Hfq Is Required for Optimal Nitrate Assimilation in the Cyanobacterium Anabaena sp. Strain PCC 7120
Hfq Is Required for Optimal Nitrate Assimilation in the Cyanobacterium Anabaena sp. Strain PCC 7120
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Hfq 是蓝藻鱼腥藻中最佳硝酸盐同化所必需的。
DOI：
10.1128/jb.00254-11
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发表时间：
2011
影响因子：
3.2
通讯作者：
A. Vioque
中科院分区：
文献类型：
--
作者：
Elena Puerta;A. Vioque
Hfq是一种RNA结合蛋白，参与细菌基因表达的转录后调控。它通过与调节性小RNA（sRNA）结合而起作用，这赋予了调节的特异性。最近，在蓝藻基因组中注释了Hfq蛋白的直向同源物，尽管其通过与sRNA相互作用来调节基因表达的能力尚未得到证实。鱼腥藻菌株PCC 7120是一种丝状蓝细菌，在缺乏结合氮的情况下，能够通过分化称为异形胞的特化细胞来固定大气氮。我们已经产生了鱼腥藻PCC 7120的hfq敲除突变体。该基因的缺失导致在硝酸盐存在下异形胞的分化，表明硝酸盐同化的缺陷。我们发现hfq突变细胞在硝酸盐和亚硝酸盐的运输和利用方面受到影响。对nir操纵子中编码硝酸盐同化途径不同元件的几个基因表达的分析表明，它们在突变细胞中的转录下调。我们还观察到，基因ntcB和cnaT，参与调节的nir操纵子，显示出较低的表达在细胞缺乏Hfq。最后，当hfq重新引入突变体中时，在硝酸盐存在下不再观察到异形胞分化。因此，我们的研究结果表明，RNA分子伴侣Hfq参与调节的nir操纵子，虽然这种调节的机制仍然是未知的。
ABSTRACT Hfq is an RNA binding protein involved in posttranscriptional regulation of gene expression in bacteria. It acts by binding to regulatory small RNAs (sRNAs), which confer specificity for the regulation. Recently, orthologues of the Hfq protein were annotated in cyanobacterial genomes, although its capacity to regulate gene expression by interacting with sRNAs has not been yet demonstrated. Anabaena sp. strain PCC 7120 is a filamentous cyanobacterium that, in the absence of combined nitrogen, is able to fix atmospheric nitrogen by differentiating specialized cells called heterocysts. We have generated an hfq knockout mutant of Anabaena sp. PCC 7120. Deletion of this gene results in differentiation of heterocysts in the presence of nitrate, suggesting a defect in nitrate assimilation. We show that hfq mutant cells are affected in transport and use of nitrate and nitrite. An analysis of the expression of several genes in the nir operon, encoding different elements of the nitrate assimilation pathway, demonstrates a downregulation of their transcription in mutant cells. We also observed that genes ntcB and cnaT, involved in the regulation of the nir operon, show a lower expression in cells lacking Hfq. Finally, when hfq was reintroduced in the mutant, heterocyst differentiation was no longer observed in the presence of nitrate. Therefore, our results indicate that the RNA chaperone Hfq is involved in the regulation of the nir operon, although the mechanism for this regulation is still unknown.
影响因子：
16
作者：
Zhang, AX;Wassarman, KM;Storz, G
通讯作者：
Storz, G
影响因子：
4.5
作者：
Soper, Toby J.;Woodson, Sarah A.
通讯作者：
Woodson, Sarah A.