Crystal structure of yeast cytosine deaminase: Insights into enzyme mechanism and evolution

Tzu Ping Ko, Jing Jer Lin, Chih Yung Hu, Yi Hsin Hsu, Andrew H.J. Wang, Shwu Huey Liaw

研究成果: 雜誌貢獻文章同行評審

97 引文 斯高帕斯(Scopus)


Yeast cytosine deaminase is an attractive candidate for anticancer gene therapy because it catalyzes the deamination of the prodrug 5-fluorocytosine to form 5-fluorouracil. We report here the crystal structure of the enzyme in complex with the inhibitor 2-hydroxypyrimidine at 1.6-A resolution. The protein forms a tightly packed dimer with an extensive interface of 1450 Å2 per monomer. The inhibitor was converted into a hydrated adduct as a transition-state analog. The essential zinc ion is ligated by the 4-hydroxyl group of the inhibitor together with His62, Cys91, and Cys94 from the protein. The enzyme shares similar active-site architecture to cytidine deaminases and an unusually high structural homology to 5-aminoimidazole-4-carboxamide-ribonucleotide transformylase and thereby may define a new superfamily. The unique C-terminal tail is involved in substrate specificity and also functions as a gate controlling access to the active site. The complex structure reveals a closed conformation, suggesting that substrate binding seals the active-site entrance so that the catalytic groups are sequestered from solvent. A comparison of the crystal structures of the bacterial and fungal cytosine deaminases provides an elegant example of convergent evolution, where starting from unrelated ancestral proteins, the same metal-assisted deamination is achieved through opposite chiral intermediates within distinctly different active sites.

頁(從 - 到)19111-19117
期刊Journal of Biological Chemistry
出版狀態已發佈 - 5月 23 2003

ASJC Scopus subject areas

  • 生物化學
  • 分子生物學
  • 細胞生物學


深入研究「Crystal structure of yeast cytosine deaminase: Insights into enzyme mechanism and evolution」主題。共同形成了獨特的指紋。