Effects Of Aspergillus Nidulans Membrane Formation Regulatory Protein MobA And Silanine Phosphatase PP2A Regulating Subunit PabA On Producing And Sporulation

Proper completion of mitosis requires careful coordination of numerous cellular events. It is crucial for cells do not initiate spindle disassembly and cytokinesis until chromosomes have been properly segregated. Cells have developed numerous safeguards or checkpoints to delay exit from mitosis and initiation of the next cell cycle in response to defects in late mitosis. For example, there are two homologous signaling pathways in budding and fission yeasts, termed the mitotic exit network (MEN) and the septation initiation network (SIN), respectively, that are essential for coordinating completion of mitosis and cytokinesis with other mitotic events. Research of the SIN in Aspergillus nidulans is figured out by Harris through comparison between A. nidulans and yeast, implying that a signaling network resembling the SIN in fission yeast likely regulates septation, but there are still many different components and regulation ways in A. nidulans.As an evolutionarily conserved SIN protein, MobA plays an important role in septation and conidiation, To gain insight into this regulatory mechanisms, we consequently used conditional mutations in which the mobA gene was under the control of the inducible/repressible alcA promoter. Our research indicated that except septation and conidiation, mobA participates in hyphal growth. The diameter of A. nidulans colony is decreasing when we using higher spore density, this result suggests that loss of mobA will weaken the competition ability of spores on nutrition utilization. During septation, GFP-MobA decorated both the spindle pole body and the septation site. In addition, self-fertilization experiment result shows that mobA has little influence on A. nidulans sexual crossing.Protein phosphatase 2A (PP2A) comprises a large family of heterotrimeric complexes required for a variety of cellular processes. Our previous work showed its regulatory subunit PabA play an important role in hyphal growth and cytokinesis, loss of PabA brings septation delay, we trying to explain this situation. The second part of this reseach is figure on interaction between PabA and MobA. The observation to sexual-crossing progeny between alc-gfp-mobA and ApabA suggest that PabA acts upstream of MobA, as the regulatory subunit of PP2A, PabA has comprehensive function on growth development. Moreover, pabA deletion is capable of suppressing septation defects in mobA mutants, suggesting that PabA counteracts mobA during the septation process. When we over expressed mobA strongly by gpd promoter, location of PabA is changed to SPB and septem from nuclei, demonstrates there are some linkers between PabA and MobA although physical interaction between MobA and PabA is not verified by yeast two-hybrid system.Thus, our findings support that MobA is required for septation, conidiation and hyphal growth, there are some linkers between PabA and MobA although they do not have physical interaction directly in Aspergillus nidulans,.This finding will provide an theoretic foundation for us to figure out the role of PP2A in cytokinesis.