The catalytic power of magnesium chelatase: a benchmark for the AAA+ATP ases
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In the first committed reaction of chlorophyll biosynthesis, magnesium chelatase couples ATP hydrolysis to the thermodynamically unfavorable Mg 2+ insertion into protoporphyrin IX (ΔG°′ of circa 25–33 kJ·mol−1). We explored the thermodynamic constraints on magnesium chelatase and demonstrate the effect of nucleotide hydrolysis on both the reaction kinetics and thermodynamics. The enzyme produces a significant rate enhancement (kcat/kuncat of 400 × 10 6 m) and a catalytic rate enhancement, , of 30 × 10 15 m−1, increasing to 300 × 10 15 m−1 with the activator protein Gun4. This is the first demonstration of the thermodynamic benefit of ATP hydrolysis in the AAA+ family.
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The reaction catalyzed by Mg2+ chelatase is unfavorable (Keq ∼ 10-6) and is coupled to ATP hydrolysis.
“The reaction catalyzed by Mg2+ chelatase is unfavorable (Keq ∼ 10–6) and is coupled to ATP hydrolysis.84”
From Metals in Motion: Understanding Labile Metal Pools in Bacteria (2025) · cites this paper as [84]
Once synthesized, chlorophyll-Mg complexes are stable, with spontaneous Mg2+ loss occurring with a half-time of ∼6 h, and are therefore no longer part of the labile pool.
“Once synthesized, chlorophyll-Mg complexes are stable (spontaneous Mg2+ loss occurs with a half-time of ∼6 h),84 and therefore no longer part of the labile pool.”
From Metals in Motion: Understanding Labile Metal Pools in Bacteria (2025) · cites this paper as [84]
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Research works printed but not linked: 26
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Metals in Motion: Understanding Labile Metal Pools in Bacteria
Helmann, J. D. (2025) · Biochemistry · doi:10.1021/acs.biochem.4c00726 · Cited by 49 · see citing works
- Authors
- Adams, N. B. P., Brindley, A. A., Hunter, C. N., & Reid, J. D.
- Affiliations
- University of Sheffield (GB)
- Corresponding author
- Reid, James D.
- Venue
- FEBS Letters
- Publisher
- Wiley
- Published
- 2016-06
- Volume
- 590
- Issue
- 12
- Pages
- 1687-1693
- ISSN
- 0014-5793 (ISSN-L)
- 1873-3468
- PMC
- PMC4982103
- OpenAlex
- W2351233780
- Cited by
- 15
- References
- 0
- Citations by year
- 2026: 2 · 2025: 1 · 2024: 1 · 2023: 3 · 2021: 1 · 2020: 3 · 2019: 4
- FWCI
- 0.57
- Type
- journal article
- Language
- en
- Open access
- hybrid
- doi.org
- Licence
- Locations
- FEBS Letters (publishedVersion, cc-by)
- Europe PMC (PubMed Central) (publishedVersion, cc-by)
- PubMed Central (publishedVersion, cc-by)
- PubMed (publishedVersion)
- White Rose Research Online (University of Leeds, The University of Sheffield, University of York) (acceptedVersion)
- Funders
- Biotechnology and Biological Sciences Research Council (BB/G021546/1, BB/M000265/1)
- Topics
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Photosynthetic Processes and Mechanisms
- Physical Sciences › Materials Science › Materials Chemistry › Porphyrin and Phthalocyanine Chemistry
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Porphyrin Metabolism and Disorders
- Keywords
- magnesium chelatase, AAA+ ATPase, chlorophyll biosynthesis, protoporphyrin IX, ATP hydrolysis, catalytic rate enhancement, reaction kinetics
- MeSH terms
- Adenosine Triphosphatases, Adenosine Triphosphate, Catalysis, Lyases, Magnesium, Protoporphyrins, Synechocystis
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