期刊
FEBS JOURNAL
卷 289, 期 21, 页码 6752-6766出版社
WILEY
DOI: 10.1111/febs.16548
关键词
bacterial chemotaxis; chemoreceptors; dCache domain; isothermal titration calorimetry; ligand binding; thermal shift assay
资金
- Centre National de la Recherche Scientifique
- Aix-Marseille Universite
- HTS-BIO [152 660]
- MESR fellowship
- ATER position (Aix-Marseille Universite)
- Universite de Corse Pasquale Paoli
- ProjektDEAL
Chemoreceptors are transmembrane proteins that detect compound gradients or signals in the surroundings of bacteria. MCP SO_1056 from Shewanella oneidensis can bind chromate and detect l-malate as an attractant, as well as nickel and cobalt as repellents.
Chemoreceptors are usually transmembrane proteins dedicated to the detection of compound gradients or signals in the surroundings of a bacterium. After detection, they modulate the activation of CheA-CheY, the core of the chemotactic pathway, to allow cells to move upwards or downwards depending on whether the signal is an attractant or a repellent, respectively. Environmental bacteria such as Shewanella oneidensis harbour dozens of chemoreceptors or MCPs (methyl-accepting chemotaxis proteins). A recent study revealed that MCP SO_1056 of S. oneidensis binds chromate. Here, we show that this MCP also detects an additional attractant (l-malate) and two repellents (nickel and cobalt). The experiments were performed in vivo by the agarose-in-plug technique after overproducing MCP SO_1056 and in vitro, when possible, by submitting the purified ligand-binding domain (LBD) of SO_1056 to a thermal shift assay (TSA) coupled to isothermal titration calorimetry (ITC). ITC assays revealed a K-D of 3.4 mu m for l-malate and of 47.7 mu m for nickel. We conclude that MCP SO_1056 binds attractants and repellents of unrelated composition. The LBD of SO_1056 belongs to the double Cache_1 family and is highly homologous to PctA, a chemoreceptor from Pseudomonas aeruginosa that detects several amino acids. Therefore, LBDs of the same family can bind diverse compounds, confirming that experimental approaches are required to define accurate LBD-binding molecules or signals.
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