title: DhARO4, an amino acid biosynthetic gene, is stimulated by high salinity in Debaryomyces hansenii.
abstract: The highly halotolerant yeast Debaryomyces hansenii when grown in the presence of 2M NaCl, increased the expression of ARO4 which is involved in the biosynthesis of aromatic amino acids. The function of the isolated gene was verified by complementation of a Saccharomyces cerevisiae null mutant, aro4Delta, restoring the specific activity of the enzyme (a 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase) to wild-type levels. DhARO4 transcript expression under high salinity was stimulated at the beginning of the exponential growth phase. As the DhARO4 promoter region presents putative GCRE and CRE sequences, its expression was evaluated under conditions of NaCl stress and amino acid starvation, showing similar expression levels for either condition. The combined effect of both stressors resulted in a further increase in transcript levels over the singly added stressors, indicating independent stimulatory events. Our results support the hypothesis that high salinity and amino acid availability are physiologically interconnected.
authors.affiliation: Unidad Académica Puerto Morelos, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Apartado Postal 1152, Cancún, Quintana Roo 77500, México. marissa@mar.icmyl.unam.mx
authors.forename: Marissa
authors.initials: M
authors.lastname: Calderón-Torres
authors.forename: Antonio
authors.initials: A
authors.lastname: Peña
authors.forename: Patricia E
authors.initials: PE
authors.lastname: Thomé
mesh_terms: D010723:3-Deoxy-7-Phosphoheptulonate Synthase / Q000235:genetics* / Q000378:metabolism*; D024322:Amino Acids, Aromatic / Q000096:biosynthesis*; D015152:Blotting, Northern; D004926:Escherichia coli / Q000235:genetics; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D005816:Genetic Complementation Test; D012331:RNA, Fungal / Q000737:chemistry / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D004718:Saccharomycetales / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology
chemical_list: D024322:Amino Acids, Aromatic; D012331:RNA, Fungal; D012965:Sodium Chloride; D010723:3-Deoxy-7-Phosphoheptulonate Synthase