Peroxiredoxin Q of Arabidopsis thaliana is attached to the thylakoids and functions in context of photosynthesis.
Peroxiredoxin Q (Prx Q) is one out of 10 peroxiredoxins encoded in the genome of Arabidopsis thaliana, and one out of four that are targeted to plastids. Peroxiredoxin Q functions as a monomeric protein and represents about 0.3% of chloroplast proteins. It attaches to the thylakoid membrane and is detected in preparations enriched in photosystem II complexes. Peroxiredoxin Q decomposes peroxides using thioredoxin as an electron donor with a substrate preference of H(2)O(2) > cumene hydroperoxide >> butyl hydroperoxide >> linoleoyl hydroperoxide and insignificant affinity towards complex phospholipid hydroperoxide. Plants with decreased levels of Prx Q did not have an apparently different phenotype from wildtype at the plant level. However, similar to antisense 2-cysteine (2-Cys) Prx plants [Baier, M. et al. (2000)Plant Physiol., 124, 823-832], Prx Q-deficient plants had a decreased sensitivity to oxidants in a leaf slice test as indicated by chlorophyll a fluorescence measurements. Increased fluorescence ratios of photosystem II to I at 77 K and modified transcript levels of plastid- and nuclear-encoded proteins show that regulatory mechanisms are at work to compensate for the lack of Prx Q. Apparently Prx Q attaches to photosystem II and has a specific function distinct from 2-Cys peroxiredoxin in protecting photosynthesis. Its absence causes metabolic changes that are sensed and trigger appropriate compensatory responses.
Lamkemeyer
Petra
P
Biochemistry and Physiology of Plants, Bielefeld University, 33501 Bielefeld, Germany.
Laxa
Miriam
M
Collin
Valérie
V
Li
Wenxue
W
Finkemeier
Iris
I
Schöttler
Mark A
MA
Holtkamp
Volker
V
Tognetti
Vanesa B
VB
Issakidis-Bourguet
Emmanuelle
E
Kandlbinder
Andrea
A
Weis
Engelbert
E
Miginiac-Maslow
Myroslawa
M
Dietz
Karl-Josef
KJ
D017360:Arabidopsis / Q000201:enzymology* / Q000502:physiology / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D004269:DNA, Bacterial / Q000235:genetics; D005453:Fluorescence; D007425:Intracellular Membranes / Q000201:enzymology; D016254:Mutagenesis, Insertional; D010084:Oxidation-Reduction; D010544:Peroxidases / Q000032:analysis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D054464:Peroxiredoxins; D010641:Phenotype; D010788:Photosynthesis / Q000502:physiology*; D045332:Photosystem II Protein Complex / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism / Q000648:ultrastructure; D018087:Plastids / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020524:Thylakoids / Q000201:enzymology*
D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; D045332:Photosystem II Protein Complex; D012333:RNA, Messenger; C036483:T-DNA; D010544:Peroxidases; D054464:Peroxiredoxins; C510753:peroxiredoxin Q, Arabidopsis