Genes in Azotobacter vinelandii
复制标题
DOI：
10.1007/s00284-008-9248-z
复制
发表时间：
2008-12-01
影响因子：
2.6
通讯作者：
Kwon, Young-Man
中科院分区：
文献类型：
--
作者：
Jung, Yean-Sung;Kwon, Young-Man
维氏固氮菌在染色体的非编码区含有类似 prrF 的序列。与铜绿假单胞菌 PrrF 小 RNA 编码基因一样，本文命名为 arrF（涉及 Fe 的固氮菌调节 RNA）的序列的表达在野生型细胞中响应铁耗竭而增加了 100 倍。在铁充足的毛皮突变体中，ArrF 的水平也增加到相同程度，但当该毛皮突变体与野生型毛皮基因互补时，ArrF 的水平回落至野生型水平。这些结果，加上 arrF 基因位于非编码区，表明该基因编码铁响应性小 RNA，其表达受到 Fur-Fe2+ 复合物的负调控。破坏该 arrF 基因会上调含铁超氧化物歧化酶和 FeSII 蛋白的表达，而毛皮突变或铁耗竭会降低其转录物水平。假设ArrF通过反义RNA机制抑制Fur控制下的基因的表达，则预测每个转录本的5'非翻译区中的一个短区域与ArrF的核心序列非常互补。然而，与铜绿假单胞菌 PrrF 在三羧酸循环和乙醛酸循环中具有广泛靶点不同，ArrF 对这些基因几乎没有影响。 ArrF 和 PrrF 靶标之间的重叠性较差，并且仅存在于固氮细菌物种染色体中的 FeSII 基因受 ArrF 控制，这一发现表明 ArrF 可能具有独特的靶标，其中一些靶标参与 N-2 固定。
Azotobacter vinelandii contains a prrF-like sequence in a noncoding region of the chromosome. Like the Pseudomonas aeruginosa PrrF small RNA-encoding genes, the expression of the sequence, herein named arrF (Azotobacter regulatory RNA involving Fe), was increased 100-fold in wild-type cells in response to iron depletion. The level of ArrF was also increased to the same degree in the iron-replete fur mutant, but down back to a wild-type level when this fur mutant was complemented with the wild-type fur gene. These results, with the location of arrF gene in a noncoding region, suggest that this gene encodes an iron-responsive small RNA whose expression is negatively regulated by the Fur-Fe2+ complex. Disruption of this arrF gene upregulated the expression of iron-containing superoxide dismutase and FeSII protein, whereas fur mutation or iron depletion decreased the level of their transcript. A short region in the 5'-untranslated region of each transcript was predicted to be quite complementary to the core sequence of ArrF, assuming that ArrF represses the expression of the genes under Fur control by an antisense RNA mechanism. However, unlike the P. aeruginosa PrrF that has extensive targets in the tricarboxylic acid cycle and glyoxylate cycle, ArrF had little effect on those genes. The findings that there is a poor overlap between ArrF and PrrF targets and that the FeSII gene, which is present only in the chromosome of nitrogen-fixing bacterial species, is controlled by ArrF suggest that ArrF might have unique targets, some of which are involved in N-2 fixation.