Details

Autor(en) / Beteiligte

• Draycheva, Albena
• Bornemann, Thomas
• Ryazanov, Sergey
• Lakomek, Nils‐Alexander
• Wintermeyer, Wolfgang

Titel

The bacterial SRP receptor, FtsY, is activated on binding to the translocon

Ist Teil von

• Molecular microbiology, 2016-10, Vol.102 (1), p.152-167

Ort / Verlag

England: Blackwell Publishing Ltd

Erscheinungsjahr

2016

Quelle

Wiley Online Library - AutoHoldings Journals

Beschreibungen/Notizen

• Summary Proteins are inserted into the bacterial plasma membrane cotranslationally after translating ribosomes are targeted to the translocon in the membrane via the signal recognition particle (SRP) pathway. The targeting pathway involves an interaction between SRP and the SRP receptor, FtsY. Here we focus on the role of FtsY and its interaction with the translocon in controlling targeting. We show that in unbound FtsY the NG and A domains interact with one another. The interaction involves the membrane‐targeting region at the junction between A and N domain. The closed form of FtsY is impaired in binding to SRP. Upon binding to the phospholipid‐embedded translocon the domains of FtsY move apart. This enhances the docking of the FtsY NG domain to the homologous NG domain of the SRP protein Ffh. Thus, FtsY binding to the translocon has a central role in orchestrating the formation of a quaternary transfer complex in which the nascent peptide is transferred to the translocon. We propose that FtsY activation at the translocon ensures that ribosome–SRP complexes are directed to available translocons. This way sequestering SRP in futile complexes with unbound FtsY can be avoided and efficient targeting to the translocon achieved. Cotranslational membrane targeting of ribosomes by the signal recognition particle (SRP) pathway in bacteria involves an interaction of the SRP protein Ffh and the SRP receptor, FtsY, through their homologous NG domains. SRP is activated on the ribosome by exposing the NG domain. Here we show that the activation for targeting complex formation is symmetric in that the NG domain of FtsY is exposed on binding to the translocon in a phospholipid environment.