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Cited by 3Metalloenzymes and iron-sulfur proteinsPorphyrin Metabolism and DisordersEnzyme Structure and Function

The DOI matches its Crossref record; 60 of the 60 references it cites were found in a registry or an index.

Archaeoglobus fulgidus CbiX S is a Cobalt Chelatase Where Co(II) is Ligated by His10 and His74

Open access
Morris, Jacob A., Ayodele-Davis, Oluwamuyiwa O. E., Lavigne, Megan E., Martorelli Di Genova, Bruno, Liptak, Matthew D.·2026·Inorganic Chemistry

Published version of a preprint

Abstract

Archaeoglobus fulgidus CbiXS is a small (16 kD) class II chelatase with structural homology to the CfbA nickel chelatase required for the biosynthesis of cofactor F430. However, the biochemical function of A. fulgidus CbiXS has remained a point of confusion in the literature with assignments as either a cobalt or a nickel chelatase. In this work, we analyze the genome of A. fulgidus revealing that the organism lacks the cofactor F430 biosynthetic pathway but contains a nearly complete vitamin B12 biosynthetic pathway lacking a cobalt chelatase. Characterization of metal-free and metal-bound forms of CbiXS with electrospray ionization spectrometry (ESI-MS) indicated that CbiXS binds a divalent metal substrate using two protonatable amino acids. Additional characterization of CbiXS using UV circular dichroism spectroscopy suggest that the protein remains folded in the pH 6-8 range. Using established competitive binding assays, it was discovered that divalent metal binding by CbiXS is a notable exception to the Irving-Williams series, with Co(II) and Ni(II) binding affinities within error of one another at pH 7.0. Additional competitive binding experiments at pH 6.0 and 8.0 suggest that Co(II) and Ni(II) are ligated by amino acids with side-chain pKa values between 6.0 and 7.0. Collectively, these data lead to the assignment of CbiXS as a novel cobalt chelatase, distinct from CbiK or CbiXL. Based upon the ESI-MS and pH-dependent metal affinity data, in addition to available structural data, Co(II) is most likely ligated by His10 and His74.

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Crossref · 10.1021/acs.inorgchem.6c00056

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Citations

Cites

Research works printed but not linked: 4

  1. Figgis B. N., 1966, Ligand Field Theory and Its Applications
  2. Bevington P. R., 2002, Data Reduction and Error Analysis for the Physical Sciences
  3. Fujishiro T., 2022, Encyclopedia of inorganic and bioinorganic chemistry
  4. 10.26434/chemrxiv-2025-0d699 · doi:10.26434/chemrxiv-2025-0d699

Metadata

Authors
Morris, J. A., Ayodele-Davis, O. O. E., Lavigne, M. E., Martorelli Di Genova, B., & Liptak, M. D.
Affiliations
  • University of Vermont (US)
  • Department of Microbiology and Molecular Genetics
Corresponding author
Liptak, Matthew D.
Venue
Inorganic Chemistry
Published
2026-03-31
Volume
65
Issue
14
Pages
7848-7858
ISSN
  • 0020-1669 (ISSN-L)
  • 1520-510X
OpenAlex
W7143824341
Cited by
3
References
60
Citations by year
2026: 3
FWCI
2.56
Type
journal article
Language
en
Open access
Locations
  • Inorganic Chemistry (publishedVersion)
  • ChemRxiv (acceptedVersion, cc-by-nc-nd)
  • PubMed (publishedVersion)
Funders
Division of Chemistry (CHE-2003627)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Biochemistry › Metalloenzymes and iron-sulfur proteins
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Porphyrin Metabolism and Disorders
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Structural Biology › Enzyme Structure and Function
Keywords
Archaeoglobus fulgidus, cobalt(II) coordination, histidine ligands, vitamin B12 biosynthesis, divalent metal binding, Irving-Williams series, protein folding, archaeal enzyme
MeSH terms
Cobalt, Histidine, Models, Molecular, Nickel, Archaeoglobus fulgidus

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