Roles of Brucella abortus SpoT in morphological differentiation and intramacrophagic replication.
Roles of Brucella abortus SpoT in morphological differentiation and intramacrophagic replication.
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DOI：
10.1099/mic.0.27782-0
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发表时间：
2005-05
期刊：
影响因子：
1.5
通讯作者：
Suk Kim;Kenta Watanabe;Hiroshi Suzuki;M. Watarai
中科院分区：
文献类型：
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作者：
Suk Kim;Kenta Watanabe;Hiroshi Suzuki;M. Watarai
布鲁氏菌在宿主巨噬细胞内生存和复制的基本机制和毒力因素尚不完全清楚。作者之前曾报道，流产布鲁氏菌的推定鸟苷 5'-二磷酸 3'-二磷酸 (ppGpp) 突变体（spoT 突变体）未能在 HeLa 细胞中复制。本研究表明，spoT突变体的表面蛋白模式和形态变化与野生型流产布鲁氏菌不同。流产 B. abortus 野生型在用 ppGpp 合成酶 I 激活抑制剂处理后改变了其形态。在营养饥饿、一氧化氮抗性、酸抗性和抗生素抗性等胁迫条件下的各种测试中，spoT突变体的抗逆性低于野生型。尽管 spoT 突变体具有与流产布鲁氏菌野生型相同的平滑表型和 LPS 谱，但它对巨噬细胞的粘附率较高，但巨噬细胞内的内化和细胞内复制较低。 spoT 突变体不与晚期内体或溶酶体共定位，10 天后几乎从小鼠脾脏中清除，且没有脾肿大。 RT-PCR用于检测在低pH富集培养基中孵育的约10(6)个细胞的spoT mRNA；结果表明，孵育30分钟后spoT的表达增加。数据表明，SpoT 不会促进流产布鲁氏菌的细胞内运输，但有助于维持细菌形态和细胞内复制所需的生理适应。
The essential mechanisms and virulence factors enabling Brucella species to survive and replicate inside host macrophages are not fully understood. The authors previously reported that a putative guanosine 5'-diphosphate 3'-diphosphate (ppGpp) mutant (spoT mutant) of Brucella abortus failed to replicate in HeLa cells. The present study showed that the pattern of surface proteins and morphological change of the spoT mutant were different from B. abortus wild-type. B. abortus wild-type changed its morphology upon treatment with ppGpp synthetase I activation inhibitor. In various tests under stress conditions, including nutrient starvation, nitric oxide resistance, acid resistance and antibiotic resistance, the spoT mutant had a lower stress resistance than B. abortus wild-type. Although the spoT mutant has the same smooth phenotype and LPS profile as B. abortus wild-type, it had a higher rate of adherence to macrophages but lower internalization and intracellular replication within macrophages. The spoT mutant did not co-localize with either late endosomes or lysosomes and was almost cleared from the spleens of mice after 10 days, without splenomegaly. RT-PCR was used to detect spoT mRNA from around 10(6) cells incubated in low-pH enriched medium; it showed that the expression of spoT increased after 30 min incubation. The data suggest that SpoT does not contribute to intracellular trafficking of B. abortus, but contributes to the maintenance of bacterial morphology and the physiological adaptation required for intracellular replication.