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Chimeric flavonol sulfotransferases define a domain responsible for substrate and position specificities
L Varin1, F Marsolais, N Brisson
1Département de Biologie, Université Laval, Ste-Foy, Québec, Canada.
The Journal of Biological Chemistry
|May 26, 1995
Summary
Researchers identified a key region in flavonol sulfotransferases (STs) responsible for substrate specificity. This discovery sheds light on enzyme function and evolution in both plant and animal sulfotransferases.
Area of Science:
- Biochemistry
- Molecular Biology
- Enzymology
Background:
- Flavonol sulfotransferases (STs) are crucial enzymes involved in plant secondary metabolism.
- Two specific STs, pFST3 and pFST4', share high amino acid identity but display distinct substrate and positional specificities.
Purpose of the Study:
- To pinpoint the specific domain within flavonol STs that dictates their substrate and positional preferences.
- To investigate the evolutionary implications of this domain by comparing plant and animal STs.
Main Methods:
- Construction of chimeric flavonol ST enzymes through reciprocal DNA fragment exchange between pFST3 and pFST4'.
- Expression and enzymatic characterization of these chimeric proteins in Escherichia coli.
- Comparative analysis of amino acid sequences between plant and animal STs.
Main Results:
- Chimeric ST enzymes retained activity, albeit reduced compared to parent enzymes.
- A specific interval (amino acids 92-194 in flavonol 3-ST) was identified as the determinant for substrate and positional specificity.
- This critical interval contains a highly conserved region flanked by divergent regions, showing similarities to animal STs.
Conclusions:
- The identified interval (amino acids 92-194) is crucial for determining substrate and positional specificity in flavonol STs.
- Structural and sequence similarities suggest this interval plays a conserved role in substrate recognition and/or catalysis across diverse STs, including animal counterparts.