Characterization of the Aspergillus parasiticus niaD and niiA gene cluster.
The nitrate reductase gene (niaD) and nitrite reductase gene (niiA) of Aspergillus parasiticus are clustered and are divergently transcribed from a 1.6-kb intergenic region (niaD-niiA). The deduced aminoacid sequence of the A. parasiticus nitrate reductase demonstrated a high degree of homology to those of other Aspergillus species, as well as to Leptosphaeria maculans, Fusarium oxysporum, Gibberella fujikuroi and Neurospora crassa, particularly in the cofactor-binding domains for molybdenum, heme and FAD. A portion of the deduced nitrite reductase sequence was homologous to those of A. nidulans and N. crassa. The nucleotide sequences in niaD-niiA of A. parasiticus and of A. oryzae were 95% identical, indicating that these two species are closely related. Several GATA motifs, the recognition sites for the N. crassa positive-acting global regulatory protein NIT2 in nitrogen metabolism, were found in A. parasiticus niaD-niiA. Two copies of the palindrome TCCGCGGA and other partial palindromic sequences similar to the target sites for the pathway specific regulatory proteins, N. crassa NIT4 and A. nidulans NirA, in nitrate assimilation, were also identified. A recombinant protein containing the A. nidulans AreA (the NIT2 equivalent) zinc finger and an adjacent basic region was able to bind to segments of niaD-niiA encompassing the GATA motifs. These results suggest that the catalytic and regulatory mechanisms of nitrate assimilation are well conserved in Aspergillus.
Chang
P K
PK
Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118, USA.
Ehrlich
K C
KC
Linz
J E
JE
Bhatnagar
D
D
Cleveland
T E
TE
Bennett
J W
JW
D000595:Amino Acid Sequence; D001230:Aspergillus / Q000201:enzymology* / Q000235:genetics*; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D004271:DNA, Fungal / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D005800:Genes, Fungal; D008969:Molecular Sequence Data; D005810:Multigene Family; D050901:Nitrate Reductase; D009565:Nitrate Reductases / Q000235:genetics*; D009572:Nitrite Reductases / Q000235:genetics*; D015183:Restriction Mapping; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
C079728:AreA protein, Aspergillus nidulans; D017931:DNA Primers; D004271:DNA, Fungal; D005656:Fungal Proteins; D014157:Transcription Factors; D009565:Nitrate Reductases; D009572:Nitrite Reductases; D050901:Nitrate Reductase