The dCache Chemoreceptor TlpA of Helicobacter pylori Binds Multiple Attractant and Antagonistic Ligands via Distinct Sites.
The dCache Chemoreceptor TlpA of Helicobacter pylori Binds Multiple Attractant and Antagonistic Ligands via Distinct Sites.
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DOI：
10.1128/mbio.01819-21
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发表时间：
2021-08-31
期刊：
影响因子：
6.4
通讯作者：
Ottemann KM
中科院分区：
文献类型：
--
作者：
Johnson KS;Elgamoudi BA;Jen FE;Day CJ;Sweeney EG;Pryce ML;Guillemin K;Haselhorst T;Korolik V;Ottemann KM
幽门螺杆菌化学受体TlpA在慢性胃定植期间抑制宿主炎症中起作用。TlpA具有周质dCache_1结构域，其是能够感测许多配体的结构;然而，唯一表征的TlpA信号是精氨酸、碳酸氢盐和酸。为了增加我们对TlpA的感测特征的理解，我们使用配体结合阵列筛选不同的TlpA配体。TlpA结合7个配体的亲和力在低至中等微摩尔范围内。这些配体，精氨酸，富马酸，和半胱氨酸，TlpA依赖性的化学引诱剂，而其他引起没有反应。分子对接实验，定点突变，和竞争表面等离子体共振结合试验表明，TlpA通过膜远端和近端dCache_1结合口袋结合配体。令人惊讶的是，一个非活性配体，葡糖胺，作为一种趋化性拮抗剂，防止趋化反应的趋化性配体，并采取行动，以阻止配体的结合，无论他们是否结合膜远端或近端dCache_1亚结构域。总之，这些结果表明，TlpA的感觉多个引诱配体以及拮抗剂，一个新兴的主题在趋化系统。
The Helicobacter pylori chemoreceptor TlpA plays a role in dampening host inflammation during chronic stomach colonization. TlpA has a periplasmic dCache_1 domain, a structure that is capable of sensing many ligands; however, the only characterized TlpA signals are arginine, bicarbonate, and acid. To increase our understanding of TlpA’s sensing profile, we screened for diverse TlpA ligands using ligand binding arrays. TlpA bound seven ligands with affinities in the low- to middle-micromolar ranges. Three of these ligands, arginine, fumarate, and cysteine, were TlpA-dependent chemoattractants, while the others elicited no response. Molecular docking experiments, site-directed point mutants, and competition surface plasmon resonance binding assays suggested that TlpA binds ligands via both the membrane-distal and -proximal dCache_1 binding pockets. Surprisingly, one of the nonactive ligands, glucosamine, acted as a chemotaxis antagonist, preventing the chemotaxis response to chemoattractant ligands, and acted to block the binding of ligands irrespective of whether they bound the membrane-distal or -proximal dCache_1 subdomains. In total, these results suggest that TlpA senses multiple attractant ligands as well as antagonist ones, an emerging theme in chemotaxis systems.