Indispensable residue for uridine binding in the uridine-cytidine kinase family

Fumiaki Tomoike; Noriko Nakagawa; Kenji Fukui; Takato Yano; Seiki Kuramitsu; Ryoji Masui

doi:10.1016/j.bbrep.2017.07.002

Indispensable residue for uridine binding in the uridine-cytidine kinase family

Biochem Biophys Rep. 2017 Jul 8:11:93-98. doi: 10.1016/j.bbrep.2017.07.002. eCollection 2017 Sep.

Authors

Fumiaki Tomoike^{1

2}, Noriko Nakagawa³, Kenji Fukui⁴, Takato Yano⁴, Seiki Kuramitsu³, Ryoji Masui⁵

Affiliations

¹ Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
² Research Center for Materials Science, Nagoya University, Furo-Cho, Chikusa-ku, Nagoya 464-8602, Japan.
³ Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan.
⁴ Department of Biochemistry, Osaka Medical College, 2-7 Daigakumachi, Takatsuki, Osaka 569-8686, Japan.
⁵ Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan.

Abstract

Uridine-cytidine kinase (UCK), including human UCK2, are a family of enzymes that generally phosphorylate both uridine and cytidine. However, UCK of Thermus thermophilus HB8 (ttCK) phosphorylates only cytidine. This cytidine-restricted activity is thought to depend on Tyr93, although the precise mechanism remains unresolved. Exhaustive mutagenesis of Tyr93 in ttCK revealed that the uridine phosphorylation activity was restored only by replacement of Tyr93 with His or Gln. Replacement of His117 in human UCK2, corresponding to residue Tyr93 in ttCK, by Tyr resulted in a loss of uridine phosphorylation activity. These findings indicated that uridine phosphorylation activity commonly depends on a single residue in the UCK family.

Keywords: Crystal structure; Nucleotide metabolism; Substrate specificity; Thermus thermophilus; UCK, uridine-cytidine kinase; Uridine-cytidine kinase; hsUCK2, Homo sapiens UCK 2; ttCK, UCK (TTHA0578) in T. thermophilus HB8.