title: A catalytic subunit of cyclic AMP-dependent protein kinase, PKAC-1, regulates asexual differentiation in Neurospora crassa.
abstract: A cyclic AMP (cAMP)-dependent protein kinase pathway has been shown to regulate growth, morphogenesis and virulence in filamentous fungi. However, the precise mechanisms of regulation through the pathway remain poorly understood. In Neurospora crassa, the cr-1 adenylate cyclase mutant exhibits colonial growth with short aerial hyphae bearing conidia, and the mcb mutant, a mutant of the regulatory subunit of cAMP-dependent protein kinase (PKA), shows the loss of growth polarity at the restrictive temperature. In the present study, we isolated mutants of the catalytic subunit of the PKA gene pkac-1 through the process of repeat-induced point mutation (RIP). PKA activity of the mutants obtained through RIP was undetectable. The genome sequence predicts two distinct catalytic subunit genes of PKA, named pkac-1 (NCU06240.1, AAF75276) and pkac-2 (NCU00682.1), as is the case in most filamentous fungi. The results suggest that PKAC-1 works as the major PKA in N. crassa. The phenotype of the pkac-1 mutants included colonial growth, short aerial hyphae, premature conidiation on solid medium, inappropriate conidiation in submerged culture, and increased thermotolerance. This phenotype of pkac-1 mutants resembled to that of cr-1 mutants, except that the addition of cAMP did not rescue the abnormal morphology of pkac-1 mutants. The loss of growth polarity at the restrictive temperature in the mcb mutant was suppressed by pkac-1 mutation. These results suggest that the signal transduction pathway mediated by PKAC-1 plays an important role in regulation of aerial hyphae formation, conidiation, and hyphal growth with polarity.
authors.affiliation: Faculty of Life Sciences, Toyo University, Gunma, Japan.
authors.forename: Shinpei
authors.initials: S
authors.lastname: Banno
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Ochiai
authors.forename: Rieko
authors.initials: R
authors.lastname: Noguchi
authors.forename: Makoto
authors.initials: M
authors.lastname: Kimura
authors.forename: Isamu
authors.initials: I
authors.lastname: Yamaguchi
authors.forename: Sei-ichi
authors.initials: S
authors.lastname: Kanzaki
authors.forename: Tadako
authors.initials: T
authors.lastname: Murayama
authors.forename: Makoto
authors.initials: M
authors.lastname: Fujimura
mesh_terms: D020134:Catalytic Domain / Q000235:genetics / Q000502:physiology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D009024:Morphogenesis / Q000235:genetics / Q000502:physiology*; D009154:Mutation; D009492:Neurospora crassa / Q000235:genetics / Q000254:growth & development*; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology
chemical_list: D005656:Fungal Proteins; D017868:Cyclic AMP-Dependent Protein Kinases