Role of Integration Host Factor in the Transcriptional Activation of Flagellar Gene Expression in Caulobacter crescentus
Role of Integration Host Factor in the Transcriptional Activation of Flagellar Gene Expression in Caulobacter crescentus
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整合宿主因子在新月柄杆菌鞭毛基因表达转录激活中的作用
作者：
Rachel E. Muir;J. Gober
在新月茎杆菌（Caulobacter crescent）分裂前细胞中，编码鞭毛胞质外成分的III类和IV类鞭毛基因在新生的簇生室中转录。这种不对称的表达模式归因于σ54依赖性转录激活子FlbD的区隔活性。此外，这些暂时转录的鞭毛启动子具有dna结合蛋白整合宿主因子（IHF）的一致序列，位于上游FlbD结合位点和启动子序列之间。在此，我们删除了编码IHF β亚基ihfB （himD）的C. crescentus基因，并检测了对鞭毛基因表达的影响。ΔihfB菌株表现出轻微的细胞形态缺陷和运动性受损。使用鞭毛启动子报告融合，我们观察到III类鞭毛启动子亚群的表达水平因IHF缺失而降低。然而，其中一个启动子fliK-lacZ在没有IHF的情况下表现出野生型细胞周期调节的表达模式。因此，IHF对于一些晚期鞭毛基因的最大转录是必需的。结果发现ΔihfB菌株表达的IV类鞭毛蛋白FljL数量显著减少，这是转录活性降低的结果。我们的研究结果表明，ΔihfB菌株表现出的运动性缺陷很可能是由于它无法积累iv类编码的27 kda鞭毛蛋白亚基FljL。
ABSTRACT In the Caulobacter crescentus predivisional cell, class III and IV flagellar genes, encoding the extracytoplasmic components of the flagellum, are transcribed in the nascent swarmer compartment. This asymmetric expression pattern is attributable to the compartmentalized activity of the σ54-dependent transcriptional activator FlbD. Additionally, these temporally transcribed flagellar promoters possess a consensus sequence for the DNA-binding protein integration host factor (IHF), located between the upstream FlbD binding site and the promoter sequences. Here, we deleted the C. crescentus gene encoding the β-subunit of the IHF, ihfB (himD), and examined the effect on flagellar gene expression. The ΔihfB strain exhibited a mild defect in cell morphology and impaired motility. Using flagellar promoter reporter fusions, we observed that expression levels of a subset of class III flagellar promoters were decreased by the loss of IHF. However, one of these promoters, fliK-lacZ, exhibited a wild-type cell cycle-regulated pattern of expression in the absence of IHF. Thus, IHF is required for maximal transcription of several late flagellar genes. The ΔihfB strain was found to express significantly reduced amounts of the class IV flagellin, FljL, as a consequence of reduced transcriptional activity. Our results indicate that the motility defect exhibited by the ΔihfB strain is most likely attributable to its failure to accumulate the class IV-encoded 27-kDa flagellin subunit, FljL.
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鉴定参与柄杆菌鞭毛基因定时控制的顺式和反式元件。
影响因子：
5.6
作者：
Gober,JW;Xu,H;Dingwall,AK;Shapiro,L
通讯作者：
Shapiro,L
影响因子：
2.7
作者：
Michael E. Kovach;R. Phillips;P. Elzer;R. Roop;K. Peterson
通讯作者：
Michael E. Kovach;R. Phillips;P. Elzer;R. Roop;K. Peterson
新月柄杆菌中一组正向调节的鞭毛基因启动子，与肺炎克雷伯菌的 nif 基因启动子具有序列同源性。
影响因子：
5.6
作者：
Mullin,D;Minnich,S;Chen,LS;Newton,A
通讯作者：
Newton,A
DOI：
10.1073/pnas.86.17.6656
发表时间：
1989
影响因子：
11.1
作者：
Xu,H;Dingwall,A;Shapiro,L
通讯作者：
Shapiro,L
新月柄杆菌鞭毛蛋白基因转录的启动子图谱和细胞周期调控。
DOI：
10.1073/pnas.84.5.1142
发表时间：
1987
影响因子：
11.1
作者：
Minnich,SA;Newton,A
通讯作者：
Newton,A