Nitrogen-obtaining and -conserving strategies in xylotrophic basidiomycetes

Voronko

2020

Preprint

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Two main systems regulate the plasmalemma tension and provide a close connection of the protoplast with the cell wall in fungi: turgor pressure and actin cytoskeleton. These systems work together with the plasmalemma focal adhesion to the cell wall and their contribution to fungal cell organization has been partially studied, but remains controversial in model filamentous ascomycetes and oomycetes, and even less investigated in filamentous basidiomycetes. Early endocytosis, in which F-actin is actively involved, can be used to research of mechanisms regulating the plasmalemma tension, since the latter influences on the primary endocytic vesicles formation. This study examined the effects of actin polymerization inhibitors and hyperosmotic shock on early endocytosis and cell morphology in two filamentous basidiomycetes. The main obtained results: (i) depolymerization of F-actin leads to the fast formation of primary endocytic vesicles but to inhibition of their scission; (ii) moderate hyperosmotic shock does not affect the dynamics of early endocytosis. These and a number of other results allowed offering a curtain model of regulation the plasmalemma tension in basidiomycetes. According to this model, the plasmalemma tension in many nonapical cells of hyphae is more often regulated not by turgor pressure, but by a system of actin driver cables that are associated with the proteins of focal adhesion sites. The change in the plasmalemma tension occurs similar to the movement of the curtain along the curtain rod using the curtain drivers. This model addresses the fundamental properties of the fungal structure and physiology and requires confirmation, including through the yet technically unavailable high quality labeling of the actin cytoskeleton of basidiomycetes.

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Section: Labeling Of Endocytic Compartments the Use Of Apis And Hypesupporting

confidence: 62%

Section: Introductionmentioning

confidence: 95%

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Early endocytosis as a key to understanding mechanisms of plasmalemma tension regulation in filamentous fungi

Voronko

2020

Preprint

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“…In filamentous basidiomycetes, issues related to the regulation of PMT are less studied than in ascomycetes. In our previous papers (Kamzolkina et al., 2017; Mazheika et al., 2020), two features of early endocytosis in filamentous basidiomycetes were described which may shed light on the mechanism of the regulation of PMT in these fungi. First, it has been shown that filamentous fungi have at least two types of endocytosis differing in the maximum size of the PEVs.…”

Section: Introductionmentioning

confidence: 96%

“…Macrovesicular endocytosis was found in a number of xylotrophic basidiomycetes and in Coprinus comatus . The size of spherical endocytic invaginations (the term EP is not suitable here) with this type of endocytosis reaches 2 μm (Mazheika et al., 2020). Obviously, such large invaginations of the plasma membrane are not compatible with high turgor pressure (too much power is required from the actin structures).…”

Section: Introductionmentioning

confidence: 99%

Early endocytosis as a key to understanding mechanisms of plasma membrane tension regulation in filamentous fungi

Voronko

2020

Biology of the Cell

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Background Information. Two main systems regulate plasma membrane tension (PMT) and provide a close connection between the protoplast and the cell wall in fungi: turgor pressure and the actin cytoskeleton. These systems work together with the plasma membrane focal adhesion to the cell wall and their contribution to fungal cell organization and physiology has been partially studied. However, it remains controversial in model filamentous ascomycetes and oomycetes and even less investigated in filamentous basidiomycetes. Early endocytosis can be used to research the mechanisms regulating PMT since the dynamics of early endocytosis is largely dependent on this tension. Results. This study examined the effects of actin polymerization inhibitors and hyperosmotic shock on early endocytosis and cell morphology in two filamentous basidiomycetes. The main obtained results are: (i) the depolymerisation of F-actin leads to the fast formation of endocytic pits while inhibiting of their scission from the plasma membrane and (ii) the moderate hyperosmotic shock does not affect the dynamics of early endocytosis. These and our other results have allowed suggesting a curtain model for the regulation of PMT in basidiomycetes. Conclusions and significance. According to the proposed curtain model, the PMT in many non-apical cells of hyphae is more often regulated not by turgor pressure but by a system of actin driver cables that are associated with the proteins of the focal adhesion sites. The change in PMT occurs similar to the movement of a curtain along the curtain rod using the curtain drivers. This model addresses the fundamental properties of the fungal structure and physiology. It requires confirmation including the currently technically unavailable high-quality labelling of the actin cytoskeleton of the basidiomycetes.

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Does macrovesicular endocytosis occur in fungal hyphae?

2021

Fungal Biology Reviews