title: The gene cutA of Fusarium fujikuroi, encoding a protein of the haloacid dehalogenase family, is involved in osmotic stress and glycerol metabolism.
abstract: Survival of micro-organisms in natural habitats depends on their ability to adapt to variations in osmotic conditions. We previously described the gene cut-1 of Neurospora crassa, encoding a protein of the haloacid dehalogenase family with an unknown function in the osmotic stress response. Here we report on the functional analysis of cutA, the orthologous gene in the phytopathogenic fungus Fusarium fujikuroi. cutA mRNA levels increased transiently after exposure to 0.68 M NaCl and were reduced upon return to normal osmotic conditions; deletion of the gene resulted in a partial reduction in tolerance to osmotic stress. ΔcutA mutants contained much lower intracellular levels of glycerol than the wild-type, and did not exhibit the increase following hyper-osmotic shock expected from the high osmolarity glycerol (HOG) response. cutA is linked and divergently transcribed with the putative glycerol dehydrogenase gene gldB, which showed the same regulation by osmotic shock. The intergenic cutA/gldB regulatory region contains putative stress-response elements conserved in other fungi, and both genes shared other regulatory features, such as induction by heat shock and by illumination. Photoinduction was also observed in the HOG response gene hogA, and was lost in mutants of the white collar gene wcoA. Previous data on glycerol production in Aspergillus spp. and features of the predicted CutA protein lead us to propose that F. fujikuroi produces glycerol from dihydroxyacetone, and that CutA is the enzyme involved in the synthesis of this precursor by dephosphorylation of dihydroxyacetone-3P.
authors.affiliation: Departamento of Genética, Facultad of Biología, Universidad de Sevilla, E-41012 Seville, Spain.
authors.forename: Jorge
authors.initials: J
authors.lastname: García-Martínez
authors.affiliation: Departamento of Genética, Facultad of Biología, Universidad de Sevilla, E-41012 Seville, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Castrillo
authors.affiliation: Departamento of Genética, Facultad of Biología, Universidad de Sevilla, E-41012 Seville, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Avalos
mesh_terms: D005670:Fusarium / Q000187:drug effects* / Q000235:genetics / Q000502:physiology*; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D023061:Gene Order; D005990:Glycerol / Q000378:metabolism*; D006867:Hydrolases / Q000235:genetics / Q000378:metabolism*; D009997:Osmotic Pressure; D012965:Sodium Chloride / Q000378:metabolism; D013312:Stress, Physiological
chemical_list: D012965:Sodium Chloride; D006867:Hydrolases; C034507:2-haloacid dehalogenase; D005990:Glycerol