Research on actin networks of the “frog-killing fungus” Bd is published in Current Biology.
- by Lillian Fritz-Laylin
- in News
- posted February 8, 2021
Sarah Prostak, Kristyn Robinson, along with Margart Titus from the University of Minnesota have published their work “The actin networks of chytrid fungi reveal evolutionary loss of cytoskeletal complexity in the fungal kingdom” in Current Biology (you can read the paper here!). First author Sarah started this work as an undergraduate for her thesis and continued it after graduation. In the paper we show that chytrid fungi have actin networks resembling both those of animals and of yeast, providing an excellent system to study actin evolution in the animal and fungal lineages.
Here’s the abstract: Cells from across the eukaryotic tree use actin polymer networks for a wide variety of functions, including endocytosis, cytokinesis, and cell migration. Despite this functional conservation, the actin cytoskeleton has undergone significant diversification, highlighted by the differeSarah Prostaknces in the actin networks of mammalian cells and yeast. Chytrid fungi diverged before the emergence of the Dikarya (multicellular fungi and yeast) and therefore provide a unique opportunity to study actin cytoskeletal evolution. Chytrids have two life stages: zoospore cells that can swim with a flagellum and sessile sporangial cells that, like multicellular fungi, are encased in a chitinous cell wall. Here, we show that zoospores of the amphibian-killing chytrid Batrachochytrium dendrobatidis (Bd) build dynamic actin structures resembling those of animal cells, including an actin cortex, pseudopods, and filopodia-like spikes. In contrast, Bd sporangia assemble perinuclear actin shells and actin patches similar to those of yeast. The use of specific small-molecule inhibitors indicate that nearly all of Bd’s actin structures are dynamic and use distinct nucleators: although pseudopods and actin patches are Arp2/3 dependent, the actin cortex appears formin dependent and actin spikes require both nucleators. Our analysis of multiple chytrid genomes reveals actin regulators and myosin motors found in animals, but not dikaryotic fungi, as well as fungal-specific components. The presence of animal- and yeast-like actin cytoskeletal components in the genome combined with the intermediate actin phenotypes in Bd suggests that the simplicity of the yeast cytoskeleton may be due to evolutionary loss.