PT  - JOURNAL ARTICLE
AU  - Berit Hassing
AU  - Alyesha Candy
AU  - Carla J. Eaton
AU  - Tania R. Fernandes
AU  - Carl H. Mesarich
AU  - Antonio Di Pietro
AU  - Barry Scott
TI  - A homologue of the mammalian tumour suppressor protein PTEN is a functional lipid phosphatase and required for chemotaxis in filamentous fungi
AID  - 10.1101/2020.09.15.298703
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.09.15.298703
4099  - http://biorxiv.org/content/early/2020/09/16/2020.09.15.298703.short
4100  - http://biorxiv.org/content/early/2020/09/16/2020.09.15.298703.full
AB  - Phosphoinositides (PI) are essential components of eukaryotic membranes and function in a large number of signalling processes. While lipid second messengers are well studied in mammals and yeast, their role in filamentous fungi is poorly understood. We used fluorescent PI-binding molecular probes to localise the phosphorylated phosphatidylinositol species PI[3]P, PI[3,5]P2, PI[4]P and PI[4,5]P2 in hyphae of the endophyte Epichloë festucae in axenic culture and during interaction with its grass host Lolium perenne. We also analysed the roles of the phosphatidylinositol-4-phosphate 5-kinase MssD and the predicted phosphatidylinositol-3,4,5-triphosphate 3-phosphatase TepA, a homologue of the mammalian tumour suppressor protein PTEN. Deletion of tepA in E. festucae and in the root-infecting tomato pathogen Fusarium oxysporum had no impact on growth in culture or the host interaction phenotype. However, this mutation did uncover the presence of PI[3,4,5]P3 in septa of E. festucae and showed that TepA is required for chemotropism in F. oxysporum. The identification of PI[3,4,5]P3 in septa of ΔtepA strains suggests that filamentous fungi are able to generate PI[3,4,5]P3 using an alternative biosynthetic pathway and that fungal PTEN homologues are functional lipid phosphatases. The F. oxysporum chemotropism defect demonstrates a conserved role of PTEN homologues in chemotaxis across protists, fungi and mammals.Competing Interest StatementThe authors have declared no competing interest.