Analyzing Protein Kinase C Domain Interactions with the Formin SepA

Abstract

This research focuses on understanding polarized growth in filamentous fungi. In the model organism Aspergillus nidulans and other filamentous fungi, polarized growth is focused at both the hyphal tip and septa, and growth at both areas involves deposition of cell wall material. To better understand polarized growth, we study proteins that localize to growing hyphal tips and forming septa. In A. nidulans, protein kinase C (PkcA) is involved in the organism's cell wall stress response, and our previous work uncovered a protein‐protein interaction between PkcA and the formin SepA. We also illustrated complementary roles of the two proteins in growth and cell wall integrity. Both PkcA and SepA localize to hyphal tips and septation sites. Using bimolecular fluorescence complementation, we found that SepA and PkcA physically interact at both sub‐cellular locations, and that this interaction occurs through amino acid residues within the C‐terminal half of SepA. Previously, we showed using a series of fluorescence‐labeled PkcA truncated proteins that two regions of PkcA are responsible for PkcA localizing to hyphal tips and septation sites. The first region is a 10 amino‐acid sequence near the carboxyl end of the C2 domain that is required for localization to hyphal tips and septation sites, while the second region is between the C2 and C1B domain, and is sufficient for localization to septation sites only. Here we present our progress towards determining which PkcA domains are involved in its interaction with SepA by using the previously published PkcA truncations in Gal4‐based yeast two hybrid assays. These results help to shed light on the mechanism underlying SepA's and PkcA's complementary involvement in polarized growth.Support or Funding InformationNational Science Foundation Grant 1615192 (Loretta Jackson‐Hayes, PI)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.