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Published on: March 9, 2014
Complementation of bacterial SecE by a chloroplastic homologue
L Fröderberg1, T Röhl, K J van Wijk
1Department of Biochemistry and Biophysics, Stockholm University, Sweden.
Chloroplastic SecE (cpSecE) functionally replaces bacterial SecE in protein translocation. This suggests thylakoid membranes possess a bacterial-like Sec translocase, highlighting evolutionary links.
Area of Science:
- Cellular biology
- Molecular biology
- Evolutionary biology
Background:
- SecE is vital for bacterial protein translocation via the SecAYE-translocase.
- A homologous protein, chloroplastic SecE (cpSecE), exists in thylakoid membranes but its function is unknown.
Purpose of the Study:
- To experimentally determine the function of cpSecE in vivo.
- To investigate if cpSecE can substitute for bacterial SecE.
Main Methods:
- Depletion of bacterial SecE in cells.
- Assessing growth, SecY stabilization, and Sec-dependent translocation in the presence of cpSecE.
Main Results:
- cpSecE supported growth in bacteria lacking native SecE.
- cpSecE stabilized the SecY component of the translocase.
- cpSecE facilitated Sec-dependent protein translocation.
Conclusions:
- cpSecE can functionally replace bacterial SecE in vivo.
- Thylakoid membranes likely contain a SecAYE-like translocase.
- This finding reinforces the evolutionary connection between chloroplasts and bacteria.
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