title: Mapping of the nitrate-assimilation gene cluster (crnA-niiA-niaD) and characterization of the nitrite reductase gene (niiA) in the opportunistic fungal pathogen Aspergillus fumigatus.
abstract: This study reports the molecular characterization of the nitrate-assimilation gene cluster from the opportunistic fungal pathogen Aspergillus fumigatus. A genomic fragment was isolated which contained the entire structural gene encoding nitrite reductase (niiA), plus segments of the nitrate reductase (niaD) and the nitrate transporter (crnA) genes. Nitrate-assimilation genes in A. fumigatus are physically linked and transcribed in the same direction as in A. nidulans. The nitrate-assimilation gene cluster is on the largest chromosome (5.3 Mb). The nitrite reductase (niiA) gene encodes a protein of 1110 amino acids that contains regions corresponding to FAD, NADPH, FeS and siroheme binding sites. Eight small introns interrupt the niiA open reading frame. The niaD-niiA intergenic regulatory region contains promoter consensus sequences including TATA, CAAT, and binding sites for the areA and nirA gene products. Northern analysis indicated that the expression of niaD, niiA and crnA are induced by nitrate and repressed by ammonium at the transcriptional level.
authors.affiliation: Department of Biological Sciences, Simon Fraser University, Burnaby, BC V5A 1S6, Canada.
authors.forename: Y G
authors.initials: YG
authors.lastname: Amaar
authors.forename: M M
authors.initials: MM
authors.lastname: Moore
mesh_terms: D000595:Amino Acid Sequence; D027321:Anion Transport Proteins; D001232:Aspergillus fumigatus / Q000201:enzymology / Q000235:genetics*; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics; D002874:Chromosome Mapping; D015825:Chromosomes, Fungal / Q000235:genetics; D003001:Cloning, Molecular; D005656:Fungal Proteins; D015966:Gene Expression Regulation, Fungal / Q000502:physiology; D005800:Genes, Fungal / Q000235:genetics*; D007438:Introns / Q000235:genetics; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics*; D050901:Nitrate Reductase; D009565:Nitrate Reductases / Q000235:genetics; D000091285:Nitrate Transporters; D009566:Nitrates / Q000378:metabolism; D009572:Nitrite Reductases / Q000235:genetics*; D012331:RNA, Fungal / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D015183:Restriction Mapping; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
chemical_list: D027321:Anion Transport Proteins; D002352:Carrier Proteins; D005656:Fungal Proteins; D000091285:Nitrate Transporters; D009566:Nitrates; D012331:RNA, Fungal; D012333:RNA, Messenger; D009565:Nitrate Reductases; D009572:Nitrite Reductases; D050901:Nitrate Reductase