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Substrate Induced Movement of the Metal Cofactor between Active and Resting State.
Stefan R Marsden1, Hein J Wijma2, Michael K F Mohr1
1Biokatalyse, Afdeling Biotechnologie, Technische Universiteit Delft, van der Maasweg 9, 2629HZ, Delft, The Netherlands.
Angewandte Chemie (International Ed. in English)
|October 10, 2022
Summary
Metalloenzyme regulation typically involves protein changes. However, hydroxyketoacid aldolase uses metal cofactor movement between two states, enabling substrate binding and catalysis without altering its protein structure.
Area of Science:
- Biochemistry
- Structural Biology
- Enzymology
Background:
- Enzyme activity regulation is crucial for life.
- Metalloenzymes often require extensive protein scaffold rearrangements for allosteric regulation of metal cofactors.
Purpose of the Study:
- To investigate the regulatory mechanism of hydroxyketoacid aldolase (SwHKA) from Sphingomonas wittichii RW1.
- To elucidate the role of metal cofactor dynamics in enzyme activity.
Main Methods:
- Structural analysis of SwHKA.
- Investigation of metal cofactor coordination spheres and their relation to enzyme states.
Main Results:
- SwHKA exhibits metal cofactor movement between two distinct coordination spheres (M2+R and M2+A) without protein scaffold rearrangement.
- The resting state (M2+R) sequesters the metal at the dimer interface, preventing substrate binding.
- The active state (M2+A), located 2.4 Å away, facilitates bidentate ketoacid substrate coordination, driving the transition from M2+R to M2+A.
Conclusions:
- SwHKA employs a novel allosteric regulation mechanism based on metal cofactor mobility.
- This metal-based regulation, potentially widespread, may be overlooked in structural studies due to low-occupancy states.
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