3ASY

ligand-free structure of uridine kinase from thermus thermophilus HB8

3ASY の概要

• エントリーDOI: 10.2210/pdb3asy/pdb
• 関連するPDBエントリー: 3ASZ
• 分子名称: Uridine kinase (2 entities in total)
• 機能のキーワード: cytidine phosphorylation, transferase
• 由来する生物種: Thermus thermophilus
• 細胞内の位置: Cytoplasm (By similarity): Q5SKR5
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 47419.45

構造登録者

Tomoike, F.,Nakagawa, N.,Kuramitsu, S.,Masui, R. (登録日: 2010-12-22, 公開日: 2011-06-01, 最終更新日: 2024-04-03)

主引用文献

Tomoike, F.,Nakagawa, N.,Kuramitsu, S.,Masui, R.
A Single Amino Acid Limits the Substrate Specificity of Thermus thermophilus Uridine-Cytidine Kinase to Cytidine
Biochemistry, 50:4597-4607, 2011

PubMed Abstract: 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: 21539325
DOI: 10.1021/bi102054n

実験手法

X-RAY DIFFRACTION (2.4 Å)