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Multifunctional enzymes and evolution of biosynthetic pathways: retro-evolution by jumps
1Department of Biophysics, Bose Institute, Calcutta, India. siddarth@boseinst.ernet.in
Proteins
|December 3, 1999
Summary
Biosynthetic pathways likely evolved through enzyme recruitment, not step-by-step changes. This study proposes evolution occurred via enzyme "jumps" or single "leaps" from multifunctional enzymes, supported by enzyme homology.
Area of Science:
- Biochemistry and Evolutionary Biology
- Molecular Evolution
- Enzymology
Background:
- Biosynthetic pathway evolution is traditionally viewed as a stepwise recruitment of enzymes.
- Previous models suggested retro-evolution occurred in response to metabolite availability.
- The instability of metabolic intermediates challenges stepwise retro-evolutionary models.
Purpose of the Study:
- To propose an alternative model for the evolution of biosynthetic pathways.
- To challenge the stepwise retro-evolution hypothesis.
- To investigate the role of multifunctional enzymes and gene duplication in pathway evolution.
Main Methods:
- Theoretical argumentation based on chemical stability of intermediates.
- Speculation on the role of primordial multienzymes.
- Examination of sequence and structural homologies among extant pathway enzymes.
Main Results:
- Retro-evolution via small steps is unlikely due to intermediate instability.
- Pathway evolution likely occurred through 'jumps' involving multifunctional enzymes.
- A single 'leap' from a primordial multienzyme is a possible evolutionary route.
Conclusions:
- Biosynthetic pathways may have evolved rapidly via recruitment of enzymes catalyzing multiple steps.
- Gene duplication and subsequent enzyme refinement led to current pathways.
- Enzyme homology supports a common ancestry for enzymes within a pathway.