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

Abstract

The phosphorylation of a cellular protein of 46,000 daltons was stimulated by the addition of adenosine 3',5'-cyclic monophosphate (cAMP) in the sexually fertile dikaryotic and Amut Bmut strains of Coprinus cinereus, but not in the sexually sterile Amut, Bmut, and wild-type monokaryons. Cyclic AMP-dependent inhibition of glutamate dehydrogenase was observed only in the dikaryotic and Amut Bmut strains, but not in the Amut, Bmut, and monokaryotic strains.Extremely low levels of ATP and cAMP were sufficient to bring about half maximal inactivation of glutamate dehydrogenase.The results indicate that glutamate dehydrogenase is an endogenous substrate for cAMP-dependent protein kinase which is regulated by the incompatibility factors.In eukaryotic organisms including several fungi, adenosine 3',5'-cyclic monophosphate (cAMP) was found to exert its effects through the activation of cAMPdependent protein kinase which then governed the action of several proteins including key metabolic enzymes through phosphorylation (1-5). In Coprinus cinereus as in other eukaryotes, the regulatory subunit of cAMP-dependent protein kinase was found to be the receptor of cAMP (6). Also in relation to previous observations that a high level of cAMP correlated with fruiting ability (7-10), a high level of cAMP-dependent protein kinase activity was reported to be correlated with fruiting ability (6).Sexual morphogenesis in the tetrapolar basidiomycetes is known to be triggered by the switching `on' of both A-and B-factor controlled events. In C. cineretts, mutants of A and B incompatibility factors (Amut and Bmut) have been isolated (11-13). These Amut and Bmut mutations led to constitutive expression of events regulated by the respective incompatibility factor and resulted in the conversion of self-incompatible strains to self-compatible ones (13). It was thus hoped 339

Mating Type in Filamentous Fungi

“…Perhaps phosphorylation by PKA influences the activity of proteins whose expression is regulated by mating-type proteins. Certainly, evidence has been presented for a connection between A factor regulation and PKA phosphorylation of a specific protein in C. cinereus (106). In addition, cAMP stimulates fruiting body formation in S. commune and C. cinereus (86).…”

Life History and Developmental Processes in the BasidiomyceteCoprinus cinereus

“…Although A and B mating-type genes regulate distinct cellular functions (see above), in the dikaryon they coordinately control functions such as cyclic AMP (cAMP) production, cAMP-dependent protein kinase activity (453,454), repression of oidiation (232), and, as suggested previously for Amut Bmut homokaryons (265,452) and now shown in A and B activated transformants, also fruiting-body initiation (240a). Strikingly, all these functions are also light regulated (203,232,277,350,351,492).…”

“…There are, however, considerable differences in the way these factors are linked in regulation. For cAMP production and cAMP-dependent protein kinase activity, both mating-type pathways have to be active and light has a stimulatory effect (453,454,492). In fruiting-body initiation, where light is usually required (350, 351) (see above), activation of the A pathway can be sufficient (258,261,459) but additional activation of the B mating-type pathway clearly promotes fruiting when light signals are provided (240a, 459; Kües, unpublished).…”

Molecular Mechanisms Involved in the Multicellular Growth of Ustilaginomycetes

“…In the early developmental stages of U. maydis basidiocarps (a complex multicellular structure), the gene encoding the cAMP-dependent protein kinase catalytic subunit was 2.3 times overexpressed [ 41 ]. In this regard, in C. cinerea , Schizophyllum commune and Volvariella volvacea , the cAMP content is essential for the formation of the fruiting body [ 108 , 109 , 110 , 111 ], and the genes of cAMP/PKA signaling pathways are up-regulated during the development of the C. cinerea fruiting body [ 96 ]. Finally, the participation of the kinase A protein and cAMP-dependent protein kinase in the formation of S. reilianum multicellular clusters was predicted by transcriptional network analyses [ 13 ].…”