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Publication Abstract from PubMed

Energy-coupling factor (ECF)-type transporters mediate the uptake of micronutrients in many bacteria. They consist of a substrate-translocating subunit (S-component) and an ATP-hydrolysing motor (ECF module) Previous data indicate that the S-component topples within the membrane to alternately expose the binding site to either side of the membrane. In many ECF transporters, the substrate-free S-component can be expelled from the ECF module. Here we study this enigmatic expulsion step by cryogenic electron microscopy and reveal that ATP induces a concave-to-convex shape change of two long helices in the motor, thereby destroying the S-component's docking site and allowing for its dissociation. We show that adaptation of the membrane morphology to the conformational state of the motor may favour expulsion of the substrate-free S-component when ATP is bound and docking of the substrate-loaded S-component after hydrolysis. Our work provides a picture of bilayer-assisted chemo-mechanical coupling in the transport cycle of ECF transporters.

Expulsion mechanism of the substrate-translocating subunit in ECF transporters.,Thangaratnarajah C, Nijland M, Borges-Araujo L, Jeucken A, Rheinberger J, Marrink SJ, Souza PCT, Paulino C, Slotboom DJ Nat Commun. 2023 Jul 25;14(1):4484. doi: 10.1038/s41467-023-40266-1. PMID:37491368^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.