Quantifying the importance of galactofuranose in Aspergillus nidulans hyphal wall surface organization by atomic force microscopy.

ABSTRACT: The fungal wall mediates cell-environment interactions. Galactofuranose (Galf), the five-member ring form of galactose, has a relatively low abundance in Aspergillus walls yet is important for fungal growth and fitness. Aspergillus nidulans strains deleted for Galf biosynthesis enzymes UgeA (UDP-glucose-4-epimerase) and UgmA (UDP-galactopyranose mutase) lacked immunolocalizable Galf, had growth and sporulation defects, and had abnormal wall architecture. We used atomic force microscopy and force spectroscopy to image and quantify cell wall viscoelasticity and surface adhesion of ugeA? and ugmA? strains. We compared the results for ugeA? and ugmA? strains with the results for a wild-type strain (AAE1) and the ugeB deletion strain, which has wild-type growth and sporulation. Our results suggest that UgeA and UgmA are important for cell wall surface subunit organization and wall viscoelasticity. The ugeA? and ugmA? strains had significantly larger surface subunits and lower cell wall viscoelastic moduli than those of AAE1 or ugeB? hyphae. Double deletion strains (ugeA? ugeB? and ugeA? ugmA?) had more-disorganized surface subunits than single deletion strains. Changes in wall surface structure correlated with changes in its viscoelastic modulus for both fixed and living hyphae. Wild-type walls had the largest viscoelastic modulus, while the walls of the double deletion strains had the smallest. The ugmA? strain and particularly the ugeA? ugmA? double deletion strain were more adhesive to hydrophilic surfaces than the wild type, consistent with changes in wall viscoelasticity and surface organization. We propose that Galf is necessary for full maturation of A. nidulans walls during hyphal extension.

SUBMITTER: Paul BC 

PROVIDER: S-EPMC3127658 | biostudies-literature | 2011 May

REPOSITORIES: biostudies-literature