Reciprocal transcriptional and posttranscriptional growth-phase-dependent expression of sfh, a gene that encodes a paralogue of the nucleoid-associated protein H-NS
Reciprocal transcriptional and posttranscriptional growth-phase-dependent expression of sfh, a gene that encodes a paralogue of the nucleoid-associated protein H-NS
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DOI：
10.1128/jb.00685-06
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发表时间：
2006-11-01
影响因子：
3.2
通讯作者：
Dorman, Charles J.
中科院分区：
文献类型：
--
作者：
Doyle, Marie;Dorman, Charles J.
福氏志贺氏菌2457T株的IncHI1自传质粒PSF-R27含有sfh基因，该基因编码的蛋白质与全球转录调控因子和类核相关蛋白H-NS及其类似物StpA具有很强的氨基酸序列同源性。此前，我们发现SFH mRNA的表达是生长阶段相关的，因此在37℃的Lennox肉汤中生长的培养物中，在指数生长的早期阶段很容易检测到转录本，但在静止期开始时检测不到。相反，当SFH mRNA丰富时，SFH蛋白在早期指数生长期表达很低，而当SFH转录表达较低时，它在稳定期早期高水平表达(P.Deighan，C.Beloin和C.J.Dorman，Mol)。微生物。48：1401-1416,2003)。这种反常的mRNA和蛋白质表达模式并不是由于对mRNA或蛋白质稳定性的生长阶段依赖效应，也不是由于已知的SFH、StpA和H-NS蛋白影响SFH基因表达的能力。相反，我们的数据表明，在早期的指数增长中，SFH mRNA的翻译受到了阻止，随着培养进入生长的稳定阶段，这种抑制作用得到了缓解。用异源序列替换SFH mRNA的5‘末端和翻译起始信号并没有改变SFH蛋白的生长阶段依赖性表达，这表明翻译的生长阶段控制是该信息的另一个组成部分所固有的。
The IncHI1 self-transmissible plasmid pSf-R27 from Shigella flexneri 2a strain 2457T harbors sfh, a gene that codes for a protein with strong amino acid sequence homology to the global transcription regulator and nucleoid-associated protein H-NS and to its paralogue, StpA. Previously, we discovered that the expression of sfh mRNA is growth phase dependent such that in cultures growing in Lennox broth at 37 degrees C, the transcript is readily detectable in the early stages of exponential growth but is not detectable at the onset of stationary phase. In contrast, the Sfh protein is poorly expressed in early-exponential growth when sfh mRNA is abundant whereas it is expressed to a high level in early stationary phase, when sfh transcript expression is low (P. Deighan, C. Beloin, and C. J. Dorman, Mol. Microbiol. 48:1401-1416,2003). This unusual pattern of reciprocal mRNA and protein expression is not due to growth phase-dependent effects on either mRNA or protein stability, nor is it due to the known abilities of the Sfh, StpA, and H-NS proteins to influence sfh gene expression. Instead, our data point to a blockade of sfh mRNA translation in early-exponential growth that is relieved as the culture enters the stationary phase of growth. Replacing the 5' end and translation initiation signals of the sfh mRNA with heterologous sequences did not alter the growth phase-dependent expression of the Sfh protein, suggesting that growth phase control of translation is intrinsic to another component of the message.