Co-ordinate Regulation of Enzymes Involved in Ornithine Metabolism and its Relation to Sporophore Morphogenesis in Coprinus cinereus

Abstract

Arginine synthesis and urea formation via the ornithine cycle occurred in sporophore cap and stipe of Coprinus cinereus. Although urease was found at high activity in mycelium and stipe, it was not detectable in extracts of cap tissue, but arginine biosynthesis was specifically amplified during development of the cap as judged from metabolism of isotopically labelled substrates and increased enzyme activities. Four enzymes, NADP-linked glutamate dehydrogenase, glutamine synthetase, ornithine acetyltransferase and ornithine carbamoyltransferase, were considerably derepressed in developing caps while remaining low (or declining) in activity in the stipes supporting those caps. Co-ordinate regulation of these enzymes could also be demonstrated in vegetative mycelium subjected to particular synthetic growth media. Arginine, alanine and glutamate accumulated in the cap as a result of amplified arginine biosynthesis. A greater than twofold increase in the quantity of urea in the cap was also evident during development, although the concentration of urea remained essentially unchanged. A causal relationship between urea accumulation and water influx into developing cap tissues is suggested. The inflation of the gill hymenium cells accounts for the ' umbrella-like' cap expansion that characterizes Coprinus spp.

Expression of the urease gene of Agaricus bisporus: a tool for studying fruit body formation and post-harvest development

“…In C. cinereus, high urease activity in mycelium and stipe tissue was demonstrated but no detectable activity in cap tissue was found, which correlated with the accumulation of urea in cap tissues (Ewaze et al 1978). A causal relationship between urea accumulation and water influx into developing cap tissues was proposed, identical to the situation in A. bisporus.…”

Life History and Developmental Processes in the BasidiomyceteCoprinus cinereus

“…Trehalose and polyols have been excluded as the sole osmotic stabilizers, since the concentration of the former decreases during elongation whereas the latter are hardly present in stipes at all (141,142,338,406). Amino nitrogen compounds and urea have also been implicated in osmostabilization, but their contents are low and decline with development (123,142,344). Regularly in fruiting-body development, shortly before rapid stipe elongation, clear or sometimes yellowish droplets are excreted at the region where the cap with the gills is attached to the stipe (241; Kües, unpublished).…”

“…7]), the paraphyses expand from 3-4 m to 8 m, incorporate glycogen, vacuolize, and take on their characteristic rectangular shape. Inflation of paraphyses makes a major contribution to cap extension, which starts within the 1.5-h period between the ending of meiosis and the beginning of sterigma production (123,155,344,423). Basidia begin to form sterigmata and spores when they measure around 20 m (344, 394) (Fig.…”

Regulation of cyclic AMP-dependent phosphorylation of cellular proteins by the incompatibility factors in Coprinus cinereus.

“…It has been suggested that this enzyme also plays an important role in fruiting (20)(21)(22)(23). Although no significant difference in the level of glutamate dehydrogenase activity was observed between sexually-sterile and sexually-fertile strains, cAMPdependent inhibition of glutamate dehydrogenate activity was generally observed only in sexually-fertile strains and not in sterile strains.…”