Linked Life Data

21539325

Source:http://linkedlifedata.com/resource/pubmed/id/21539325

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
21
pubmed:dateCreated
2011-5-24
pubmed:databankReference
pubmed:abstractText
The salvage pathways of nucleotide biosynthesis are more diverse and are less well understood as compared with de novo pathways. Uridine-cytidine kinase (UCK) is the rate-limiting enzyme in the pyrimidine-nucleotide salvage pathway. In this study, we have characterized a UCK homologue of Thermus thermophilus HB8 (ttCK) biochemically and structurally. Unlike other UCKs, ttCK had substrate specificity toward only cytidine and showed no inhibition by UTP, suggesting uridine does not bind to ttCK as substrate. Structural analysis revealed that the histidine residue located near the functional group at position 4 of cytidine or uridine in most UCKs is substituted with tyrosine, Tyr93, in ttCK. Replacement of Tyr93 by histidine or glutamine endowed ttCK with phosphorylation activity toward uridine. These results suggested that a single amino acid residue, Tyr93, gives cytidine-limited specificity to ttCK. However, replacement of Tyr93 by Phe or Leu did not change the substrate specificity of ttCK. Therefore, we conclude that a residue at this position is essential for the recognition of uridine by UCK. In addition, thymidine phosphorylase from T. thermophilus HB8 was equally active with thymidine and uridine, which indicates that this protein is the sole enzyme metabolizing uridine in T. Thermophilus HB8. On the basis of these results, we discuss the pyrimidine-salvage pathway in T. thermophilus HB8.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
1520-4995
pubmed:author
pubmed:issnType
Electronic
pubmed:day
31
pubmed:volume
50
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
4597-607
pubmed:meshHeading
pubmed:year
2011
pubmed:articleTitle
A single amino acid limits the substrate specificity of Thermus thermophilus uridine-cytidine kinase to cytidine.
pubmed:affiliation
Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, Japan.
pubmed:publicationType
Journal Article