Sharma Vijay K, Casey Thomas A
Food Safety and Enteric Pathogens Research Unit, United States Department of Agriculture, Agricultural Research Service, National Animal Disease Center, Ames, Iowa, United States of America.
PLoS One. 2014 Jan 21;9(1):e85866. doi: 10.1371/journal.pone.0085866. eCollection 2014.
In recent studies, we demonstrated that a deletion of hha caused increased secretion of locus of enterocyte encoded adherence proteins and reduced motility of enterohemorrhagic Escherichia coli (EHEC) O157:H7. In addition to the importance of hha in positive regulation of motility, a two-component quorum sensing pathway encoded by the qseBC genes has been shown to activate bacterial motility in response to mammalian stress hormones epinephrine and norepinephrine as well as bacterially produced autoinducer-3. In this study, we compared regulatory contribution and hierarchy of hha, a member of the Hha/YmoA family of nucleoid-associated proteins, to that of qseBC in the expression of EHEC O157:H7 motility. Since norepinephrine affects motility of EHEC O157:H7 through a qseBC-encoded two-component quorum sensing signaling, we also determined whether the hha-mediated regulation of motility is affected by norepinephrine and whether this effect is qseBC dependent. We used single (Δhha or ΔqseC) and double (Δhha ΔqseC) deletion mutants to show that hha exerts a greater positive regulatory effect in comparison to qseBC on the expression of motility by EHEC O157:H7. We also show that Hha is hierarchically superior in transcriptional regulation of motility than QseBC because transcription of qseC was significantly reduced in the hha deletion mutant compared to that in the parental and the hha-complemented mutant strains. These results suggest that hha regulates motility of EHEC O157:H7 directly as well as indirectly by controlling the transcription of qseBC.
在最近的研究中，我们证明hha基因的缺失会导致肠细胞编码黏附蛋白位点的分泌增加，并降低肠出血性大肠杆菌（EHEC）O157:H7的运动性。除了hha在运动性正调控中的重要性外，由qseBC基因编码的双组分群体感应途径已被证明可响应哺乳动物应激激素肾上腺素和去甲肾上腺素以及细菌产生的自诱导物3来激活细菌运动性。在本研究中，我们比较了类核相关蛋白Hha/YmoA家族成员hha与qseBC在EHEC O157:H7运动性表达中的调控作用及层次关系。由于去甲肾上腺素通过qseBC编码的双组分群体感应信号影响EHEC O157:H7的运动性，我们还确定了hha介导的运动性调控是否受去甲肾上腺素影响以及这种影响是否依赖于qseBC。我们使用单缺失（Δhha或ΔqseC）和双缺失（Δhha ΔqseC）突变体表明，与qseBC相比，hha对EHEC O157:H7运动性表达具有更大的正调控作用。我们还表明，在运动性的转录调控方面，Hha在层次上高于QseBC，因为与亲本菌株和hha互补突变体菌株相比，hha缺失突变体中qseC的转录显著降低。这些结果表明，hha通过直接以及间接控制qseBC的转录来调节EHEC O157:H7的运动性。
