Overexpression of Arabidopsis acyl-CoA binding protein ACBP3 promotes starvation-induced and age-dependent leaf senescence.
In Arabidopsis thaliana, a family of six genes (ACBP1 to ACBP6) encodes acyl-CoA binding proteins (ACBPs). Investigations on ACBP3 reported here show its upregulation upon dark treatment and in senescing rosettes. Transgenic Arabidopsis overexpressing ACBP3 (ACBP3-OEs) displayed accelerated leaf senescence, whereas an acbp3 T-DNA insertional mutant and ACBP3 RNA interference transgenic Arabidopsis lines were delayed in dark-induced leaf senescence. Acyl-CoA and lipid profiling revealed that the overexpression of ACBP3 led to an increase in acyl-CoA and phosphatidylethanolamine (PE) levels, whereas ACBP3 downregulation reduced PE content. Moreover, significant losses in phosphatidylcholine (PC) and phosphatidylinositol, and gains in phosphatidic acid (PA), lysophospholipids, and oxylipin-containing galactolipids (arabidopsides) were evident in 3-week-old dark-treated and 6-week-old premature senescing ACBP3-OEs. Such accumulation of PA and arabidopsides (A, B, D, E, and G) resulting from lipid peroxidation in ACBP3-OEs likely promoted leaf senescence. The N-terminal signal sequence/transmembrane domain in ACBP3 was shown to be essential in ACBP3-green fluorescent protein targeting and in promoting senescence. Observations that recombinant ACBP3 binds PC, PE, and unsaturated acyl-CoAs in vitro and that ACBP3 overexpression enhances degradation of the autophagy (ATG)-related protein ATG8 and disrupts autophagosome formation suggest a role for ACBP3 as a phospholipid binding protein involved in the regulation of leaf senescence by modulating membrane phospholipid metabolism and ATG8 stability in Arabidopsis. Accelerated senescence in ACBP3-OEs is dependent on salicylic acid but not jasmonic acid signaling.
Xiao
Shi
S
School of Biological Sciences, University of Hong Kong, Pokfulam, Hong Kong, China.
Gao
Wei
W
Chen
Qin-Fang
QF
Chan
Suk-Wah
SW
Zheng
Shu-Xiao
SX
Ma
Jinyu
J
Wang
Mingfu
M
Welti
Ruth
R
Chye
Mee-Len
ML
D000214:Acyl Coenzyme A / Q000378:metabolism; D017360:Arabidopsis / Q000166:cytology* / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D016922:Cellular Senescence / Q000187:drug effects / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D003624:Darkness; D015536:Down-Regulation / Q000187:drug effects; D004952:Esters / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008563:Membrane Lipids / Q000378:metabolism; D016254:Mutagenesis, Insertional / Q000235:genetics; D010084:Oxidation-Reduction / Q000187:drug effects; D010588:Phagosomes / Q000187:drug effects / Q000378:metabolism; D010641:Phenotype; D010713:Phosphatidylcholines / Q000378:metabolism; D010714:Phosphatidylethanolamines / Q000378:metabolism; D018515:Plant Leaves / Q000166:cytology* / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D030821:Plants, Genetically Modified; D011485:Protein Binding / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D034622:RNA Interference / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020156:Salicylic Acid / Q000494:pharmacology
C513212:ACBP3 protein, Arabidopsis; D000214:Acyl Coenzyme A; D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D004269:DNA, Bacterial; D004952:Esters; D008563:Membrane Lipids; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; C036483:T-DNA; D049452:Green Fluorescent Proteins; C483858:phosphatidylethanolamine; D020156:Salicylic Acid