Microbiota generates millimolar concentrations of short-chain fatty acids (SCFAs) that can modulate host metabolism, immunity and susceptibility to infection. Butyrate in particular can function as a carbon source and anti-inflammatory metabolite, but the mechanism by which it inhibits pathogen virulence has been elusive. Using chemical proteomics, we found that several virulence factors encoded by Salmonella pathogenicity island-1 (SPI-1) are acylated by SCFAs. Notably, a transcriptional regulator of SPI-1, HilA, was acylated on several key lysine residues. Subsequent incorporation of stable butyryl-lysine analogs using CRISPR-Cas9 gene editing and unnatural amino acid mutagenesis revealed that site-specific modification of HilA impacts its genomic occupancy, expression of SPI-1 genes and attenuates Salmonella enterica serovar Typhimurium invasion of epithelial cells, as well as dissemination in vivo. Moreover, a multiple-site HilA lysine acylation mutant strain of S. Typhimurium was resistant to butyrate inhibition ex vivo and microbiota attenuation in vivo. Our results suggest that prominent microbiota-derived metabolites may directly acylate virulence factors to inhibit microbial pathogenesis in vivo.

中文翻译：

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细菌毒力调节剂的位点特异性酰化减弱了感染。

微生物群产生毫摩尔浓度的短链脂肪酸 (SCFA)，可以调节宿主的新陈代谢、免疫力和对感染的易感性。丁酸盐尤其可以充当碳源和抗炎代谢物，但它抑制病原体毒力的机制一直难以捉摸。使用化学蛋白质组学，我们发现沙门氏菌致病性岛 1 (SPI-1) 编码的几种毒力因子被 SCFA 酰化。值得注意的是，SPI-1 的转录调节因子 HilA 在几个关键的赖氨酸残基上被酰化。随后使用 CRISPR-Cas9 基因编辑和非天然氨基酸诱变掺入稳定的丁酰赖氨酸类似物表明，HilA 的位点特异性修饰会影响其基因组占有率，SPI-1 基因的表达并减弱鼠伤寒沙门氏菌对上皮细胞的侵袭，以及体内传播。此外，鼠伤寒沙门氏菌的多位点 HilA 赖氨酸酰化突变株对体外丁酸盐抑制和体内微生物群衰减具有抗性。我们的研究结果表明，显着的微生物群衍生代谢物可能直接酰化毒力因子以抑制体内微生物发病机制。