SnRK1 phosphorylation of begomovirus Rep proteins. A, Alignment of the amino acid sequences of the begomovirus TGMV, ToMoV, TYLCV, and CaLCuV Rep protein regions containing the TGMV Rep Ser-97 (red arrow) that is phosphorylated by SnRK1. The amino acid positions for the TGMV Rep are indicated. The Arg-94 of TGMV Rep is indicated with the green arrow. Conserved amino acids in three or more of the viruses are highlighted in yellow. GRS and motif III also are indicated. B, Phosphorylation assay of His6-tagged recombinant proteins corresponding to the N-terminal halves of TGMV (lane 1), ToMoV (lane 3), TYLCV (lane 5), and CaLCuV (lane 7) Rep proteins and their S97D (lane 2), S96D (lane 4), S94D (lane 6), and D98S (lane 8) mutants, respectively. These Ser or Asp residues correspond to the TGMV Rep Ser-97. The phosphorylation reactions were resolved by SDS-PAGE and visualized by autoradiography (top gel), and the gels were stained with Coomassie Brilliant Blue (bottom gel).