A chloroplast membrane protein LTO1/AtVKOR involving in redox regulation and ROS homeostasis

Abstract

The role of LTO1/ At VKOR-DsbA in ROS homeostasis and in redox regulation of cysteine-containing proteins in chloroplast was studied in lto1 - 2 mutant, and a potential target of LTO1 was captured. A chloroplast membrane protein LTO1/AtVKOR-DsbA encoded by the gene At4g35760 was recently found to be an oxidoreductase and involved in assembly of PSII. Here, the growth of a mutant lto1-2 line of Arabidopsis was found to be severely stunted and transgenic complementation ultimately demonstrated the phenotype changes were due to this gene. A proteomic experiment identified 23 proteins presenting a differential abundance in lto1-2 compared with wild-type plants, including components in PSII and proteins scavenging active oxygen. Three scavengers of active oxygen, L-ascorbate peroxidase 1, peroxisomal catalase 2, dehydroascorbate reductase 1, are reduced in lto1-2 plants, corresponding to high levels of accumulation of reactive oxygen species (ROS). The photosynthetic activities of PSII and the quantity of core protein D1 decreased significantly in lto1-2. Further investigation showed the synthesis of D1 was not affected in mutants both at transcription and translation levels. The soluble DsbA-like domain of LTO1 was found to have reduction, oxidation and isomerization activities, and could promote the formation of disulfide bonds in a lumenal protein, FKBP13. A potential target of LTO1 was captured which was involving in chlorophyll degradation and photooxidative stress response. Experimental results imply that LTO1 plays important roles in redox regulation, ROS homeostasis and maintenance of PSII.

Reactive Oxygen Species and Photosynthesis

“…A chloroplast membrane protein LTO1/AtVKOR-DsbA is involved in ROS homeostasis and in redox regulation of cysteine-containing proteins in chloroplast (Lu et al, 2013). In lto1-2 plants the activity of APX, CAT and DHAR is reduced simultaneous with ROS accumulation.…”

“…In lto1-2 plants the activity of APX, CAT and DHAR is reduced simultaneous with ROS accumulation. The soluble DsbAlike domain of LTO1 has reduction, oxidation and isomerization activities, and its potential target is involved in chlorophyll degradation and photooxidative stress response (Lu et al, 2013). Intracellular Ca 21 fluxes and signaling molecules, such as phosphoinositides and jasmonic acid (JA), respond to oxidative stress and could serve as regulatory cross-talk between pathways (Knight and Knight, 2001).…”

Understanding the roles of the thylakoid lumen in photosynthesis regulation

“…VDE contains disulfides that are vital for its activity in NPQ (Hall et al, 2010). The substrate-binding/PPIase activity of FKBP13 is controlled by two disulfide bridges that can be reduced and oxidized in vitro by TRX (Gopalan et al, 2004, 2006) and LTO1 (Lu et al, 2013), respectively. This suggests that the interaction between FKBP13 and the Rieske iron–sulfur protein may be linked to redox state of the thylakoid (Gollan et al, 2011).…”

De novo Comparative Transcriptome Analysis of Acremonium chrysogenum: High-Yield and Wild-Type Strains of Cephalosporin C Producer

“…The formation of ROS involves receiving a single electron from oxygen by important enzymes such as cytochrome C oxidase. Loss of cytochrome C oxidase promotes RAS-dependent ROS production [48], [49], and peroxisomal membrane protein production [50]. In HY, the transcription level of a probable cytochrome C oxidase and a probable peroxisomal membrane protein are lower than that in WT strain.…”