a- Topology diagram of YLF030w. The N-terminal extension is colored in blue, the N-terminal domain is colored in red/orange and the C-terminal domain is colored in green. b- Stereo cartoon presentation of the structure of YLF030w monomer. The lysine-PLP is in blue sticks. Same color code as for Figure 1a. c- Stereo cartoon presentation of the structure of YLF030w dimer. One subunit is colored in cyan blue, the second is colored as in Figure 1a. The two active sites at the interface of the subunits are shown with the lysine-PLP in blue sticks.

We have determined the three-dimensional crystal structure of the protein encoded by the open reading frame YFL030w from Saccharomyces cerevisiae to a resolution of 2.6 Å using single wavelength anomalous diffraction. YFL030w is a 385 amino-acid protein with sequence similarity to the aminotransferase family. The structure of the protein reveals a homodimer adopting the fold-type I of pyridoxal 5_-phosphate (PLP)-dependent aminotransferases. The PLP co-factor is covalently bound to the active site in the crystal structure. The protein shows close structural resemblance with the human alanine:glyoxylate aminotransferase (EC 2.6.1.44), an enzyme involved in the hereditary kidney stone disease primary hyperoxaluria type 1. In this paper we show that YFL030w codes for an alanine:glyoxylate aminotransferase, highly specific for its amino donor and acceptor substrates.