Fig. 2

Validation of the Pb257 signal peptide by a yeast invertase secretion assay. The predicted signal peptide sequence of Pb257 was fused in-frame to the yeast mature invertase sequence in the pSUC2 vector and expressed in YTK12. The functional signal peptide enabled yeast growth on YPRAA medium with raffinose as the sole carbon source (1% yeast extract, 2% peptone, 2% raffinose, and 2 µg antimycin A per liter) and CMD-W medim (0.67% yeast N base without amino acids, 0.075% tryptophan dropout supplement, 2% sucrose, 0.1% glucose, and 2% agar). N-terminal sequences of P. sojae Avr1b and M. oryzae Mg87 were used as positive and negative controls, respectively. The untransformed YTK12 did not grow on either CMD-W or YPRAA media. Yeast growth on CMD-W medium was equally viable among the transformed strains