Fig 5. The phylogenetic tree of fungal MAPKs those contain a novel activation loop motif and all representative MAPKs of A. thaliana and O. sativa.

The phylogenetic tree was constructed by taking all MAPKs of O. sativa and A. thaliana with MAPKs of fungi that contains only a “novel” activation loop motif [except one, i.e MbMPK (it contains a T-E-Y motif)]. The phylogenetic tree resulted into four different groups (red and lime color groups are plant-specific and magenta and blue colors are fungi-specific). OsMPKs and AtMPKs were grouped with AkMPK (T-T-Y motif) and AlMPK (T-I-Y motif) of fungi. This suggests that AkMPKs and AlMPKs which contains the T-T-Y and T-I-Y motifs can also be plant-specific as well, which is yet to be elucidated. The other MAPKs having T-N-Y, T-H-Y, T-S-Y, K-G-Y, T-Q-Y and S-E-Y activation loop motifs are those that fall into unique groups, which are specific to fungi only. The activation loop T-E-Y motif is very common and present in all three domains (plant, animal and fungi) of life. Therefore, one MAPK from fungi that contained the T-E-Y (MbMPK) motif was included in this study to better understand their grouping system and phylogenetic relationship. Owing to the presence of the T-E-Y motif, MbMPK is placed in between fungi and plant. Because the T-E-Y motif is common to all the three domains of life and others are unique to fungi, hence MbMPK is present in between the plant and fungi domains. ScMPK in the figure represents SLT2 of Sachharomyces cerevisiae.