SRP-dependent co-translational targeting and SecA-dependent translocation analyzed as individual steps in the export of a bacterial protein
Open Access
- 1 December 2000
- journal article
- research article
- Published by Springer Nature in The EMBO Journal
- Vol. 19 (23), 6419-6426
- https://doi.org/10.1093/emboj/19.23.6419
Abstract
Recently it has been recognized that the signal recognition particle (SRP) of Escherichia coli represents a specific targeting device for hydrophobic inner membrane proteins. It has remained unclear, however, whether the bacterial SRP functions in concert with SecA, which is required for the translocation of secretory proteins across the inner membrane. Here, we have analyzed a hybrid protein constructed by fusing the signal anchor sequence of an SRP‐dependent inner membrane protein (MtlA) to the mature part of an exclusively SecA‐requiring secretory protein (OmpA). We show that the signal anchor sequence of MtlA confers the novel properties onto nascent chains of OmpA of being co‐translationally recognized and targeted to SecY by SRP. Once targeted to SecY, ribosome‐associated nascent chains of the hybrid protein, however, remain untranslocated unless SecA is present. These results indicate that SRP and SecA cooperate in a sequential, non‐overlapping manner in the topogenesis of those membrane proteins which, in addition to a signal anchor sequence, harbor a substantial hydrophilic domain to be translocated into the periplasm.Keywords
This publication has 31 references indexed in Scilit:
- Nascent Lep inserts into the Escherichia coli inner membrane in the vicinity of YidC, SecY and SecAFEBS Letters, 2000
- The Translocon: A Dynamic Gateway at the ER MembraneAnnual Review of Cell and Developmental Biology, 1999
- A Site-specific, Membrane-dependent Cleavage Event Defines the Membrane Binding Domain of FtsYPublished by Elsevier ,1999
- Nascent membrane and presecretory proteins synthesized in Escherichia coli associate with signal recognition particle and trigger factorMolecular Microbiology, 1997
- Assembly of a cytoplasmic membrane protein in Escherichia coli is dependent on the signal recognition particleFEBS Letters, 1996
- A posttargeting signal sequence recognition event in the endoplasmic reticulum membraneCell, 1995
- SecA promotes preprotein translocation by undergoing ATP-driven cycles of membrane insertion and deinsertionCell, 1994
- Secretory proteins move through the endoplasmic reticulum membrane via an aqueous, gated poreCell, 1994
- The signal sequence moves through a ribosomal tunnel into a noncytoplasmic aqueous environment at the ER membrane early in translocationCell, 1993
- A signal recognition particle in Escherichia coli?Current Biology, 1993