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Conservative sorting in a primitive plastid
Author(s) -
Steiner Juergen M.,
Berghöfer Juergen,
Yusa Fumie,
Pompe Johannes A.,
Klösgen Ralf B.,
Löffelhardt Wolfgang
Publication year - 2005
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2004.04533.x
Subject(s) - thylakoid , plastid , chloroplast , protein targeting , twin arginine translocation pathway , phycobilisome , biology , phycobiliprotein , cyanobacteria , organelle , microbiology and biotechnology , cytosol , transport protein , botany , biochemistry , membrane , membrane protein , gene , genetics , bacteria , enzyme
Higher plant chloroplasts possess at least four different pathways for protein translocation across and protein integration into the thylakoid membranes. It is of interest with respect to plastid evolution, which pathways have been retained as a relic from the cyanobacterial ancestor (‘conservative sorting’), which ones have been kept but modified, and which ones were developed at the organelle stage, i.e. are eukaryotic achievements as (largely) the Toc and Tic translocons for envelope import of cytosolic precursor proteins. In the absence of data on cyanobacterial protein translocation, the cyanelles of the glaucocystophyte alga Cyanophora paradoxa for which in vitro systems for protein import and intraorganellar sorting were elaborated can serve as a model: the cyanelles are surrounded by a peptidoglycan wall, their thylakoids are covered with phycobilisomes and the composition of their oxygen‐evolving complex is another feature shared with cyanobacteria. We demonstrate the operation of the Sec and Tat pathways in cyanelles and show for the first time in vitro protein import across cyanobacteria‐like thylakoid membranes and protease protection of the mature protein.