Structure and function of normal and transformed murine acyl-CoA binding proteins

Area of Science:

• Biochemistry
• Molecular Biology
• Cell Biology

Background:

• Acyl-CoA binding protein (ACBP) is abundant in tumorigenic cells, but its specific role in malignant cells and phospholipid synthesis is unclear.
• The molecular basis for elevated ACBP levels in cancer and its precise function in microsomal phospholipid metabolism require elucidation.

Purpose of the Study:

• To investigate whether Acyl-CoA binding protein (ACBP) from tumorigenic cells differs structurally from native ACBP.
• To characterize the ligand binding properties and functional role of mouse ACBP in microsomal phospholipid synthesis.
• To compare the effects of mouse ACBP with rat ACBP on microsomal phospholipid metabolism.

Main Methods:

• Purification of ACBP from LM cells (tumorigenic mouse fibroblasts) and structural analysis using mass spectrometry.
• Fluorescent binding assays to determine the affinity and stoichiometry of ACBP-ligand interactions.
• Enzymatic assays measuring microsomal phosphatidic acid formation and phospholipid acyl chain remodeling using specific Acyl-CoA substrates.

Main Results:

• ACBP from tumorigenic LM cells was structurally identical to native mouse ACBP, with no sequence variations or posttranslational modifications.
• Mouse ACBP exhibited high-affinity binding to cis-parinaroyl-CoA and significantly enhanced microsomal phosphatidic acid formation.
• ACBP inhibited phospholipid acyl chain remodeling but shifted oleoyl-CoA incorporation towards phosphatidic acid biosynthesis, with subtle species-specific differences between mouse and rat ACBP.

Conclusions:

• ACBP from tumorigenic cells does not differ structurally from normal ACBP.
• ACBP plays a direct role in stimulating microsomal phosphatidic acid biosynthesis and influencing phospholipid acyl chain remodeling in vitro.
• Subtle amino acid differences between mouse and rat ACBP result in distinct effects on microsomal phospholipid metabolism.