agar and dimyristoylphosphatidic-acid

This is the first report describing the cloning and characterization of sterol carrier protein-2 (SCP-2) from plants. Arabidopsis thaliana SCP-2 (AtSCP-2) consists of 123 amino acids with a molecular mass of 13.6 kDa. AtSCP-2 shows 35% identity and 56% similarity to the human SCP-2-like domain present in the human D-bifunctional protein (DBP) and 30% identity and 54% similarity to the human SCP-2 encoded by SCP-X. The presented structural models of apo-AtSCP-2 and the ligand-bound conformation of AtSCP-2 reveal remarkable similarity with two of the structurally known SCP-2s, the SCP-2-like domain of human DBP and the rabbit SCP-2, correspondingly. The AtSCP-2 models in both forms have a similar hydrophobic ligand-binding tunnel, which is extremely suitable for lipid binding. AtSCP-2 showed in vitro transfer activity of BODIPY-phosphatidylcholine (BODIPY-PC) from donor membranes to acceptor membranes. The transfer of BODIPY-PC was almost completely inhibited after addition of 1-palmitoyl 2-oleoyl phosphatidylcholine or ergosterol. Dimyristoyl phosphatidic acid, stigmasterol, steryl glucoside, and cholesterol showed a moderate to marginal ability to lower the BODIPY-PC transfer rate, and the single chain palmitic acid and stearoyl-coenzyme A did not affect transfer at all. Expression analysis showed that AtSCP-2 mRNA is accumulating in most plant tissues. Plasmids carrying fusion genes between green fluorescent protein and AtSCP-2 were transformed with particle bombardment to onion epidermal cells. The results from analyzing the transformants indicate that AtSCP-2 is localized to peroxisomes.

Topics: Agar; Amino Acid Sequence; Animals; Antigens, Plant; Arabidopsis; Binding, Competitive; Boron Compounds; Carrier Proteins; Cholesterol; Cloning, Molecular; Computational Biology; Electrophoresis, Polyacrylamide Gel; Ergosterol; Escherichia coli; Fluorescence Resonance Energy Transfer; Fluorescent Dyes; Glucosides; Glutathione Transferase; Glycerophospholipids; Green Fluorescent Proteins; Humans; Lipids; Models, Chemical; Models, Molecular; Molecular Sequence Data; Onions; Palmitic Acid; Peroxisomes; Phosphatidylcholines; Phylogeny; Plant Proteins; Plasmids; Protein Conformation; Protein Structure, Secondary; Protein Structure, Tertiary; Rabbits; Recombinant Proteins; Reverse Transcriptase Polymerase Chain Reaction; RNA; Sequence Homology, Amino Acid; Sterols; Stigmasterol; Time Factors