The synthesis of Phosphate-repressible alkaline phosphatase do not appear to be regulated by ambient pH in the filamentous mould Neurospora crassa

Abstract

In order to investigate further the adaptive response of moulds to ambient pH, we have measured by ELISA the pho-2-encoded Pi-repressible alkaline phosphatase synthesised by Neurospora crassa. We showed that the 74A and pho-2A strains of this mould secrete similar amounts of the pho-2-encoded enzyme irrespective of ambient pH, when both the preg and pgov genes are not functional, i.e., in strains nuc-2 + growing under Pistarvation. This suggests that pho-2, which is responsive to Pi starvation via the action of genes nuc-2, preg, pgov and nuc-1, is not a gene responsive to ambient pH and that the differential glycosylation observed for the Pi-repressible alkaline phosphatase retained by the mycelium at pH 5.6 or secreted into the growth medium at pH 8.0 is the genetic response to ambient pH sensing in N. crassa.

The dermatophyte Trichophyton rubrum secretes an EDTA-sensitive alkaline phosphatase on high-phosphate medium

“…For example, acid and alkaline Pirepressible phosphatases are secreted into the growth medium at acid and alkaline pH, respectively (14,19). However, there is increasing evidence indicating that N. crassa secretes similar amounts of the pho-2-encoded Pi-repressible APase irrespective of ambient pH when wild-type strains grow in low-Pi medium, i.e., gene pho-2, which is responsive to Pi starvation via a hierarchical regulatory circuit (20), is not an alkaline gene. Interestingly, the synthesis and secretion of an APase is apparently nonresponsive to Pi starvation in the dermatophyte T. rubrum, since the synthesis and secretion of the APase occurs constitutively (Table 2).…”

Control of Acid Phosphatases Expression from Aspergillus niger by Soil Characteristics

“…Intracellular acid phosphatases have multiple functions involved in the utilisation of Pi (Pawar and Thaker 2009) in the metabolic process of fungus growth. The synthesis of these enzymes is controlled by the concentration of Pi and is regulated by the interactions of regulatory genes in N. crassa (Davis 2002;Nozawa et al 2002). It was concluded that the variation of Pi concentration in the soil could affect both the fungus growth and, in consequence, the production and secretion of phosphatases.…”

Influência do Gene pacC na Regulação de Manosiltransferases no Dermatófito Trichophyton rubrum em Função de Variações Nutricionais e pH Ambiente.

“…Em N. crassa, uma das respostas metabólicas em função do pH é a glicosilação de enzimas secretadas (Palma et al, 1989). Por exemplo, a fosfatase alcalina Pi-repressível codificada pelo gene pho-2 e sintetizada em pH alcalino difere da enzima sintetizada em pH ácido somente nos níveis de glicosilação, evidenciando a participação de glicosilações na resposta adaptativa ao pH (Nozawa et al, 2002).…”