Premium
The transporter Syn PAM 71 is located in the plasma membrane and thylakoids, and mediates manganese tolerance in Synechocystis PCC 6803
Author(s) -
Gandini Chiara,
Schmidt Sidsel Birkelund,
Husted Søren,
Schneider Anja,
Leister Dario
Publication year - 2017
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.14526
Subject(s) - thylakoid , photosystem ii , synechocystis , chloroplast , periplasmic space , photosynthesis , chemistry , cytoplasm , biochemistry , biology , biophysics , microbiology and biotechnology , mutant , gene , escherichia coli
Summary Manganese (Mn) is an essential constituent of photosystem II ( PSII ) and therefore indispensable for oxygenic photosynthesis. Very little is known about how Mn is transported, delivered and retained in photosynthetic cells. Recently, the thylakoid‐localized transporter PAM 71 has been linked to chloroplast Mn homeostasis in Arabidopsis thaliana . Here, we characterize the function of its homolog in Synechocystis (Syn PAM 71). We used a loss‐of‐function line ( ΔSyn PAM 71 ), wild‐type ( WT ) cells exposed to Mn stress and strains expressing a tagged variant of Syn PAM 71 to characterize the role of Syn PAM 71 in cyanobacterial Mn homeostasis. The ΔSyn PAM 71 strain displays an Mn‐sensitive phenotype with reduced levels of chlorophyll and PSI accumulation, defects in PSII photochemistry and intracellular Mn enrichment, particularly in the thylakoid membranes. These effects are attributable to Mn toxicity, as very similar symptoms were observed in WT cells exposed to excess Mn. Moreover, CyanoP, which is involved in the early steps of PSII assembly, is massively upregulated in ΔSyn PAM 71 . Syn PAM 71 was detected in both the plasma membrane and, to a lesser extent, the thylakoid membranes. Our results suggest that Syn PAM 71 is involved in the maintenance of Mn homeostasis through the export of Mn from the cytoplasm into the periplasmic and luminal compartments, where it can be stored without interfering with cytoplasmic metabolic processes.