title: Transcription levels of CHS5 and CHS4 genes in Paracoccidioides brasiliensis mycelial phase, respond to alterations in external osmolarity, oxidative stress and glucose concentration.
abstract: The complete sequence of Paracoccidioides brasiliensis CHS5 gene, encoding a putative chitin synthase revealed a 5583nt open reading frame, interrupted by three introns of 82, 87 and 97bp (GenBank Accession No EF654132). The deduced protein contains 1861 amino acids with a predicted molecular weight of 206.9kDa. Both its large size and the presence of a N-terminal region of approx. 800 residues with a characteristic putative myosin motor-like domain, allow us to include PbrChs5 into class V fungal chitin synthases. Sequence analysis of over 4kb from the 5' UTR region in CHS5, revealed the presence of a previously reported CHS4 gene in P. brasiliensis, arranged in a head-to-head configuration with CHS5. A motif search in this shared region showed the presence of stress response elements (STREs), three binding sites for the transcription activators Rlm1p (known to be stimulated by hypo-osmotic stress) and clusters of Adr1 (related to glucose repression). A quantitative RT-PCR analysis pointed to changes in transcription levels for both genes following oxidative stress, alteration of external osmolarity and under glucose-repressible conditions, suggesting a common regulatory mechanism of transcription.
authors.affiliation: Instituto Venezolano de Investigaciones Científicas, Centro de Microbiología y Biología Celular, Apartado 20632, Caracas 1020A, Venezuela. gnino@ivic.ve
authors.forename: Gustavo A
authors.initials: GA
authors.lastname: Niño-Vega
authors.forename: Françoise
authors.initials: F
authors.lastname: Sorais
authors.forename: Gioconda
authors.initials: G
authors.lastname: San-Blas
mesh_terms: D020816:Amino Acid Motifs; D002687:Chitin Synthase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D015966:Gene Expression Regulation, Fungal; D005947:Glucose / Q000235:genetics; D025282:Mycelium / Q000737:chemistry / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D009994:Osmolar Concentration; D018384:Oxidative Stress; D010228:Paracoccidioides / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D014158:Transcription, Genetic
chemical_list: D005656:Fungal Proteins; D002687:Chitin Synthase; D005947:Glucose