title: Heterologous expression of a chloroplast outer envelope protein from Suaeda salsa confers oxidative stress tolerance and induces chloroplast aggregation in transgenic Arabidopsis plants.
abstract: Suaeda salsa is a euhalophytic plant that is tolerant to coastal seawater salinity. In this study, we cloned a cDNA encoding an 8.4 kDa chloroplast outer envelope protein (designated as SsOEP8) from S. salsa and characterized its cellular function. Steady-state transcript levels of SsOEP8 in S. salsa were up-regulated in response to oxidative stress. Consistently, ectopic expression of SsOEP8 conferred enhanced oxidative stress tolerance in transgenic Bright Yellow 2 (BY-2) cells and Arabidopsis, in which H(2) O(2)  content was reduced significantly in leaf cells. Further studies revealed that chloroplasts aggregated to the sides of mesophyll cells in transgenic Arabidopsis leaves, and this event was accompanied by inhibited expression of genes encoding proteins for chloroplast movements such as AtCHUP1, a protein involved in actin-based chloroplast positioning and movement. Moreover, organization of actin cytoskeleton was found to be altered in transgenic BY-2 cells. Together, these results suggest that SsOEP8 may play a critical role in oxidative stress tolerance by changing actin cytoskeleton-dependent chloroplast distribution, which may consequently lead to the suppressed production of reactive oxygen species (ROS) in chloroplasts. One significantly novel aspect of this study is the finding that the small chloroplast envelope protein is involved in oxidative stress tolerance.
authors: Institute of Microbiology, Chinese Academy of Sciences, Beijing, China. wangfang@genetics.ac.cn
authors: Fang
authors: F
authors: Wang
authors: Chun-Lin
authors: CL
authors: Yang
authors: Li-Li
authors: LL
authors: Wang
authors: Nai-Qin
authors: NQ
authors: Zhong
authors: Xiao-Min
authors: XM
authors: Wu
authors: Li-Bo
authors: LB
authors: Han
authors: Gui-Xian
authors: GX
authors: Xia
mesh_terms: D000199:Actins / Q000378:metabolism; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000502:physiology*; D001483:Base Sequence; D002478:Cells, Cultured; D019663:Chenopodiaceae / Q000235:genetics* / Q000378:metabolism; D060365:Chloroplast Proteins / Q000235:genetics / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism*; D003001:Cloning, Molecular; D003599:Cytoskeleton / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D006861:Hydrogen Peroxide / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D018384:Oxidative Stress; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000502:physiology
chemical_list: D000199:Actins; D060365:Chloroplast Proteins; D018076:DNA, Complementary; D008565:Membrane Proteins; D010940:Plant Proteins; D006861:Hydrogen Peroxide