Immune recognition of pathogen-associated molecular patterns (PAMPs) by pattern recognition receptors often activates proinflammatory NF-κB signalling1. Recent studies indicate that the bacterial metabolite d-glycero-β-d-manno-heptose 1,7-bisphosphate (HBP) can activate NF-κB signalling in host cytosol2–4, but it is unclear whether HBP is a genuine PAMP and the cognate pattern recognition receptor has not been identified. Here we combined a transposon screen in Yersinia pseudotuberculosis with biochemical analyses and identified ADP-β-d-manno-heptose (ADP-Hep), which mediates type III secretion system-dependent NF-κB activation and cytokine expression. ADP-Hep, but not other heptose metabolites, could enter host cytosol to activate NF-κB. A CRISPR–Cas9 screen showed that activation of NF-κB by ADP-Hep involves an ALPK1 (alpha-kinase 1)–TIFA (TRAF-interacting protein with forkhead-associated domain) axis. ADP-Hep directly binds the N-terminal domain of ALPK1, stimulating its kinase domain to phosphorylate and activate TIFA. The crystal structure of the N-terminal domain of ALPK1 and ADP-Hep in complex revealed the atomic mechanism of this ligand–receptor recognition process. HBP was transformed by host adenylyltransferases into ADP-heptose 7-P, which could activate ALPK1 to a lesser extent than ADP-Hep. ADP-Hep (but not HBP) alone or during bacterial infection induced Alpk1-dependent inflammation in mice. Our findings identify ALPK1 and ADP-Hep as a pattern recognition receptor and an effective immunomodulator, respectively.The bacterial metabolite ADP-heptose activates NF-κB in host cells via alpha-kinase 1 and the TIFA–TRAF signalling pathway.

中文翻译：

---

α-激酶 1 是细菌 ADP-庚糖的细胞溶质先天免疫受体

模式识别受体对病原体相关分子模式 (PAMP) 的免疫识别通常会激活促炎性 NF-κB 信号传导 1。最近的研究表明，细菌代谢物 d-glycero-β-d-manno-heptose 1,7-bisphosphate (HBP) 可以激活宿主细胞溶胶 2-4 中的 NF-κB 信号传导，但尚不清楚 HBP 是否是真正的 PAMP 以及同源模式识别受体尚未确定。在这里，我们将假结核耶尔森氏菌的转座子筛选与生化分析相结合，并鉴定了 ADP-β-d-甘露庚糖 (ADP-Hep)，其介导 III 型分泌系统依赖性 NF-κB 激活和细胞因子表达。ADP-Hep，而不是其他庚糖代谢物，可以进入宿主细胞质以激活 NF-κB。CRISPR-Cas9 筛选显示 ADP-Hep 对 NF-κB 的激活涉及 ALPK1（α-激酶 1）-TIFA（具有叉头相关结构域的 TRAF 相互作用蛋白）轴。ADP-Hep 直接结合 ALPK1 的 N 端结构域，刺激其激酶结构域磷酸化并激活 TIFA。ALPK1 和 ADP-Hep 复合物的 N 端结构域的晶体结构揭示了这种配体 - 受体识别过程的原子机制。HBP 被宿主腺苷酸转移酶转化为 ADP-庚糖 7-P，其对 ALPK1 的激活程度低于 ADP-Hep。ADP-Hep（但不是 HBP）单独或在细菌感染期间诱导小鼠的 Alpk1 依赖性炎症。我们的研究结果将 ALPK1 和 ADP-Hep 分别确定为模式识别受体和有效的免疫调节剂。