FIGURE 4.

The WY-domain is a conserved unit in Phytophthora RXLR effectors. a, the MEME motif spanning the WY-domain identified by searching the RXLR repertoire of P. infestans, P. ramorum, and P. sojae. Boxed residues, from left to right are the Leu of the L-motif, the Trp of the W-motif, the residues from α₃ (AVR3a11) that pack into the hydrophobic core (Val and Leu), and the Tyr of the Y-motif (and the conserved hydrophobic residue two positions before). b, graphical representation of the final HMM model used to screen the Phytophthora and H. arabidopsidis effector repertoires for the presence of the WY-domain. The four most abundant amino acids at each position in the motif are labeled with their one-letter code, and those that represented ≥20% are shaded in gray. c, distribution of WY-domains in RXLR effectors (top) and the non-RXLR proteome (bottom, stacked bar chart) following sequence database searches with the WY-domain HMM. The number of proteins in each HMM score bin is shown. The positions of AVR3a and PexRD2 are marked, and the dashed line shows the position of the cut-off used to describe WY-domain like sequences. The estimated false positive rate of WY-domain discovery based on the Phytophthora non-RXLR secretome is also shown (bottom, line graph).