Pak1 kinase regulates ribonucleoprotein granules through Sts5 for polarized growth and the glucose starvation response [article]

Joseph O. Magliozzi, James B. Moseley
2021 bioRxiv   pre-print
ABSTRACTFission yeast cells maintain a rod shape due to conserved signaling pathways that organize the cytoskeleton for polarized growth. We discovered a mechanism linking the conserved protein kinase Pak1 with cell shape through the RNA-binding protein Sts5. Pak1 prevents Sts5 association with P bodies by directly phosphorylating its intrinsically disordered region (IDR). Pak1 and the cell polarity kinase Orb6 both phosphorylate the Sts5 IDR but at distinct residues. Mutations preventing
more » ... orylation in the Sts5 IDR cause increase P body formation and defects in cell shape and polarity. Unexpectedly, when cells encounter glucose starvation, PKA signaling triggers Pak1 recruitment to P bodies with Sts5. Through retargeting experiments, we reveal that Pak1 localizes to these ribonucleoprotein (RNP) granules to promote rapid dissolution of Sts5 upon glucose addition. Our work reveals a new role for Pak1 in regulating cell shape through RNPs during normal and stressed growth conditions.
doi:10.1101/2021.02.17.431635 fatcat:pdvhis2iiraidotr6tjzgrzblq