Isolation and analysis of fungal phosphorylated proteoglycan

Abstract

1978) Isolation and analysis of fungal phosphorylated proteoglycan. Can. J. Biochem. 56,[237][238][239][240][241][242][243][244][245] A low molecular-weight phosphorylated proteoglycan (PPG) was isolated from the freshwater fungus Achlya by cold osmotic-shock treatment of newly germinated spores and purified. PPG contained 38.5% carbohydrate (89% glucose), 33% protein, and 28.5% phosphate. There was the equivalent of one uracil base in the form of uridylate per PPG molecule. The molecular weight estimations by Sephadex G-50 bead filtration, electrophoresis, and chemical analysis were in agreement. The values varied from 6000-7000. Most of the amino acids (21 residues) were D-optical isomers. All of the glucose molecules were in phosphodiester linkage as acid hydrolysis of PPG yielded mainly glucose-6-phosphate, some free glucose, and P,. PPG, therefore, may be a sugar-phosphate polymer with peptides attached at one or more sites. The uracil moiety is covalently attached to the PPG probably as UDPG.Loosely associated with the PPG were three polyphosphorylated dinucleosides, HS3, HS2, and HSI, which were easily displaced when the PPG was filtered through a Sephadex G-50 column. Neither Mg(I1) nor Ca(I1) could stabilize the association. Hg(II), Ag(I), and KI altered the uv-absorption spectra of HS compounds and HS-free PPG in an identical manner. This was attributed to the uracil derivative present in all HS compounds and PPG. Similar changes were shown with authentic UDPG, UDP, and UMP, not uridine, when they complexed with Hg(II), Ag(I), and KI.Both PPG and(or) HS compounds may play an essential role in cell growth as their removal by osmotic shock arrested further development until they were relaid in the cell wall membrane complex. We suggest that PPG may have a function(s) similar to those assigned to teichoic acids and sugar-phosphate polymers of bacteria. Cameron, L. E. & LeJohn, H. B. (1978) Isolation and analysis of fungal phosphorylated proteoglycan. Can. J. Biochem. 56, 237-245Par traitement osmotique a froid des spores nouvellement germees du champignon Achlya, nous avons isole un proteoglycan phosphoryle (PPG), de faible poids moleculaire et nous l'avons purifie. Le PPG contient 38.5% de glucide (89% de glucose), 33% de proteine et 28.5% de phosphate. Chaque molecule de PPG contient l'equivalent d'une base uracile sous forme d'uridylate. Les valeurs du poids moleculaire evalue par filtration sur Sephadex G-50, par electrophorese et par analyse chimique concordent. Ces valeurs varient de 6000 a 7000. La plupart des acides amines (21 residus) sont des isomeres optiques D. Toutes les molecules de glucose sont en liaison phosphodiester, puisque l'hydrolyse acide du PPG donne surtout du glucose-6-phosphate, une certaine quantite de glucose libre et du Pi. Le PPG peut donc etre un polymere phosphoglucidique avec des peptides attaches a un ou plusieurs sites. La portion uracile est liee de f a~o n covalente au PPG, probablement sous forme d'UDPG.Faiblement associes au PPG, nous retrouvons trois dinucleosides p...