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Updated: Jul 6, 2026

Analysis of Protein Import into Chloroplasts Isolated from Stressed Plants
Published on: November 1, 2016
Three thioredoxin targets in the inner envelope membrane of chloroplasts function in protein import and chlorophyll
Sandra Bartsch1, Julie Monnet, Kristina Selbach
1Lehrstuhl für Pflanzenphysiologie, Universität Bayreuth, Universitätsstrasse 30, D-95447 Bayreuth, Germany.
Abstract:
Thioredoxins (Trxs) are ubiquitous small proteins with a redox-active disulfide bridge. In their reduced form, they constitute very efficient protein disulfide oxidoreductases. In chloroplasts, two types of Trxs (f and m) coexist and play central roles in the regulation of the Calvin cycle and other processes. Here, we identified a class of Trx targets in the inner plastid envelope membrane of chloroplasts that share a CxxC motif approximately 73 aa from their carboxyl-terminal end. Members of this group belong to a superfamily of Rieske iron-sulfur proteins involved in protein translocation and chlorophyll metabolism. These proteins include the protein translocon protein TIC55, the precursor NADPH:protochlorophyllide oxidoreductase translocon protein PTC52, which operates as protochlorophyllide a-oxygenase, and the lethal leaf spot protein LLS1, which is identical with pheophorbide a oxygenase. The role of these proteins in dark/light regulation and oxidative control by the Trx system is discussed.
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