Variation in expression of the Haemophilus influenzae HMW adhesins:: A prokaryotic system reminiscent of eukaryotes
Variation in expression of the Haemophilus influenzae HMW adhesins:: A prokaryotic system reminiscent of eukaryotes
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DOI：
10.1073/pnas.96.3.1077
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发表时间：
1999-02-02
影响因子：
11.1
通讯作者：
St Geme, JW
中科院分区：
文献类型：
--
作者：
Dawid, S;Barenkamp, SJ;St Geme, JW
许多真核基因的表达受到位于特定基因 5' 非翻译区内的长串串联重复序列的调节。在这项研究中，我们描述了流感嗜血杆菌的调节系统，其与真核生物中发现的调节系统惊人相似。我们发现，HMW1 和 HMW2 粘附素的表达根据 hmw1A 和 hmw2A 启动子中 7-bp 串联重复的数量而变化。重复序列位于两个独立的转录起始位点之间，并发挥抑制作用，因此重复序列数量的增加会导致特定 mRNA 和蛋白质产生水平逐步下降，反之亦然。 HMW1和HMW2的表达范围在非常弱和非常强之间变化，其间有一系列等级。 hmw1A 和 hmw2A 启动子重复次数的变化发生在体外传代、感染动物模型以及人类自然感染过程中的各个菌落中。这种调节系统在原核生物中是独特的，并且可能通过增加适应潜力来增强生物体的致病性。
Expression of a number of eukaryotic genes is regulated by long stretches of tandem repeats located within the 5' untranslated region of the particular gene. In this study, we describe a regulatory system in Haemophilus influenzae with striking similarities to those found in eukaryotes. We show that expression of the HMW1 and HMW2 adhesins varies based on the number of 7-bp tandem repeats in the hmw1A and hmw2A promoters. The repeats lie between two separate transcription initiation sites and exert a repressive effect, such that increases in repeat number result in step-wise decreases in levels of specific mRNA and protein production and vice versa. The range of expression of HMW1 and HMW2 varies between very weak and very strong, with a series of gradations in between. Variation in the number of repeats in the hmw1A and hmw2A promoters occurs in individual colonies passaged in vitro, in an animal model of infection, and during natural infection in humans. This system of regulation is unique in prokaryotes and likely enhances the pathogenicity of the organism by increasing adaptive potential.