SsTypA1, a chloroplast-specific TypA/BipA-type GTPase from the halophytic plant Suaeda salsa, plays a role in oxidative stress tolerance.
Suaeda salsa is a leaf-succulent euhalophytic plant capable of surviving under seawater salinity. Here, we report the isolation and functional analysis of a novel Suaeda gene (designated as SsTypA1) encoding a member of the TypA/BipA GTPase gene family. The steady-state transcript level of SsTypA1 in S. salsa was up-regulated in response to various external stressors. Expression of SsTypA1 was restricted to the epidermal layers of the leaf and stem in S. salsa, and SsTypA1-green fluorescence protein (GFP) fusion proteins were targeted to the chloroplasts of tobacco leaves. Ectopic over-expression of SsTypA1 rendered the transgenic tobacco plants with significantly increased tolerance to oxidative stress, and this was accompanied by a reduction in H(2)O(2) content. Enzymatic and Western blot analyses revealed that the activity and amount of the thylakoid-bound NAD(P)H dehydrogenase (NDH) complex in the chloroplasts of leaf cells were enhanced. Additionally, an in vitro assay demonstrated that SsTypA1 bound to GTP and possessed GTPase activity that was stimulated by the presence of chloroplast 70S ribosomes. Together, these results suggest that SsTypA1 may play a critical role in the development of oxidative stress tolerance, perhaps as a translational regulator of the stress-responsive proteins involved in reactive oxygen species (ROS) suppression in chloroplast.
Wang
Fang
F
National Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences; National Center for Plant Gene Research, Beijing 100101, China.
Zhong
Nai-Qin
NQ
Gao
Peng
P
Wang
Gui-Ling
GL
Wang
Hai-Yun
HY
Xia
Gui-Xian
GX
D000222:Adaptation, Physiological; D001483:Base Sequence; D015152:Blotting, Northern; D019663:Chenopodiaceae / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D002736:Chloroplasts / Q000201:enzymology*; D003001:Cloning, Molecular; D017931:DNA Primers; D018076:DNA, Complementary; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000378:metabolism*; D017343:Genes, Plant; D049452:Green Fluorescent Proteins / Q000378:metabolism; D017403:In Situ Hybridization; D008855:Microscopy, Electron, Scanning; D018384:Oxidative Stress; D010802:Phylogeny; D017382:Reactive Oxygen Species; D020133:Reverse Transcriptase Polymerase Chain Reaction
D017931:DNA Primers; D018076:DNA, Complementary; D017382:Reactive Oxygen Species; D049452:Green Fluorescent Proteins; D020558:GTP Phosphohydrolases