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Updated: Mar 21, 2026
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Concanavalin A-Based Sedimentation Assay to Measure Substrate Binding of Glucan Phosphatases
Published on: December 23, 2022
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Unique carbohydrate binding platforms employed by the glucan phosphatases.
Shane Emanuelle1, M Kathryn Brewer1, David A Meekins2
1Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, Lexington, Kentucky 40536 USA.
Cellular and Molecular Life Sciences : CMLS
|May 6, 2016
Summary
Glucan phosphatases in animals and plants dephosphorylate glycogen and starch, respectively. Despite conserved enzymatic function, these enzymes utilize distinct binding mechanisms for their respective substrates, highlighting evolutionary divergence.
Area of Science:
- Biochemistry
- Enzymology
- Molecular Biology
Background:
- Glucan phosphatases are enzymes conserved across animals and plants, responsible for dephosphorylating glycogen and starch.
- The founding member, laforin, possesses a carbohydrate-binding module 20 (CBM20) and a dual-specificity phosphatase (DSP) domain.
- Plants have two glucan phosphatases: Starch EXcess4 (SEX4) and Like Sex Four2 (LSF2), both containing DSP domains.
Purpose of the Study:
- To elucidate the biological roles of glucan phosphatases in glycogen and starch metabolism.
- To compare and contrast the distinct mechanisms employed by these enzymes for substrate binding and dephosphorylation.
- To analyze the structural and functional differences between animal (laforin) and plant (SEX4, LSF2) glucan phosphatases.
Main Methods:
- Comparative analysis of enzyme structures and domains (CBM20, DSP, CBM45).
- Investigation of substrate binding sites and mechanisms in SEX4 and LSF2.
- Examination of laforin's quaternary structure and cooperative binding properties.
Main Results:
- SEX4 utilizes an integrated DSP-CBM glucan-binding platform for starch interaction.
- LSF2 lacks a CBM but employs two surface binding sites for starch dephosphorylation.
- Laforin functions as a dimer, utilizing a tetramodular architecture and cooperativity for glycogen binding.
Conclusions:
- Glucan phosphatases exhibit functional conservation but distinct substrate-binding mechanisms.
- Plant glucan phosphatases (SEX4, LSF2) have evolved unique strategies for starch metabolism.
- Understanding these diverse mechanisms provides insights into the regulation of carbohydrate metabolism.
Keywords:
Dual specificity phosphataseGlucan interactionsGlucan phosphataseGlycogenReversible phosphorylationStarchMore Related Videos
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