Structure of E. coli 5′-methylthioadenosine/S-adenosylhomocysteine nucleosidase reveals similarity to the purine nucleoside phosphorylases

J. E. Lee, K. A. Cornell, Michael Riscoe, P. L. Howell

Research output: Contribution to journalArticle

69 Citations (Scopus)

Abstract

Background: 5′-methylthioadenosine/S-adenosylhomocysteine (MTA/AdoHcy) nucleosidase catalyzes the irreversible cleavage of 5′-methylthioadenosine and S-adenosylhomocysteine to adenine and the corresponding thioribose, 5′-methylthioribose and S-ribosylhomocysteine, respectively. While this enzyme is crucial for the metabolism of AdoHcy and MTA nucleosides in many prokaryotic and lower eukaryotic organisms, it is absent in mammalian cells. This metabolic difference represents an exploitable target for rational drug design. Results: The crystal structure of E. coli MTA/AdoHcy nucleosidase was determined at 1.90 Å resolution with the multiwavelength anomalous diffraction (MAD) technique. Each monomer of the MTA/AdoHcy nucleosidase dimer consists of a mixed α/β domain with a nine-stranded mixed β sheet, flanked by six α helices and a small 310 helix. Intersubunit contacts between the two monomers present in the asymmetric unit are mediated primarily by helix-helix and helix-loop hydrophobic interactions. The unexpected presence of an adenine molecule in the active site of the enzyme has allowed the identification of both substrate binding and potential catalytic amino acid residues. Conclusions: Although the sequence of E. coli MTA/AdoHcy nucleosidase has almost no identity with any known enzyme, its tertiary structure is similar to both the mammalian (trimeric) and prokaryotic (hexameric) purine nucleoside phosphorylases. The structure provides evidence that this protein is functional as a dimer and that the dual specificity for MTA and AdoHcy results from the truncation of a helix. The structure of MTA/AdoHcy nucleosidase is the first structure of a prokaryotic nucleoside N-ribohydrolase specific for 6-aminopurines.

Original languageEnglish (US)
Pages (from-to)941-953
Number of pages13
JournalStructure
Volume9
Issue number10
DOIs
StatePublished - 2001
Externally publishedYes

Fingerprint

adenosylhomocysteine nucleosidase
Purine-Nucleoside Phosphorylase
Pemetrexed
Adenine
Escherichia coli
Enzymes
S-Adenosylhomocysteine
Drug Design
Hydrophobic and Hydrophilic Interactions
Nucleosides
Catalytic Domain
Amino Acids
Proteins

Keywords

  • 5′-Methylthioadenosine/S-adenosylhomocysteine nucleosidase
  • Enzyme mechanism
  • Methionine recycling pathway
  • Methylthioadenosine phosphorylase
  • Purine nucleoside phosphorylase
  • Structure-based drug design

ASJC Scopus subject areas

  • Molecular Biology
  • Structural Biology

Cite this

Structure of E. coli 5′-methylthioadenosine/S-adenosylhomocysteine nucleosidase reveals similarity to the purine nucleoside phosphorylases. / Lee, J. E.; Cornell, K. A.; Riscoe, Michael; Howell, P. L.

In: Structure, Vol. 9, No. 10, 2001, p. 941-953.

Research output: Contribution to journalArticle

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title = "Structure of E. coli 5′-methylthioadenosine/S-adenosylhomocysteine nucleosidase reveals similarity to the purine nucleoside phosphorylases",
abstract = "Background: 5′-methylthioadenosine/S-adenosylhomocysteine (MTA/AdoHcy) nucleosidase catalyzes the irreversible cleavage of 5′-methylthioadenosine and S-adenosylhomocysteine to adenine and the corresponding thioribose, 5′-methylthioribose and S-ribosylhomocysteine, respectively. While this enzyme is crucial for the metabolism of AdoHcy and MTA nucleosides in many prokaryotic and lower eukaryotic organisms, it is absent in mammalian cells. This metabolic difference represents an exploitable target for rational drug design. Results: The crystal structure of E. coli MTA/AdoHcy nucleosidase was determined at 1.90 {\AA} resolution with the multiwavelength anomalous diffraction (MAD) technique. Each monomer of the MTA/AdoHcy nucleosidase dimer consists of a mixed α/β domain with a nine-stranded mixed β sheet, flanked by six α helices and a small 310 helix. Intersubunit contacts between the two monomers present in the asymmetric unit are mediated primarily by helix-helix and helix-loop hydrophobic interactions. The unexpected presence of an adenine molecule in the active site of the enzyme has allowed the identification of both substrate binding and potential catalytic amino acid residues. Conclusions: Although the sequence of E. coli MTA/AdoHcy nucleosidase has almost no identity with any known enzyme, its tertiary structure is similar to both the mammalian (trimeric) and prokaryotic (hexameric) purine nucleoside phosphorylases. The structure provides evidence that this protein is functional as a dimer and that the dual specificity for MTA and AdoHcy results from the truncation of a helix. The structure of MTA/AdoHcy nucleosidase is the first structure of a prokaryotic nucleoside N-ribohydrolase specific for 6-aminopurines.",
keywords = "5′-Methylthioadenosine/S-adenosylhomocysteine nucleosidase, Enzyme mechanism, Methionine recycling pathway, Methylthioadenosine phosphorylase, Purine nucleoside phosphorylase, Structure-based drug design",
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T1 - Structure of E. coli 5′-methylthioadenosine/S-adenosylhomocysteine nucleosidase reveals similarity to the purine nucleoside phosphorylases

AU - Lee, J. E.

AU - Cornell, K. A.

AU - Riscoe, Michael

AU - Howell, P. L.

PY - 2001

Y1 - 2001

N2 - Background: 5′-methylthioadenosine/S-adenosylhomocysteine (MTA/AdoHcy) nucleosidase catalyzes the irreversible cleavage of 5′-methylthioadenosine and S-adenosylhomocysteine to adenine and the corresponding thioribose, 5′-methylthioribose and S-ribosylhomocysteine, respectively. While this enzyme is crucial for the metabolism of AdoHcy and MTA nucleosides in many prokaryotic and lower eukaryotic organisms, it is absent in mammalian cells. This metabolic difference represents an exploitable target for rational drug design. Results: The crystal structure of E. coli MTA/AdoHcy nucleosidase was determined at 1.90 Å resolution with the multiwavelength anomalous diffraction (MAD) technique. Each monomer of the MTA/AdoHcy nucleosidase dimer consists of a mixed α/β domain with a nine-stranded mixed β sheet, flanked by six α helices and a small 310 helix. Intersubunit contacts between the two monomers present in the asymmetric unit are mediated primarily by helix-helix and helix-loop hydrophobic interactions. The unexpected presence of an adenine molecule in the active site of the enzyme has allowed the identification of both substrate binding and potential catalytic amino acid residues. Conclusions: Although the sequence of E. coli MTA/AdoHcy nucleosidase has almost no identity with any known enzyme, its tertiary structure is similar to both the mammalian (trimeric) and prokaryotic (hexameric) purine nucleoside phosphorylases. The structure provides evidence that this protein is functional as a dimer and that the dual specificity for MTA and AdoHcy results from the truncation of a helix. The structure of MTA/AdoHcy nucleosidase is the first structure of a prokaryotic nucleoside N-ribohydrolase specific for 6-aminopurines.

AB - Background: 5′-methylthioadenosine/S-adenosylhomocysteine (MTA/AdoHcy) nucleosidase catalyzes the irreversible cleavage of 5′-methylthioadenosine and S-adenosylhomocysteine to adenine and the corresponding thioribose, 5′-methylthioribose and S-ribosylhomocysteine, respectively. While this enzyme is crucial for the metabolism of AdoHcy and MTA nucleosides in many prokaryotic and lower eukaryotic organisms, it is absent in mammalian cells. This metabolic difference represents an exploitable target for rational drug design. Results: The crystal structure of E. coli MTA/AdoHcy nucleosidase was determined at 1.90 Å resolution with the multiwavelength anomalous diffraction (MAD) technique. Each monomer of the MTA/AdoHcy nucleosidase dimer consists of a mixed α/β domain with a nine-stranded mixed β sheet, flanked by six α helices and a small 310 helix. Intersubunit contacts between the two monomers present in the asymmetric unit are mediated primarily by helix-helix and helix-loop hydrophobic interactions. The unexpected presence of an adenine molecule in the active site of the enzyme has allowed the identification of both substrate binding and potential catalytic amino acid residues. Conclusions: Although the sequence of E. coli MTA/AdoHcy nucleosidase has almost no identity with any known enzyme, its tertiary structure is similar to both the mammalian (trimeric) and prokaryotic (hexameric) purine nucleoside phosphorylases. The structure provides evidence that this protein is functional as a dimer and that the dual specificity for MTA and AdoHcy results from the truncation of a helix. The structure of MTA/AdoHcy nucleosidase is the first structure of a prokaryotic nucleoside N-ribohydrolase specific for 6-aminopurines.

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KW - Methionine recycling pathway

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KW - Purine nucleoside phosphorylase

KW - Structure-based drug design

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