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Updated: Mar 18, 2026

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Published on: March 16, 2022
Electrostatics and Intrinsic Disorder Drive Translocon Binding of the SRP Receptor FtsY
Nils-Alexander Lakomek1,2, Albena Draycheva3, Thomas Bornemann3
1Department of NMR-based Structural Biology, Max-Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany. nils-alexander.lakomek@phys.chem.ethz.ch.
Abstract:
Integral membrane proteins in bacteria are co-translationally targeted to the SecYEG translocon for membrane insertion via the signal recognition particle (SRP) pathway. The SRP receptor FtsY and its N-terminal A domain, which is lacking in any structural model of FtsY, were studied using NMR and fluorescence spectroscopy. The A domain is mainly disordered and highly flexible; it binds to lipids via its N terminus and the C-terminal membrane targeting sequence. The central A domain binds to the translocon non-specifically and maintains disorder. Translocon targeting and binding of the A domain is driven by electrostatic interactions. The intrinsically disordered A domain tethers FtsY to the translocon, and because of its flexibility, allows the FtsY NG domain to scan a large area for binding to the NG domain of ribosome-bound SRP, thereby promoting the formation of the quaternary transfer complex at the membrane.
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