Posttranslational insertion of small membrane proteins by the bacterial signal recognition particle

by Ruth Steinberg, Andrea Origi, Ana Natriashvili, Pinku Sarmah, Mariya Licheva, Princess M. Walker, Claudine Kraft, Stephen High, Joen Luirink, Wei. Q. Shi, Martin Helmstädter, Maximilian H. Ulbrich, Hans-Georg Koch

Small membrane proteins represent a largely unexplored yet abundant class of proteins in pro- and eukaryotes. They essentially consist of a single transmembrane domain and are associated with stress response mechanisms in bacteria. How these proteins are inserted into the bacterial membrane is unknown. Our study revealed that in Escherichia coli, the 27-amino-acid-long model protein YohP is recognized by the signal recognition particle (SRP), as indicated by in vivo and in vitro site-directed cross-linking. Cross-links to SRP were also observed for a second small membrane protein, the 33-amino-acid-long YkgR. However, in contrast to the canonical cotranslational recognition by SRP, SRP was found to bind to YohP posttranslationally. In vitro protein transport assays in the presence of a SecY inhibitor and proteoliposome studies demonstrated that SRP and its receptor FtsY are essential for the posttranslational membrane insertion of YohP by either the SecYEG translocon or by the YidC insertase. Furthermore, our data showed that the yohP mRNA localized preferentially and translation-independently to the bacterial membrane in vivo. In summary, our data revealed that YohP engages an unique SRP-dependent posttranslational insertion pathway that is likely preceded by an mRNA targeting step. This further highlights the enormous plasticity of bacterial protein transport machineries.

Paper source

Make more money selling and advertising your products and services for free on Ominy market. Click here to start selling now

Plos Journal

READ MORE  Cardiac and renal function interactions in heart failure with reduced ejection fraction: A mathematical modeling analysis

Ominy science editory team

A team of dedicated users that search, fetch and publish research stories for Ominy science.

Enable notifications of new posts    OK No thanks