Department of Microbiology, Monash University, Melbourne, Australia.
mBio. 2010 Aug 17;1(3):e00112-10. doi: 10.1128/mBio.00112-10.
Despite recent advances in our understanding of how Helicobacter pylori causes disease, the factors that allow this pathogen to persist in the stomach have not yet been fully characterized. To identify new virulence factors in H. pylori, we generated low-infectivity variants of a mouse-colonizing H. pylori strain using the classical technique of in vitro attenuation. The resulting variants and their highly infectious progenitor bacteria were then analyzed by global gene expression profiling. The gene expression levels of five open reading frames (ORFs) were significantly reduced in low-infectivity variants, with the most significant changes observed for ORFs HP1583 and HP1582. These ORFs were annotated as encoding homologs of the Escherichia coli vitamin B(6) biosynthesis enzymes PdxA and PdxJ. Functional complementation studies with E. coli confirmed H. pylori PdxA and PdxJ to be bona fide homologs of vitamin B(6) biosynthesis enzymes. Importantly, H. pylori PdxA was required for optimal growth in vitro and was shown to be essential for chronic colonization in mice. In addition to having a well-known metabolic role, vitamin B(6) is necessary for the synthesis of glycosylated flagella and for flagellum-based motility in H. pylori. Thus, for the first time, we identify vitamin B(6) biosynthesis enzymes as novel virulence factors in bacteria. Interestingly, pdxA and pdxJ orthologs are present in a number of human pathogens, but not in mammalian cells. We therefore propose that PdxA/J enzymes may represent ideal candidates for therapeutic targets against bacterial pathogens.
尽管我们对幽门螺杆菌如何引起疾病的理解有了最近的进展，但允许这种病原体在胃中持续存在的因素尚未得到充分描述。为了鉴定幽门螺杆菌中的新毒力因子，我们使用体外减毒的经典技术生成了一种具有低感染力的小鼠定植幽门螺杆菌株的变体。然后通过全基因表达谱分析对产生的变体及其高感染力的原始细菌进行分析。五个开放阅读框（ORF）的基因表达水平在低感染力变体中显著降低，其中 ORF HP1583 和 HP1582 的变化最为显著。这些 ORF 被注释为编码大肠杆菌维生素 B(6)生物合成酶 PdxA 和 PdxJ 的同源物。与大肠杆菌的功能互补研究证实了幽门螺杆菌 PdxA 和 PdxJ 是维生素 B(6)生物合成酶的真正同源物。重要的是，幽门螺杆菌 PdxA 是体外最佳生长所必需的，并被证明对小鼠慢性定植是必需的。除了具有众所周知的代谢作用外，维生素 B(6)是糖基化鞭毛合成和幽门螺杆菌鞭毛运动所必需的。因此，我们首次将维生素 B(6)生物合成酶鉴定为细菌的新型毒力因子。有趣的是，pdxA 和 pdxJ 同源物存在于许多人类病原体中，但不存在于哺乳动物细胞中。因此，我们提出 PdxA/J 酶可能是针对细菌病原体的治疗靶点的理想候选物。
