Phosphatidylinositol-4-phosphate-dependent membrane traffic is critical for fungal filamentous growth

Abstract

The phospholipid phosphatidylinositol-4-phosphate [PI(4)P], generated at the Golgi and plasma membrane, has been implicated in many processes, including membrane traffic, yet its role in cell morphology changes, such as the budding to filamentous growth transition, is unknown. We show that Golgi PI(4)P is required for such a transition in the human pathogenic fungus Candida albicans. Quantitative analyses of membrane traffic revealed that PI(4)P is required for late Golgi and secretory vesicle dynamics and targeting and, as a result, is important for the distribution of a multidrug transporter and hence sensitivity to antifungal drugs. We also observed that plasma membrane PI(4)P, which we show is functionally distinct from Golgi PI(4)P, forms a steep gradient concomitant with filamentous growth, despite uniform plasma membrane PI-4-kinase distribution. Mathematical modeling indicates that local PI(4)P generation and hydrolysis by phosphatases are crucial for this gradient. We conclude that PI(4)P-regulated membrane dynamics are critical for morphology changes.

On‐site secretory vesicle delivery drives filamentous growth in the fungal pathogenCandida albicans

“…Our results demonstrate that GFP-Sec4 is distributed in three distinct regions along the hyphal filament: in agreement with previous studies (Ghugtyal et al, 2015;Jones & Sudbery, 2010), Sec4 is predominantly localised to the Spk (Segment 10, 0.41 ± 0.10 total signal) and is also present on vesicles along the entire length of the hyphal filament (Segments 1-7, 0.40 ± 0.15 total signal). Our results demonstrate that GFP-Sec4 is distributed in three distinct regions along the hyphal filament: in agreement with previous studies (Ghugtyal et al, 2015;Jones & Sudbery, 2010), Sec4 is predominantly localised to the Spk (Segment 10, 0.41 ± 0.10 total signal) and is also present on vesicles along the entire length of the hyphal filament (Segments 1-7, 0.40 ± 0.15 total signal).…”

“…Furthermore, the presence of SVs found in close association with elongated membranes at the hyphal tip ( Figure 2g) may be indicative of SV budding events. We hypothesised that these elongated membranes could be part of the ER or the Golgi, as these compartments were previously observed in C. albicans filamentous cells using fluorescent microscopy (Ghugtyal et al, 2015;Rida et al, 2006). Examination of the 3D membrane organisation in (Preuss, Mulholland, Franzusoff, Segev, & Botstein, 1992), and also resembles Golgi in other filamentous fungi (Pantazopoulou, 2016).…”

“…The process of C. albicans polarised growth presents several common features with filamentous fungi: the presence of a Spk, endocytosis via actin patches located sub-apically (Berepiki, Lichius, & Read, 2011;Caballero-Lima et al, 2013;Ghugtyal et al, 2015;Martin et al, 2007), scattered (nonstacked) Golgi cisternae (Harris, 2013;Rida, Nishikawa, Won, & Dean, 2006) and the requirement for intact actin cables required for motor mediated trafficking of cargo and membranes towards the apex (Berepiki et al, 2011;Crampin et al, 2005;Jones & Sudbery, 2010). It is therefore generally assumed that the principles of polarised growth in C. albicans are similar to those found in filamentous fungi such as N. crassa and A. nidulans.…”

Plasma membrane organization promotes virulence of the human fungal pathogen Candida albicans

“…PI 4,5 P 2 is known to promote polarized cell growth by recruiting morphogenesis proteins to the plasma membrane. PI 4 P, which is involved in vesicle trafficking and membrane dynamics, is also enriched at hyphal tips (Ghugtyal, et al ., 2015). In addition, regulation of sphingolipid synthesis plays an important role as cells lacking the Lag1 ceramide synthase, which are defective in forming inositol-containing sphingolipids, fail to form hyphae (Cheon, et al ., 2012).…”

“…Proteins involved in sensing extracellular pH (Rim9, Dfg16, and Rim21) were similarly found in patches that were independent of eisosomes (Obara, et al ., 2012). Although the role of clustering these proteins into patches is not clear, it is significant that the proteins in these complexes are important for viability or virulence of C. albicans (Davis, 2009, Ghugtyal, et al ., 2015). …”