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Functional interaction of chloroplast SRP/FtsY with the ALB3 translocase in thylakoids

Authors :
Hiroki Mori
Misty Moore
Robyn L. Goforth
Ralph Henry
Source :
The Journal of Cell Biology
Publication Year :
2003
Publisher :
Rockefeller University Press, 2003.

Abstract

Integration of thylakoid proteins by the chloroplast signal recognition particle (cpSRP) posttranslational transport pathway requires the cpSRP, an SRP receptor homologue (cpFtsY), and the membrane protein ALB3. Similarly, Escherichia coli uses an SRP and FtsY to cotranslationally target membrane proteins to the SecYEG translocase, which contains an ALB3 homologue, YidC. In neither system are the interactions between soluble and membrane components well understood. We show that complexes containing cpSRP, cpFtsY, and ALB3 can be precipitated using affinity tags on cpSRP or cpFtsY. Stabilization of this complex with GMP-PNP specifically blocks subsequent integration of substrate (light harvesting chl a/b-binding protein [LHCP]), indicating that the complex occupies functional ALB3 translocation sites. Surprisingly, neither substrate nor cpSRP43, a component of cpSRP, was necessary to form a complex with ALB3. Complexes also contained cpSecY, but its removal did not inhibit ALB3 function. Furthermore, antibody bound to ALB3 prevented ALB3 association with cpSRP and cpFtsY and inhibited LHCP integration suggesting that a complex containing cpSRP, cpFtsY, and ALB3 must form for proper LHCP integration.

Details

ISSN :
15408140 and 00219525
Volume :
162
Database :
OpenAIRE
Journal :
Journal of Cell Biology
Accession number :
edsair.doi.dedup.....49d89e4da1e0ea1b9c0df39f1ea4a2a2
Full Text :
https://doi.org/10.1083/jcb.200307067