Article

Arabidopsis acyl-CoA-binding proteins ACBP4 and ACBP5 are subcellularly localized to the cytosol and ACBP4 depletion affects membrane lipid composition.

School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
Plant Molecular Biology (impact factor: 4.15). 10/2008; 68(6):571-83. DOI:10.1007/s11103-008-9392-7 pp.571-83
Source: PubMed

ABSTRACT In Arabidopsis thaliana, acyl-CoA-binding proteins (ACBPs) are encoded by six genes, and they display varying affinities for acyl-CoA esters. Recombinant ACBP4 and ACBP5 have been shown to bind oleoyl-CoA esters in vitro. In this study, the subcellular localizations of ACBP4 and ACBP5 were determined by biochemical fractionation followed by western blot analyses using anti-ACBP4 and anti-ACBP5 antibodies and immuno-electron microscopy. Confocal microscopy of autofluorescence-tagged ACBP4 and ACBP5, expressed transiently in onion epidermal cells and in transgenic Arabidopsis, confirmed their expression in the cytosol. Taken together, ACBP4 and ACBP5 are available in the cytosol to bind and transfer cytosolic oleoyl-CoA esters. Lipid profile analysis further revealed that an acbp4 knockout mutant showed decreases in membrane lipids (digalactosyldiacylglycerol, monogalactosyldiacylglycerol, phosphatidylcholine, phosphatidylethanolamine and phosphatidylinositol) while acbp4-complemented lines attained levels similar to wild type, suggesting that ACBP4 plays a role in the biosynthesis of membrane lipids including galactolipids and phospholipids.

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    Article: New roles for acyl-CoA-binding proteins (ACBPs) in plant development, stress responses and lipid metabolism.
    Shi Xiao, Mee-Len Chye
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    ABSTRACT: ACBPs are implicated in acyl-CoA trafficking in many eukaryotes and some prokaryotes. Six genes encode proteins designated as AtACBP1-AtACBP6 in the Arabidopsis thaliana ACBP family. These ACBPs are conserved in the acyl-CoA-binding domain, but vary in size from 92 amino acids (10.4 kDa) to 668 amino acids (73.1 kDa), and are subcellularly localised to different compartments in plant cells. Results from in vitro binding assays show that their corresponding recombinant proteins exhibit differential binding affinities to acyl-CoA esters and phospholipids, implying that these ACBPs may have non-redundant biological functions in vivo. By using knockout/downregulated and overexpression lines of Arabidopsis ACBPs, recent investigations have revealed that in addition to their proposed roles in phospholipid metabolism, these ACBPs can influence plant development including early embryogenesis and leaf senescence, as well as plant stress responses including heavy metal resistance, oxidative stress, freezing tolerance and pathogen resistance. In this review, recent progress on the biochemical and functional analyses of Arabidopsis ACBPs, their links to metabolic/signalling pathways, and their potential applications in development of stress tolerance are discussed.
    Progress in lipid research 12/2010; 50(2):141-51. · 10.67 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

Keywords

acbp4 knockout mutant
 
acbp4-complemented lines attained levels
 
anti-ACBP4
 
anti-ACBP5 antibodies
 
Arabidopsis thaliana
 
autofluorescence-tagged ACBP4
 
bind oleoyl-CoA esters
 
biochemical fractionation
 
Confocal microscopy
 
Lipid profile analysis
 
membrane lipids
 
monogalactosyldiacylglycerol
 
onion epidermal cells
 
Recombinant ACBP4
 
subcellular localizations
 
transfer cytosolic oleoyl-CoA esters
 
transgenic Arabidopsis
 
vitro
 
western blot analyses
 
wild type
 

Shi Xiao