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Human geranylgeranyl diphosphate synthase. cDNA cloning and expression
T Kuzuguchi1, Y Morita, I Sagami
1Institute for Chemical Reaction Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan.
The Journal of Biological Chemistry
|February 20, 1999
Summary
Geranylgeranyl diphosphate synthase (GGPPSase) produces GGPP, vital for protein prenylation and nuclear receptor regulation. This study characterizes human GGPPSase, revealing its enzymatic activity and distinct properties from FPPSase.
Area of Science:
- Biochemistry
- Molecular Biology
- Enzymology
Background:
- Geranylgeranyl diphosphate (GGPP) is crucial for C20-prenylated protein biosynthesis and nuclear hormone receptor regulation (LXR.RXR).
- Understanding the enzymes involved in GGPP synthesis is essential for comprehending these biological processes.
Purpose of the Study:
- To characterize the human Geranylgeranyl diphosphate synthase (GGPPSase).
- To investigate its enzymatic activity, protein properties, and relationship to other prenyltransferases.
Main Methods:
- Cloning and expression of human GGPPSase cDNA in Escherichia coli.
- Enzymatic assays to measure GGPP formation.
- Gel filtration chromatography to determine molecular weight.
- Immunological cross-reactivity studies using antibodies against bovine GGPPSase.
- Northern blot analysis to examine mRNA expression.
Main Results:
- Human GGPPSase cDNA encodes a 300-amino acid protein with 16% sequence identity to human farnesyl diphosphate synthase (FPPSase).
- Expressed GGPPSase efficiently catalyzes GGPP synthesis from FPP and isopentenyl diphosphate.
- The enzyme exists as an oligomeric molecule (~280 kDa) and is immunochemically distinct from FPPSase.
- Northern blot analysis revealed two distinct mRNA forms.
Conclusions:
- Human GGPPSase is a distinct enzyme responsible for GGPP synthesis.
- Its oligomeric nature and immunochemical properties differentiate it from FPPSase.
- The presence of two mRNA forms suggests potential isoforms or regulatory mechanisms.