Eisosome Organization in the Filamentous AscomyceteAspergillus nidulans

Abstract

Eisosomes are subcortical organelles implicated in endocytosis and have hitherto been described only in Saccharomyces cerevisiae. They comprise two homologue proteins, Pil1 and Lsp1, which colocalize with the transmembrane protein Sur7. These proteins are universally conserved in the ascomycetes. We identify in Aspergillus nidulans (and in all members of the subphylum Pezizomycotina) two homologues of Pil1/Lsp1, PilA and PilB, originating from a duplication independent from that extant in the subphylum Saccharomycotina. In the aspergilli there are several Sur7-like proteins in each species, including one strict Sur7 orthologue (SurG in A. nidulans). In A. nidulans conidiospores, but not in hyphae, the three proteins colocalize at the cell cortex and form tightly packed punctate structures that appear different from the clearly distinct eisosome patches observed in S. cerevisiae. These structures are assembled late during the maturation of conidia. In mycelia, punctate structures are present, but they are composed only of PilA, while PilB is diffused in the cytoplasm and SurG is located in vacuoles and endosomes. Deletion of each of the genes does not lead to any obvious growth phenotype, except for moderate resistance to itraconazole. We could not find any obvious association between mycelial (PilA) eisosome-like structures and endocytosis. PilA and SurG are necessary for conidial eisosome organization in ways that differ from those for their S. cerevisiae homologues. These data illustrate that conservation of eisosomal proteins within the ascomycetes is accompanied by a striking functional divergence.

Formation and stability of eisosomes in the filamentous fungus Ashbya gossypii

“…in the germ bubble) and that eisosome biogenesis is either much reduced or restricted to a specific region in fast-growing hyphae. Also, mRNA levels of three genes encoding A. nidulans eisosomeassociated components are high in conidia and markedly decrease during germination (Vangelatos et al, 2010).…”

“…In a recent study about Aspergillus nidulans eisosomes, PilA and PilB, homologues of Pil1 and Lsp1, and SurG, one of several Sur7-like proteins, were investigated (Vangelatos et al, 2010). Interestingly, they colocalized as patches in the periphery of conidiospores, with SurG additionally found at perinuclear locations.…”

The Aspergillus nidulans Proline Permease as a Model for Understanding the Factors Determining Substrate Binding and Specificity of Fungal Amino Acid Transporters

“…The ϳ1500 bp 5Ј and 3Ј flanking sequences of gabA were PCR amplified using primers 1-8 of Table 2 digested with KpnI/XbaI and XbaI/NotI and subsequently cloned into a KpnI/NotI linearized pBlueScript II SK(ϩ)vector. In the unique XbaI site of the resulting plasmid, the AfpyrG gene, PCR amplified using primers 9 and 10 from plasmid p1439 (52,53) and XbaI digested was cloned. The resulting cassette was PCR amplified using primer pairs 1 and 4 and ϳ2 g of the products were used to transform strain nkuA⌬, selecting for uracil/uridine prototrophy.…”

Eisosome Ultrastructure and Evolution in Fungi, Microalgae, and Lichens

“…A recent review of fungal eisosomes (90) concludes: "Thus, we have a complex and strongly conserved cellular apparatus, which has even been called an organelle, without an obvious physiological function." Knockouts of eisosome-associated proteins in fungi generate a range of mutant phenotypes, from undetectable (33,35,90) to mild (14,16) to substantial (25,29,91,92). Douglas and Konopka (25) reviewed in detail the numerous functions that have been proposed for fungal eisosomes.…”

“…Walther et al (16) proposed the name eisosome (eis, Gr., into or portal) for the Pil1p/Lsp1p heteromer because their experiments indicated that it was associated with endocytosis, an interpretation that has since been challenged (29,(32)(33)(34)(35); but see reference 36). Formally, the full membrane/submembrane complex of yeast proteins should be denoted "MCC/eisosomes," and the invaginations should be denoted "furrows" (25).…”