Morphogenetic and developmental functions of the Aspergillus nidulans homologues of the yeast bud site selection proteins Bud4 and Axl2

Haoyu Si, William R. Rittenour, Kaimei Xu, Mark Nicksarlian, Ana M. Calvo, Steven D. Harris

Research output: Contribution to journalArticle

22 Scopus citations

Abstract

The yeast bud site selection system represents a paradigm for understanding how fungal cells regulate the formation of a polarity axis. In Saccharomyces cerevisiae, Bud4 and Axl2 are components of the axial bud site marker. To address the possibility that these proteins regulate cellular morphogenesis in filamentous fungi, we have characterized homologues of Bud4 and Axl2 in Aspergillus nidulans. Our results show that Bud4 is involved in septum formation in both hyphae and developing conidiophores. Whereas Axl2 appears to have no obvious role in hyphal growth, it is required for the regulation of phialide morphogenesis during conidiation. In particular, Axl2 localizes to the phialide-spore junction, where it appears to promote the recruitment of septins. Furthermore, the developmental regulators BrlA and AbaA control the expression of Axl2. Additional studies indicate that Axl2 is also involved in the regulation of sexual development, not only in A. nidulans, but also in the phylogenetically unrelated fungus Fusarium graminearum. Our results suggest that Axl2 plays a key role in phialide morphogenesis and/or function during conidiation in the aspergilli.

Original languageEnglish (US)
Pages (from-to)252-270
Number of pages19
JournalMolecular Microbiology
Volume85
Issue number2
DOIs
StatePublished - Jul 2012

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology

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