title: Ambient pH sensing in filamentous fungi: pitfalls in elucidating regulatory hierarchical signaling networks.
abstract: In this article, the experiments used to construct the ambient pH-signaling network involved in the secretion of enzymes by filamentous fungi have been reviewed, focusing on the phosphate-repressible phosphatases in Aspergillus nidulans. Classic and molecular genetics have been used to demonstrate that proteolysis of the transcription factor PacC at alkaline ambient pH is imperative for its action, implying that the full-length version is not an active molecular form of PacC. It has been hypothesized that the transcriptional regulator PacC may be functional at both acidic and alkaline ambient pH, in either the full-length or the proteolyzed form, if it carries a pal-dependent molecular tag. The products of the pal genes are involved in a metabolic pathway that led to the synthesis of effector molecules that tag the pacC product, perhaps facilitating its proteolysis.
authors.affiliation: Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil.
authors.forename: Antonio
authors.initials: A
authors.lastname: Rossi
authors.forename: Aline H S
authors.initials: AH
authors.lastname: Cruz
authors.forename: Rodrigo S
authors.initials: RS
authors.lastname: Santos
authors.forename: Patrícia M
authors.initials: PM
authors.lastname: Silva
authors.forename: Emiliana M
authors.initials: EM
authors.lastname: Silva
authors.forename: Niege S
authors.initials: NS
authors.lastname: Mendes
authors.forename: Nilce M
authors.initials: NM
authors.lastname: Martinez-Rossi
mesh_terms: D001233:Aspergillus nidulans / Q000201:enzymology* / Q000235:genetics; D005656:Fungal Proteins / Q000378:metabolism / Q000502:physiology*; D015966:Gene Expression Regulation, Fungal; D006863:Hydrogen-Ion Concentration; D008954:Models, Biological; D008956:Models, Chemical; D010710:Phosphates / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*
chemical_list: D005656:Fungal Proteins; C092394:PacC protein, Aspergillus; D010710:Phosphates; D014157:Transcription Factors; D010744:Phosphoric Monoester Hydrolases
keywords: PacC activation; Pi-repressible phosphatases; acid phosphatase; alkaline phosphatase; pH regulation; pacC gene; pal genes; phosphate sensing