Roles of Inn1, Cyk3, and PaxB Proteins in Cytokinesis in the Filamentous Fungus Aspergillus nidulans

Abstract

Cytokinesis is an essential component of cellular development in filamentous fungi. The process parallels that of cell division in animal cells in requiring assembly and constriction of a contractile actomyosin ring (CAR) in the cell periphery. However, the process differs from that in animals by involving the simultaneous construction of a chitin‐rich cross wall termed a septum, which separates semi‐independent compartments of the fungal hypha. We have recently identified three genes, designated inn1, cyk3, and paxB, that we hypothesized would play roles in septum formation, based on sequence homologies to proteins performing similar functions in yeasts. GFP tagging demonstrates that the protein products encoded by these genes (Inn1, Cyk3, and PaxB, respectively) all localize to sites of septum formation and in fact colocalize with actin during at least part of CAR assembly and constriction. We have also deleted all three genes or repressed their expression using regulatable promoters, demonstrating in each case significant effects upon septation. In further work, we have generated double‐mutant strains in which a GFP‐tagged septation‐related protein is expressed in a cell that also bears a loss‐of‐function mutation in a second septation protein, demonstrating a network of interactions between inn1, cyk3, and paxB (on the one hand) and a number of previously characterized septation proteins. We will present an integrated interaction model placing the Inn1, Cyk3, and PaxB proteins within a system of interacting proteins necessary for septum formation in filamentous fungi.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.