Elucidation of the RamA regulon in Klebsiella pneumoniae reveals a role in LPS regulation.
Elucidation of the RamA regulon in Klebsiella pneumoniae reveals a role in LPS regulation.
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在肺炎克雷伯氏菌中阐明拉玛法规揭示了在LPS调节中的作用。
DOI：
10.1371/journal.ppat.1004627
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发表时间：
2015-01
期刊：
影响因子：
6.7
通讯作者：
Schneiders T
中科院分区：
文献类型：
--
作者：
De Majumdar S;Yu J;Fookes M;McAteer SP;Llobet E;Finn S;Spence S;Monahan A;Monaghan A;Kissenpfennig A;Ingram RJ;Bengoechea J;Gally DL;Fanning S;Elborn JS;Schneiders T
肺炎克雷伯菌是一种重要的人类病原体，部分原因是多药耐药率高。RAMA是肺炎克雷伯菌中的一种内在调节因子，被证实对细菌对抗菌素挑战的反应具有重要作用；然而，人们对其在感染期间可能在该微生物中发挥的更广泛的调节作用知之甚少。在这项工作中，我们证明了RAMA是一个全球转录调节因子，它显著扰乱肺炎克雷伯菌的转录格局，导致微生物-药物或微生物-宿主反应的改变。这在很大程度上是由于与无数细胞功能相关的68个基因的直接调控。重要的是，RAMA直接结合并激活与脂类A生物合成相关的lpxC、lpxL-2和lpxO基因，从而导致脂多糖中脂类A部分的修饰。RAMA介导的改变降低了对粘菌素E、多粘菌素B和人阳离子抗菌肽LL-37的敏感性。RAMA水平的增加减少了肺炎克雷伯菌对巨噬细胞的黏附和摄取，这一点得到了体内感染研究的支持，这些研究表明，过量表达肺炎克雷伯菌的RAMA增加了全身传播。这些数据表明，RAMA介导的调节直接扰乱微生物的表面特性，包括脂类A的生物合成，这有助于逃避固有的宿主反应。这突显了RAMA作为一种全球调节因子，赋予了病原性适应表型，这对于我们理解肠杆菌、沙门氏菌和柠檬酸杆菌的发病机制具有重要意义。表达同源的RAMA蛋白。细菌可以在抗生素压力下快速进化，产生耐药性，这种情况发生在目标基因突变或耐药性编码基因转移时。或者，微生物可以简单地改变内在蛋白质的水平，从而使有机体“争取”时间来抵抗抗生素的压力。肺炎克雷伯菌是一种能引起严重血流或呼吸道感染的病原体，但更重要的是，越来越多的报告显示，这种细菌具有多重耐药性。我们的数据表明，RAMA可以触发细菌表面的变化，使克雷伯菌能够在抗生素挑战、宿主免疫肽的降解和抵抗吞噬的情况下存活。我们证明，针对宿主来源的因子，过度表达肺炎克雷伯菌的RAMA提高存活率的分子基础与RAMA驱动的克雷伯菌脂蛋白A部分的改变有关。这种修饰很可能与克雷伯氏菌抵抗宿主反应的能力有关，从而使其保持不被免疫系统检测到。我们工作的相关性超出了克雷伯氏菌中的RAMA作为其他病原体，如肠杆菌属和沙门氏菌属。也会产生这种蛋白质。因此，我们的主要结论是，内在调节因子RAMA扰乱了宿主-微生物和微生物-药物的相互作用。
Klebsiella pneumoniae is a significant human pathogen, in part due to high rates of multidrug resistance. RamA is an intrinsic regulator in K. pneumoniae established to be important for the bacterial response to antimicrobial challenge; however, little is known about its possible wider regulatory role in this organism during infection. In this work, we demonstrate that RamA is a global transcriptional regulator that significantly perturbs the transcriptional landscape of K. pneumoniae, resulting in altered microbe-drug or microbe-host response. This is largely due to the direct regulation of 68 genes associated with a myriad of cellular functions. Importantly, RamA directly binds and activates the lpxC, lpxL-2 and lpxO genes associated with lipid A biosynthesis, thus resulting in modifications within the lipid A moiety of the lipopolysaccharide. RamA-mediated alterations decrease susceptibility to colistin E, polymyxin B and human cationic antimicrobial peptide LL-37. Increased RamA levels reduce K. pneumoniae adhesion and uptake into macrophages, which is supported by in vivo infection studies, that demonstrate increased systemic dissemination of ramA overexpressing K. pneumoniae. These data establish that RamA-mediated regulation directly perturbs microbial surface properties, including lipid A biosynthesis, which facilitate evasion from the innate host response. This highlights RamA as a global regulator that confers pathoadaptive phenotypes with implications for our understanding of the pathogenesis of Enterobacter, Salmonella and Citrobacter spp. that express orthologous RamA proteins. Bacteria can rapidly evolve under antibiotic pressure to develop resistance, which occurs when target genes mutate, or when resistance-encoding genes are transferred. Alternatively, microbes can simply alter the levels of intrinsic proteins that allow the organism to “buy” time to resist antibiotic pressure. Klebsiella pneumoniae is a pathogen that causes significant blood stream or respiratory infections, but more importantly is a bacterium that is increasingly being reported as multidrug resistant. Our data demonstrate that RamA can trigger changes on the bacterial surface that allow Klebsiella to survive both antibiotic challenge, degradation by host immune peptides and resist phagocytosis. We demonstrate that the molecular basis of increased survival of ramA overexpressing K. pneumoniae, against host-derived factors is associated with RamA-driven alterations of the lipid A moiety of Klebsiella LPS. This modification is likely to be linked to Klebsiella’s ability to resist the host response so that it remains undetected by the immune system. The relevance of our work extends beyond RamA in Klebsiella as other pathogens such as Enterobacter spp and Salmonella spp. also produce this protein. Thus our overarching conclusion is that the intrinsic regulator, RamA perturbs host-microbe and microbe-drug interactions.
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影响因子：
3.2
作者：
Bennik, MHJ;Pomposiello, PJ;Demple, B
通讯作者：
Demple, B
DOI：
10.1006/bbrc.2002.6559
发表时间：
2002-03-08
影响因子：
3.1
作者：
Griffith, KL;Shah, IM;Wolf, RE
通讯作者：
Wolf, RE
影响因子：
3.4
作者：
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通讯作者：
Piddock, LJV
影响因子：
4.8
作者：
Clements, Abigail;Tull, Dedreia;Strugnell, Richard A.
通讯作者：
Strugnell, Richard A.
影响因子：
56.9
作者：
Hung, DT;Shakhnovich, EA;Mekalanos, JJ
通讯作者：
Mekalanos, JJ