Autorepressor PsrA is required for optimal Legionella pneumophila growth in Acanthamoeba castellanii protozoa,Molecular Microbiology

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Autorepressor PsrA is required for optimal Legionella pneumophila growth in Acanthamoeba castellanii protozoa
Molecular Microbiology ( IF 2.6 ) Pub Date : 2021-05-20 , DOI: 10.1111/mmi.14760
Christopher I Graham ₁ , Palak G Patel ₁ , Jennifer R Tanner ₁ , Jacqueline Hellinga ₁ , Teassa L MacMartin ₁ , Georg Hausner ₁ , Ann Karen C Brassinga ₁

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Legionella pneumophila possesses a unique intracellular lifecycle featuring distinct morphological stages that include replicative forms and transmissive cyst forms. Expression of genes associated with virulence traits and cyst morphogenesis is concomitant, and governed by a complex stringent response based-regulatory network and the stationary phase sigma factor RpoS. In Pseudomonas spp., rpoS expression is controlled by the autorepressor PsrA, and orthologs of PsrA and RpoS are required for cyst formation in Azotobacter. Here we report that the L. pneumophila psrA ortholog, expressed as a leaderless monocistronic transcript, is also an autorepressor, but is not a regulator of rpoS expression. Further, the binding site sequence recognized by L. pneumophila PsrA is different from that of Pseudomonas PsrA, suggesting a repertoire of target genes unique to L. pneumophila. While PsrA was dispensable for growth in human U937-derived macrophages, lack of PsrA affected bacterial intracellular growth in Acanthamoeba castellanii protozoa, but also increased the quantity of poly-3-hydroxybutyrate (PHB) inclusions in matured transmissive cysts. Interestingly, overexpression of PsrA increased the size and bacterial load of the replicative vacuole in both host cell types. Taken together, we report that PsrA is a host-specific requirement for optimal temporal progression of L. pneumophila intracellular lifecycle in A. castellanii.

中文翻译：

Autorepressor PsrA 是 Acanthamoeba castellanii 原生动物中嗜肺军团菌最佳生长所必需的

嗜肺军团菌具有独特的细胞内生命周期，具有不同的形态阶段，包括复制形式和传播性囊肿形式。与毒力性状和胞囊形态发生相关的基因的表达是伴随的，并受基于复杂严格响应的调节网络和固定相 sigma 因子 RpoS 的控制。在假单胞菌属中，rpoS表达受自阻抑物 PsrA 控制，而 PsrA 和 RpoS 的直向同源物是固氮菌中囊肿形成所必需的。在这里我们报告L. pneumophila psrA直向同源物，表达为无前导单顺反子转录物，也是一种自动抑制因子，但不是rpoS的调节剂表达。此外，通过识别的结合位点序列嗜肺PsrA不同于不同假单胞菌PsrA，提示特有的靶基因的所有组成成分嗜肺军团菌。虽然 PsrA 对人类 U937 衍生的巨噬细胞的生长是可有可无的，但缺乏 PsrA 会影响卡氏棘阿米巴原生动物的细菌细胞内生长，但也会增加成熟的透射包囊中聚 3-羟基丁酸 (PHB) 内含物的数量。有趣的是，PsrA 的过表达增加了两种宿主细胞类型中复制液泡的大小和细菌负荷。总之，我们报告说 PsrA 是嗜肺军团菌最佳时间进展的宿主特定要求A 中的细胞内生命周期。阿米巴。

更新日期：2021-05-20

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