In silico identification of MAPK3/6 substrates in WRKY, bZIP, MYB, MYB- related, NAC and AP-2 transcription factor family in Arabidopsis thaliana

Mitogen activated protein kinases (MAPKs) are key proteins involved in the signal transduction of extracellular information to intracellular targets and plays essential role in the response to biotic and abiotic stresses. We have identified the important determinants or motif for substrate specificity of MAPK3/6 with six major transcription factors viz., AP2, bZIP, MYB, MYB-related, NAC and WRKY, SP and TP sites; which are serine and threonine specific phosphorylation sites. Netphos 2.0 server was used to predict 101 SP, 62 TP out of 147 substrates in AP2; 44 SP, 31 TP out of 70 substrates in bZIP; 98 SP, 81 TP out of 150 substrates in MYB; 38 SP, 27 TP out of 49 substrates in MYB-related; 64 SP, 29 TP out of 101 substrates in NAC and 53 SP, 32 TP out of 72 substrates in WRKY. We have also found proline residue is present at +1 position of all phosphorylation sites that means proline might play an important role to enhance the binding affinity of MAPK3/6 with different transcription factors. Although, further functional analysis through wet lab experimentation will be required, our study provides the basis for future research on the complex signaling pathway mediated by MAPK with its substrates in Arabidopsis thaliana and related plant species.