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The Crystal Structure of Streptococcus pyogenes Uridine Phosphorylase Reveals a Distinct Subfamily of Nucleoside Phosphorylases

Tran, Timothy H.; Christoffersen, Stig LU ; Allan, Paula W.; Parker, William B.; Piskur, Jure LU ; Serra, I.; Terreni, M. and Ealick, Steven E. (2011) In Biochemistry 50(30). p.6549-6558
Abstract
Uridine phosphorylase (UP), a key enzyme in the pyrimidine salvage pathway catalyzes the reversible phosphorolysis of uridine or 2'-deoxyuridine to uracil and ribose 1-phosphate or 2'-deoxyribose 1-phosphate. This enzyme belongs to the nucleoside phosphorylase I superfamily whose members show diverse specificity for nucleoside substrates. Phylogenetic analysis shows Streptococcus pyogenes uridine phosphorylase (SpUP) is found in a distinct branch of the pyrimidine subfamily of nucleoside phosphorylases. To further characterize SpUP, we determined the crystal structure in complex with the products, ribose I-phosphate and uracil, at 1.8 angstrom resolution. Like Escherichia coli UP (EcUP), the biological unit of SpUP is a hexamer with an... (More)
Uridine phosphorylase (UP), a key enzyme in the pyrimidine salvage pathway catalyzes the reversible phosphorolysis of uridine or 2'-deoxyuridine to uracil and ribose 1-phosphate or 2'-deoxyribose 1-phosphate. This enzyme belongs to the nucleoside phosphorylase I superfamily whose members show diverse specificity for nucleoside substrates. Phylogenetic analysis shows Streptococcus pyogenes uridine phosphorylase (SpUP) is found in a distinct branch of the pyrimidine subfamily of nucleoside phosphorylases. To further characterize SpUP, we determined the crystal structure in complex with the products, ribose I-phosphate and uracil, at 1.8 angstrom resolution. Like Escherichia coli UP (EcUP), the biological unit of SpUP is a hexamer with an alpha/beta monomeric fold. A novel feature of the active site is the presence of His169, which structurally aligns with Arg168 of the EcUP structure. A second active site residue, Lys162, is not present in previously determined UP structures and interacts with O2 of uracil. Biochemical studies of wild-type SpUTP showed that its substrate specificity is similar to that of EcUP, while EcUP is similar to 7-fold more efficient than SpUP. Biochemical studies of SpUP mutants showed that mutations of His 169 reduced activity, while mutation of Lys162 abolished all activity, suggesting that the negative charge in the transition state resides mostly on uracil O2. This is in contrast to EcUP for which transition state stabilization occurs mostly at O4. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Biochemistry
volume
50
issue
30
pages
6549 - 6558
publisher
The American Chemical Society
external identifiers
  • wos:000293035500004
  • scopus:79960756791
ISSN
0006-2960
DOI
10.1021/bi200707z
language
English
LU publication?
yes
id
f2687319-b652-4aaf-b79b-e451f4cd3718 (old id 2092733)
date added to LUP
2011-08-25 13:46:13
date last changed
2017-01-15 03:23:36
@article{f2687319-b652-4aaf-b79b-e451f4cd3718,
  abstract     = {Uridine phosphorylase (UP), a key enzyme in the pyrimidine salvage pathway catalyzes the reversible phosphorolysis of uridine or 2'-deoxyuridine to uracil and ribose 1-phosphate or 2'-deoxyribose 1-phosphate. This enzyme belongs to the nucleoside phosphorylase I superfamily whose members show diverse specificity for nucleoside substrates. Phylogenetic analysis shows Streptococcus pyogenes uridine phosphorylase (SpUP) is found in a distinct branch of the pyrimidine subfamily of nucleoside phosphorylases. To further characterize SpUP, we determined the crystal structure in complex with the products, ribose I-phosphate and uracil, at 1.8 angstrom resolution. Like Escherichia coli UP (EcUP), the biological unit of SpUP is a hexamer with an alpha/beta monomeric fold. A novel feature of the active site is the presence of His169, which structurally aligns with Arg168 of the EcUP structure. A second active site residue, Lys162, is not present in previously determined UP structures and interacts with O2 of uracil. Biochemical studies of wild-type SpUTP showed that its substrate specificity is similar to that of EcUP, while EcUP is similar to 7-fold more efficient than SpUP. Biochemical studies of SpUP mutants showed that mutations of His 169 reduced activity, while mutation of Lys162 abolished all activity, suggesting that the negative charge in the transition state resides mostly on uracil O2. This is in contrast to EcUP for which transition state stabilization occurs mostly at O4.},
  author       = {Tran, Timothy H. and Christoffersen, Stig and Allan, Paula W. and Parker, William B. and Piskur, Jure and Serra, I. and Terreni, M. and Ealick, Steven E.},
  issn         = {0006-2960},
  language     = {eng},
  number       = {30},
  pages        = {6549--6558},
  publisher    = {The American Chemical Society},
  series       = {Biochemistry},
  title        = {The Crystal Structure of Streptococcus pyogenes Uridine Phosphorylase Reveals a Distinct Subfamily of Nucleoside Phosphorylases},
  url          = {http://dx.doi.org/10.1021/bi200707z},
  volume       = {50},
  year         = {2011},
}