In:
Yeast, Wiley, Vol. 26, No. 2 ( 2009-02), p. 83-93
Abstract:
In Arxula adeninivorans nitrate assimilation is mediated by the combined actions of a nitrate transporter, a nitrate reductase and a nitrite reductase. Single‐copy genes for these activities ( AYNT1, AYNR1, AYNI1 , respectively) form a 9103 bp gene cluster localized on chromosome 2. The 3210 bp AYNI1 ORF codes for a protein of 1070 amino acids, which exhibits a high degree of identity to nitrite reductases from the yeasts Pichia anomala (58%), Hansenula polymorpha (58%) and Dekkera bruxellensis (54%). The second ORF ( AYNR1 , 2535 bp) encodes a nitrate reductase of 845 residues that shows significant (51%) identity to nitrate reductases of P. anomala and H. polymorpha . The third ORF in the cluster ( AYNT1 , 1518 bp) specifies a nitrate transporter with 506 amino acids, which is 46% identical to that of H. polymorpha . The three genes are independently expressed upon induction with NaNO 3 . We quantitatively analysed the promoter activities by qRT–PCR and after fusing individual promoter fragments to the phytase ( phyK ) gene from Klebsiella sp. ASR1. The AYNI1 promoter was found to exhibit the highest activity, followed by the AYNT1 and AYNR1 elements. Direct measurements of nitrate and nitrite reductase activities performed after induction with NaNO 3 are compatible with these results. Both enzymes show optimal activity at around 42°C and near‐neutral pH, and require FAD as a co‐factor and NADPH as electron donor. Copyright © 2009 John Wiley & Sons, Ltd.
Type of Medium:
Online Resource
ISSN:
0749-503X
,
1097-0061
Language:
English
Publisher:
Wiley
Publication Date:
2009
detail.hit.zdb_id:
1479172-9
SSG:
12
