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Is there methylmalonyl CoA mutase in Aspergillus nidulans?
F D Ledley1, A M Crane, K T Klish
1Howard Hughes Medical Institute, Department of Cell Biology, Baylor College of Medicine, Houston, TX 77030.
Biochemical and Biophysical Research Communications
|June 28, 1991
Summary
The methylmalonyl CoA mutase enzyme is absent in Aspergillus nidulans, challenging prior assumptions about propionate metabolism in this fungus. This finding suggests separate evolutionary paths for this metabolic pathway in eukaryotes and animals.
Area of Science:
- Biochemistry
- Molecular Biology
- Mycology
Background:
- Methylmalonyl CoA mutase, reliant on adenosylcobalamin, is crucial for converting methylmalonyl CoA to succinyl CoA in most animals and prokaryotes.
- Previous assumptions suggested propionate metabolism in Aspergillus nidulans proceeds via propionyl CoA and methylmalonyl CoA to the TCA cycle.
Purpose of the Study:
- To investigate the presence and activity of methylmalonyl CoA mutase in Aspergillus nidulans.
- To clarify the metabolic fate of propionate in Aspergillus nidulans.
Main Methods:
- Enzyme activity assays were performed in vitro.
- Growth studies were conducted using methylmalonate as the sole carbon source.
Main Results:
- No detectable methylmalonyl CoA mutase activity was observed in Aspergillus nidulans.
- Aspergillus nidulans failed to metabolize methylmalonate or grow on media with methylmalonate as the sole carbon source.
Conclusions:
- The enzyme methylmalonyl CoA mutase is absent in Aspergillus nidulans.
- Propionate is likely not metabolized through the methylmalonyl CoA pathway in this organism.
- This supports the hypothesis of distinct evolutionary trajectories for this metabolic pathway in animals and lower eukaryotes, stemming from different mitochondrial endosymbiotic origins.