The substrate-binding domains of the osmoregulatory ABC importer OpuA transiently interact

• Verfasst von: Noort, Marco van den [VerfasserIn]
• Verfasst von: Drougkas, Panagiotis [VerfasserIn]
• Verfasst von: Batista Paulino, Cristina [VerfasserIn]
• Verfasst von: Poolman, Bert [VerfasserIn]
• Titel: The substrate-binding domains of the osmoregulatory ABC importer OpuA transiently interact
• Verf.angabe: Marco van den Noort, Panagiotis Drougkas, Cristina Paulino, Bert Poolman
• E-Jahr: 2024
• Jahr: 02 May 2024
• Umfang: 25 S.
• Illustrationen: Illustrationen
• Fussnoten: Gesehen am 09.12.2024
• Titel Quelle: Enthalten in: eLife
• Ort Quelle: Cambridge : eLife Sciences Publications, 2012
• Jahr Quelle: 2024
• Band/Heft Quelle: 12(2024), Artikel-ID RP90996, Seite 1-25
• ISSN Quelle: 2050-084X
• DOI: doi:10.7554/eLife.90996
• Datenträger: Online-Ressource
• Sprache: eng
• Sach-SW: ABC importer
• Sach-SW: interdomain dynamics
• Sach-SW: osmoregulatory transporter
• Sach-SW: single-molecule FRET
• Sach-SW: single-particle cryo-EM
• Sach-SW: transient protein-protein interactons
• K10plus-PPN: 1911206443

Abstract

Bacteria utilize various strategies to prevent internal dehydration during hypertonic stress. A common approach to countering the effects of the stress is to import compatible solutes such as glycine betaine, leading to simultaneous passive water fluxes following the osmotic gradient. OpuA from Lactococcus lactis is a type I ABC-importer that uses two substrate-binding domains (SBDs) to capture extracellular glycine betaine and deliver the substrate to the transmembrane domains for subsequent transport. OpuA senses osmotic stress via changes in the internal ionic strength and is furthermore regulated by the 2nd messenger cyclic-di-AMP. We now show, by means of solution-based single-molecule FRET and analysis with multi-parameter photon-by-photon hidden Markov modeling, that the SBDs transiently interact in an ionic strength-dependent manner. The smFRET data are in accordance with the apparent cooperativity in transport and supported by new cryo-EM data of OpuA. We propose that the physical interactions between SBDs and cooperativity in substrate delivery are part of the transport mechanism.