Multiple detection of both attractants and repellents by the dCache ‐chemoreceptor SO_1056 of Shewanella oneidensis

Anne Boyeldieu (1) , Jean‐pierre Poli (2, 1) , Amine Ali Chaouche (1) , Henri‐pierre Fierobe (3) , Marie‐thérèse Giudici-Orticoni (1) , Vincent Méjean (1) , Cécile Jourlin‐castelli (1)

1 BIP - Bioénergétique et Ingénierie des Protéines
2 Università di Corsica Pasquale Paoli [Université de Corse Pascal Paoli]
3 LCB - Laboratoire de chimie bactérienne

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 lM for L-malate and of 47.7 lM 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.

Mots clés: bacterial chemotaxis; chemoreceptors; dCache domain; isothermal titration calorimetry; ligand binding; thermal shift assay

Domaines: Bactériologie

Anne Boyeldieu, Jean‐pierre Poli, Amine Ali Chaouche, Henri‐pierre Fierobe, Marie‐thérèse Giudici-Orticoni, et al.. Multiple detection of both attractants and repellents by the dCache ‐chemoreceptor SO_1056 of Shewanella oneidensis. FEBS Journal, In press, ⟨10.1111/febs.16548⟩. ⟨hal-03740302⟩