Mucorales Tpt1 proteins have tRNA 2′-phosphotransferase activity in vivo. (A) Alignment of the amino acid sequences of Tpt1 homologs from M. circinelloides (Genbank EPB89638.1), R. azygosporus (Genbank RCI00563.1), and L. corymbifera (Genbank CDH53741.1). Positions of side chain identity/similarity are indicated by dots above the alignment. The conserved amino acids that make atomic contacts with Tpt1 reaction substrates and products are highlighted in yellow shading. (B) Complementation of S. cerevisiae tpt1Δ was assayed by plasmid shuffle. Aliquots (3 µL) of serial tenfold dilutions of FOA-resistant tpt1Δ strains expressing the indicated TPT1 genes were spotted on YPD agar plates and incubated at 20°C, 25°C, 30°C, 34°C, and 37°C. Photographs of the plates are shown.
