Biology subjects

Wirshing, A. C. E.

Publications and source records attributed to Wirshing, A. C. E..

4 recordsLinked to original sources

bioRxiv2026

Septins and cytokinesis in the polymorphic fungus Aureobasidium pullulans

During cytokinesis of animals and fungi, a contractile actomyosin ring (CAR) assembles at target locations and constricts to drive cell separation. In animal cells, the position of the CAR is determined by the mitotic spindle, so that the cleavage plane is perpendicular to the mitotic axis. However, in budding yeasts, the location of CAR assembly is specified by a cortical septin cytoskeleton that recruits CAR components to the neck. In the polymorphic fungus Aureobasidium pullulans, we show that septins assemble at mother-bud necks and predict the site of CAR assembly. Cells lacking septins stochastically failed to assemble CARs at a subset of bud necks. However, even cells lacking all four core septins were able to assemble CARs at 75% of bud necks. Our findings suggest the existence of a novel CAR positioning strategy that requires neither septin scaffolds nor nuclear/spindle cues to enable CAR assembly and constriction at bud necks. eTOC SUMMARYBudding yeasts are thought to use septins to mark mother-bud necks as sites for cytokinesis. Here, we find that the multibudding yeast Aureobasidium pullulans can position cytokinetic machinery at most bud necks even in the absence of septins, revealing a novel pathway to mark cytokinesis sites.

cell biology↗

bioRxiv2025

Allocation of resources among multiple daughter cells

Cell division commonly produces two daughter cells, but there are many exceptions where large cells produce multiple daughters. Multiple fission of some green algae and bacteria, cellularization during embryogenesis of plants and insects, and growth of Ichthyosporeans, Chytrids, and Apicomplexans all provide variations on this theme. In some yeast species, a large multi-nucleate mother cell grows multiple buds (daughters) simultaneously. Here we address how mothers partition growth equally among their buds in the multi-budding yeast Aureobasidium pullulans. Bud growth is directed by actin cable networks that appear to be optimized for even partitioning despite complex cell geometries. Even partitioning does not rely on compensatory mechanisms to adjust bud volumes, but rather stems directly from effective equalization of polarity sites. These results reveal how conserved cell polarity and cytoskeletal networks are adapted to build complex morphologies in fungi.

cell biology↗

bioRxiv2025

Optimized vectors for genetic engineering of Aureobasidium pullulans

Aureobasidium pullulans is a polyextremotolerant black yeast that exhibits impressive morphological plasticity. Consequently, it shows promise as a model system for investigating mechanisms of cell adaptation to different environments and the regulation of cell shape. Here, we build upon the current toolkit for working with A. pullulans and design and test 25 vectors with seven different codon-optimized fluorophores and three selection cassettes. This includes vectors that allow for dual expression of GFP and mCherry tagged proteins at the URA3 locus and vectors that enable homology-based deletion or C-terminal tagging of endogenous genes without the need for cloning. This versatile vector series for working with A. pullulans will enable a broad range of experiments in this emerging model system. SUMMARYAn optimized plasmid toolkit for genetic engineering of the emerging model fungus, A. pullulans.

cell biology↗

bioRxiv2024

Negative feedback equalizes polarity sites in a multi-budding yeast

Morphogenesis in fungi and animals is directed by polarization of small GTPases Cdc42 and Rac. In the budding yeast Saccharomyces cerevisiae competition between polarity patches results in one polarized patch and the growth of a single bud. Here, we describe cell polarity in the yeast Aureobasidium pullulans, which establishes multiple coexisting polarity sites yielding multiple buds during a single cell division cycle. Polarity machinery components oscillate in their abundance in these coexisting sites but do so independently of one another, pointing to a lack of global coupling between sites. Previous theoretical work has demonstrated that negative feedback in a polarity circuit could promote coexistence of multiple polarity sites, and time-delayed negative feedback is known to cause oscillations. We show that both these features of negative feedback depend on a protein we identified as Pak1, and that Pak1 requires Rac1 but not Cdc42 for its localization. This work shows how conserved signaling networks can be modulated for distinct morphogenic programs even within the constraints of fungal budding.

cell biology↗