Induction of Cellular Efflux by a Galactosamine Polymer from Neurospora crassa

Abstract

A cationic polymer of D-galactosamine was isolated from culture filtrates of a colonial temperature-sensitive strain of Neurospora crassa. Adsorption of the polymer to the cell surface initiated immediate efflux of low molecular weight metabolites and subsequent loss of viability. The polymer appeared to bind to those sites on the cell surface that normally bind calcium ions. Chemical analysis of the polymer showed it to be partially N-acetylated. The polymer had an isoelectric point of 8.4. Thirty percent of the D-galactosamine residues contained free amino groups. A rapid assay that has potential application for monitoring the effect of a variety of other membrane-active factors on membrane permeability has been developed.

Structural and biochemical characterization of the exopolysaccharide deacetylase Agd3 required for Aspergillus fumigatus biofilm formation

“…The degree of deacetylation of A. fumigatus GAG is not known, however, analysis of the GAG from Neurospora crassa found that the polymer has between 30 and 70% deacetylated galactosamine depending on the growth conditions. In N. crassa, deacetylation was correlated with the level of expression of a deacetylase [39][40][41] . Recently, it was shown that Aspergillus oryzae produces GAG with a degree of deacetylation near 50% 42 .…”