The mpkB gene is a member of the multiple MAPK pathways in Aspergillus nidulans. The MpkB has been
known to play a key role in the asexual and sexual development and secondary metabolite production.
The MAPK kinase MkkB can be phosphorylated at Ser218 and Thr222 residues within the activation loop
site by SteC MAPKK kinase and consequently, activates MpkB by phosphorylating at threonine and
tyrosine residues of MpkB in A. nidulans. By introducing negatively charged (aspartic acid) or non-polar
(proline and lysine) residues that may mimic the effect of phosphorylation at positions 218 and 222 in
MkkB, we constructed mutants which constitutively phosphorylate MpkB MAPK and constitutively nonphosphorylate
MpkB MAPK. Expression of the constitutively activated MkkB in A. nidulans led to the
hyper-activation of MpkB MAPK and resulted in a great elevation of sexual development, while asexual
sporulation was remarkably reduced. In contrast, constitutively inactivated MkkB mutant could not
produce sexual organs, while asexual sporulation and sterigmatocystin production were normally
processed. Differential expression pattern of proteins among these mutants were analyzed by using the
2D proteomic analysis, which revealed that expression level of 375 spots are significantly different.
Full conference title:
- Asperfest 14 (2017)