The phospholipid flippase DnfD localizes to late Golgi and is involved in asexual differentiation in Aspergillus nidulans

ABSTRACT

The maintenance of cell shape requires finely tuned and robust vesicle trafficking in order to provide sufficient plasma membrane materials. The hyphal cells of filamentous fungi are an extreme example of cell shape maintenance due to their ability to grow rapidly and respond to the environment while keeping a relatively consistent shape. We have previously shown that two phospholipid flippases, which regulate the asymmetry of specific phospholipids within the plasma membrane, are important for hyphal growth in Aspergillus nidulans. Here, we examine the rest of the phospholipid flippases encoded by A. nidulans by obtaining single and double deletions of all four family members, dnfA, dnfB, dnfC, and dnfD. We find that deleting dnfC does not impart a noticeable phenotype, by itself or with other deletions, but that dnfD, the homolog of the essential yeast gene neo1, is important for conidiation. dnfD deletion mutants form misshapen conidiophore vesicles that are defective in metulae formation. We localize DnfD to late Golgi equivalents, where it appears just before dissociation of this organelle. We propose that DnfD functions in a trafficking process that is specifically required for the morphological changes that take place during conidiation.

KEYWORDS:

• Conidiation
• membrane
• morphogenesis
• polarity
• secretion

ACKNOWLEDGMENTS

We would like to thank Dr. Miguel Peñalva for generously sharing strains for this study.

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Funding

This work was supported by the National Science Foundation Graduate Research Fellowship under grant no. DGE-1252521 (ZSS), an East Asian Pacific Summer Institute (EAPSI) Fellowship grant (Z.S.S.), and TAMU CONACyT grant no. 2015-031 (B.D.S., R.M.P.).