Production and composition of an exocellular Nigeran-protein complex isolated from cultures of Aspergillus awamori.

AUTOR(ES)

Bobbitt, T F

RESUMO

Aspergillus awamori Nakazawa (QM873) hyphae maintained on a nitrogen-deficient medium produced an exocellular complex consisting of the wall alpha-glucan, nigeran (94%), water-soluble nigeran oligosacchrides (1 to 2%), protein (2 to 4%), and a small amount of beta-glycan (less than 1%). Nigeran was not covalently linked to protein. The complex appeared in the growth medium only under those temporal or nutritional conditions where the hyphal wall content to nigeran reached at least 30% of the cell dry weight. Rates of nigeran accumulation in the hypha cell wall, scanning electron microscopy of hyphae, and pulse-chase experiments with [14C]glucose suggested that the complex arises via displacement of a portion of the hyphal wall into the medium. The nigeran portion of the complex contained lamellar crystalline domains similar to those in the intact cell wall. Enzymic digestion of nigeran in the complex indicated that it has a degree of crystallinity lower than that observed with pure nigeran crystals grown in vitro. Therefore, polymerization in vivo resulted in somewhat less chain organization in the crystallite. Since this complex was isolated without any prior chemical or exogenous enzymatic treatment, it should be useful for studies of hyphal wall biogenesis and organization in this organism.

Documentos Relacionados

• Distribution and conformation of crystalline nigeran in hyphal walls of Aspergillus niger and Aspergillus awamori.
• Complete genomic sequence encoding trpC from Aspergillus niger var. awamori.
• Molecular cloning and characterization of the glucoamylase gene of Aspergillus awamori.
• Analysis of heterologous protein production in defined recombinant Aspergillus awamori strains.
• Kinetics of mRNA and protein synthesis of genes controlled by the 1,4-beta-endoxylanase A promoter in controlled fermentations of Aspergillus awamori.