CHAPERONIN 20 mediates iron superoxide dismutase (FeSOD) activity independent of its co‐chaperonin role in Arabidopsis chloroplasts. Issue 1 (11th October 2012)

• Record Type: Journal Article
• Authors: Kuo, W. Y.; Huang, C. H.; Liu, A. C.; Cheng, C. P.; Li, S. H.; Chang, W. C.; Weiss, C.; Azem, A.; Jinn, T. L.
• Is Part Of: New phytologist. Volume 197:Issue 1(2013)
• Page Start: 99
• Page End: 110
• Publication Date: 2012-10-11
• Subjects: Botany -- Periodicals; 580
• DOI: 10.1111/j.1469-8137.2012.04369.x
• Languages: English
• ISSNs: 0028-646X

Abstract

<abstract abstract-type="main" xml:lang="en" id="nph4369-abs-0001"> <title>Summary</title> <p> <list id="nph4369-list-0001" list-type="bullet"> <list-item> <p>Iron superoxide dismutases (FeSODs; FSDs) are primary antioxidant enzymes in <italic>Arabidopsis thaliana</italic> chloroplasts. The stromal FSD1 conferred the only detectable FeSOD activity, whereas the thylakoid membrane‐ and nucleoid‐co‐localized FSD2 and FSD3 double mutant showed arrested chloroplast development.</p> </list-item> <list-item> <p>FeSOD requires cofactor Fe for its activity, but its mechanism of activation is unclear. We used reversed‐phase high‐performance liquid chromatography (HPLC), gel filtration chromatography, LC‐MS/MS, protoplast transient expression and virus‐induced gene silencing (VIGS) analyses to identify and characterize a factor involved in FeSOD activation.</p> </list-item> <list-item> <p>We identified the chloroplast‐localized co‐chaperonin CHAPERONIN 20 (CPN20) as a mediator of FeSOD activation by direct interaction. The relationship between CPN20 and FeSOD was confirmed by <italic>in vitro</italic> experiments showing that CPN20 alone could enhance FSD1, FSD2 and FSD3 activity. The <italic>in vivo</italic> results showed that <italic>CPN20‐</italic>overexpressing mutants and mutants with defective co‐chaperonin activity increased FSD1 activity, without changing the chaperonin CPN60 protein level, and VIGS‐induced downregulation of <italic>CPN20</italic> also led to decreased FeSOD activity.</p> </list-item> <list-item> <p>Our findings reveal that CPN20 can mediate FeSOD activation in chloroplasts, a role independent of its known function in the chaperonin system.</p> </list-item> </list> </p> </abstract>