Goose fatty acid synthetase mRNA

Area of Science:

• Biochemistry
• Molecular Biology
• Enzymology

Background:

• Animal fatty acid synthetase is a large, multienzyme protein composed of identical subunits.
• Each subunit possesses multiple catalytic domains for fatty acid synthesis.
• The precise genetic and translational mechanism for synthesizing these large subunits was not fully understood.

Purpose of the Study:

• To investigate the molecular nature of fatty acid synthetase (FAS) messenger RNA (mRNA).
• To determine if the FAS subunit is synthesized as a single polypeptide chain from a contiguous mRNA.
• To confirm the multifunctional nature of the FAS enzyme.

Main Methods:

• Isolation and translation of total poly(A+) RNA from goose uropygial gland in a cell-free rabbit reticulocyte system.
• Characterization of translation products using molecular weight determination and antibody binding assays.
• Fractionation of poly(A+) RNA via sucrose gradient centrifugation and analysis of mRNA species using gel electrophoresis and glyoxylation.

Main Results:

• In vitro translation produced a polypeptide identical in molecular weight to native fatty acid synthetase subunits.
• Antibodies against synthetase specifically recognized the in vitro synthesized polypeptide.
• Analysis revealed a very large mRNA species (35 S, molecular weight 2.95 X 10^6) capable of coding for the 250,000 molecular weight synthetase subunit.

Conclusions:

• The fatty acid synthetase subunit is synthesized as a single, large polypeptide chain.
• A single, contiguous mRNA molecule encodes the entire multifunctional fatty acid synthetase subunit.
• These findings support the concept of large, multifunctional proteins arising from single mRNA transcripts.