Galactofuranose (Galf), the five-member ring form of galactose, is a minor component of Aspergillus walls. Strains deleted for Galf biosynthesis enzymes UgeA (UDP-glucose-4-epimerase) and UgmA (UDP-galactopyranose mutase) lacked immunolocalizable Galf, and had growth defects and abnormal wall structure. We used atomic force microscopy and force spectroscopy to image and quantify surface elasticity and adhesion of ugeA) and ugmA) strains and to compare them with two near-isogenic wild type strains, AAE1 and ugeB). Our results suggest that UgeA and UgmA are important for cell wall surface subunit organization and wall elasticity. The ugeA) and ugmA) strains had larger surface subunits and lower cell wall viscoelasticity than those of AAE1 or ugeB) hyphae. Double deletion strains [ugeA), ugeB)] and [ugeA), ugmA)] had more disorganized surfaces than single deletion strains. Wall surface structure correlated with wall viscoelasticity for both fixed and living hyphae, with wild type walls being the most viscoelastic and the double deletion strains being the least. The ugmA) and particularly the [ugeA), ugmA)] strain were more adhesive to hydrophilic surfaces than wild type. We propose that Galf is necessary for proper packing of cell wall components, so its loss gives rise to surface disorder, greater hydrophilic character and reduced viscoelasticity.
Full conference title:
26th Fungal Genetics Conference
- Fungal Genetics Conference 26th (2005)