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Cofactor mobility determines reaction outcome in the IMPDH and GMPR (β-α)8 barrel enzymes

Patton, Gregory C ; Stenmark, Pål LU orcid ; Gollapalli, Deviprasad R ; Sevastik, Robin ; Kursula, Petri ; Flodin, Susanne ; Schuler, Herwig LU orcid ; Swales, Colin T ; Eklund, Hans and Himo, Fahmi , et al. (2011) In Nature Chemical Biology 7(12). p.8-950
Abstract

Inosine monophosphate dehydrogenase (IMPDH) and guanosine monophosphate reductase (GMPR) belong to the same structural family, share a common set of catalytic residues and bind the same ligands. The structural and mechanistic features that determine reaction outcome in the IMPDH and GMPR family have not been identified. Here we show that the GMPR reaction uses the same intermediate E-XMP* as IMPDH, but in this reaction the intermediate reacts with ammonia instead of water. A single crystal structure of human GMPR type 2 with IMP and NADPH fortuitously captures three different states, each of which mimics a distinct step in the catalytic cycle of GMPR. The cofactor is found in two conformations: an 'in' conformation poised for hydride... (More)

Inosine monophosphate dehydrogenase (IMPDH) and guanosine monophosphate reductase (GMPR) belong to the same structural family, share a common set of catalytic residues and bind the same ligands. The structural and mechanistic features that determine reaction outcome in the IMPDH and GMPR family have not been identified. Here we show that the GMPR reaction uses the same intermediate E-XMP* as IMPDH, but in this reaction the intermediate reacts with ammonia instead of water. A single crystal structure of human GMPR type 2 with IMP and NADPH fortuitously captures three different states, each of which mimics a distinct step in the catalytic cycle of GMPR. The cofactor is found in two conformations: an 'in' conformation poised for hydride transfer and an 'out' conformation in which the cofactor is 6 Å from IMP. Mutagenesis along with substrate and cofactor analog experiments demonstrate that the out conformation is required for the deamination of GMP. Remarkably, the cofactor is part of the catalytic machinery that activates ammonia.

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publishing date
type
Contribution to journal
publication status
published
keywords
Biocatalysis, Crystallography, X-Ray, GMP Reductase/chemistry, Guanosine Monophosphate/biosynthesis, Humans, IMP Dehydrogenase/chemistry, Inosine Monophosphate/chemistry, Kinetics, Models, Molecular, Molecular Structure, NADP/chemistry, Quantum Theory, Sulfhydryl Compounds/chemistry
in
Nature Chemical Biology
volume
7
issue
12
pages
9 pages
publisher
Nature Publishing Group
external identifiers
  • scopus:81355146320
  • pmid:22037469
ISSN
1552-4469
DOI
10.1038/nchembio.693
language
English
LU publication?
no
id
c032fce0-ba21-47eb-8d1f-c652abda902e
date added to LUP
2024-11-21 17:58:56
date last changed
2025-03-14 13:10:24
@article{c032fce0-ba21-47eb-8d1f-c652abda902e,
  abstract     = {{<p>Inosine monophosphate dehydrogenase (IMPDH) and guanosine monophosphate reductase (GMPR) belong to the same structural family, share a common set of catalytic residues and bind the same ligands. The structural and mechanistic features that determine reaction outcome in the IMPDH and GMPR family have not been identified. Here we show that the GMPR reaction uses the same intermediate E-XMP* as IMPDH, but in this reaction the intermediate reacts with ammonia instead of water. A single crystal structure of human GMPR type 2 with IMP and NADPH fortuitously captures three different states, each of which mimics a distinct step in the catalytic cycle of GMPR. The cofactor is found in two conformations: an 'in' conformation poised for hydride transfer and an 'out' conformation in which the cofactor is 6 Å from IMP. Mutagenesis along with substrate and cofactor analog experiments demonstrate that the out conformation is required for the deamination of GMP. Remarkably, the cofactor is part of the catalytic machinery that activates ammonia.</p>}},
  author       = {{Patton, Gregory C and Stenmark, Pål and Gollapalli, Deviprasad R and Sevastik, Robin and Kursula, Petri and Flodin, Susanne and Schuler, Herwig and Swales, Colin T and Eklund, Hans and Himo, Fahmi and Nordlund, Pär and Hedstrom, Lizbeth}},
  issn         = {{1552-4469}},
  keywords     = {{Biocatalysis; Crystallography, X-Ray; GMP Reductase/chemistry; Guanosine Monophosphate/biosynthesis; Humans; IMP Dehydrogenase/chemistry; Inosine Monophosphate/chemistry; Kinetics; Models, Molecular; Molecular Structure; NADP/chemistry; Quantum Theory; Sulfhydryl Compounds/chemistry}},
  language     = {{eng}},
  month        = {{10}},
  number       = {{12}},
  pages        = {{8--950}},
  publisher    = {{Nature Publishing Group}},
  series       = {{Nature Chemical Biology}},
  title        = {{Cofactor mobility determines reaction outcome in the IMPDH and GMPR (β-α)<sub>8</sub> barrel enzymes}},
  url          = {{http://dx.doi.org/10.1038/nchembio.693}},
  doi          = {{10.1038/nchembio.693}},
  volume       = {{7}},
  year         = {{2011}},
}