Presentation Information
[P02-171]Identification of regulators of septal pore-mediated cell-to-cell connectivity in filamentous fungi by protein-protein interaction screening.
○Chikashi Tagami1, Yuya Hamanaka1, Misa Kuroki1, Thuc Bui2, Ozgur Bayram2, Jun-ichi Maruyama1,3 (1. Dept. of Biotechnol., The Univ. of Tokyo (Japan), 2. Dept. of Biol., Maynooth Univ. (Ireland), 3. CRIIM, The Univ. of Tokyo (Japan))
Keywords:
Aspergillus oryzae,septal pore,cell-to-cell connectivity,transglutaminase,endocytosis
Filamentous fungi are multicellular organisms in which septal pores serve as cytoplasmic channels enabling cell-to-cell connectivity, analogous to animal gap junction and plant plasmodesmata. Through a large-scale screening in the filamentous fungus Aspergillus oryzae, we identified 23 proteins involved in regulating septal pore-mediated connectivity [1].
Among these, we focused on SppB, a transglutaminase domain-containing protein that accumulates to the septal pore and prevents excessive cytoplasmic loss upon hyphal wounding. Given that transglutaminases are cross-linking enzymes, the enzymatic activity of SppB is likely to mediate its protective function at the septal pore [2].
To further elucidate the underlying mechanism, we identified candidate SppB-interacting proteins and functionally analyzed two A. oryzae amphiphysin orthologs, AoRvs167 and AoRvs161, corresponding to Rvs167/161 in the yeast Saccharomyces cerevisiae. Both proteins accumulated to the septal pore upon hyphal wounding, and deletions exhibited an impaired ability to prevent the excessive cytoplasmic loss at the septal pore, phenocopying the defects observed in the sppB deletion. Furthermore, localization and functional analyses in the sppB deletion background suggest that these proteins act in a coordinated manner to regulate the septal pore function and maintain cell-to-cell connectivity, potentially involving an endocytosis-related membrane remodeling mechanism.
[1] Mamun, et al. (2023) Nat. Commun.
[2] Mamun, et al. (2023) Mol. Biol. Cell
Among these, we focused on SppB, a transglutaminase domain-containing protein that accumulates to the septal pore and prevents excessive cytoplasmic loss upon hyphal wounding. Given that transglutaminases are cross-linking enzymes, the enzymatic activity of SppB is likely to mediate its protective function at the septal pore [2].
To further elucidate the underlying mechanism, we identified candidate SppB-interacting proteins and functionally analyzed two A. oryzae amphiphysin orthologs, AoRvs167 and AoRvs161, corresponding to Rvs167/161 in the yeast Saccharomyces cerevisiae. Both proteins accumulated to the septal pore upon hyphal wounding, and deletions exhibited an impaired ability to prevent the excessive cytoplasmic loss at the septal pore, phenocopying the defects observed in the sppB deletion. Furthermore, localization and functional analyses in the sppB deletion background suggest that these proteins act in a coordinated manner to regulate the septal pore function and maintain cell-to-cell connectivity, potentially involving an endocytosis-related membrane remodeling mechanism.
[1] Mamun, et al. (2023) Nat. Commun.
[2] Mamun, et al. (2023) Mol. Biol. Cell
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