The structural genes for NRZ, the second nitrate reductase of Escherichia coli, have been sequenced. They are organized in a transcription unit, narZYWV, encoding four subunits, NarZ, NarY, NarW and NarV. The transcription unit is homologous (73% identity) to the narGHJI operon which encodes the genes for NRA, the better characterized nitrate reductase of this organism. The level of homology between the corresponding polypeptides ranges from 69% for the NarW/NarJ pair to 86% for the NarV/ Narl pair. The NarZ polypeptide contains the five conserved regions present in all other known molybdoproteins of E. coli and their relative order is the same. The NarY polypeptide, which contains the same four cysteine clusters in the same order as NarH, is probably an electron transfer unit of the complex. Upstream of narZ, an open reading frame, ORFA, is present which could encode a product which has homology (73% identity) with the COON-terminal end of NarK. The ORFA-narZ intergenic region, however, is about 80 nucleotides long and does not contain the cis-acting elements, NarL and Fnr boxes, nor the terC4 terminator sequence present in the 500 nucleotide narK-narG intergenic region. This might explain why the nar-ZYWV and the narGHJI operons are regulated differently. Our results tend to support the hypothesis that a DNA fragment larger than that encompassing the narGHJI genes has been duplicated.
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Bilous PT, Cole ST, Anderson WF, Weiner JH (1988) Nucleotide sequence of the DmsABC operon encoding the anaerobic dimethylsulfoxide reductase of Escherichia coli. Mol Microbiol 2:785–795
Blasco F, Iobbi C, Giordano G, Chippaux M, Bonnefoy V (1989) Nitrate reductase of Escherichia coli: completion of the nucleotide sequence of the nar operon and reassessement of the role of the α and β subunits in iron binding and electron transfer. Mol Gen Genet 218:249–256
Bonnefoy V, Burini IF, Giordano G, Pascal MC, Chippaux M (1987) Presence in the “silent” terminus region of the Escherichia coli K12 chromosome of cryptic gene(s) encoding a new nitrate reductase. Mol Microbiol 1:143–150
Bonnefoy-Orth V, Lepelletier M, Pascal MC, Chippaux M (1981) Nitrate reductase and cytochrome b nitrate reductase structural genes as parts of the nitrate reductase operon. Mol Gen Genet 181:535–540
Das A, Yanofsky C (1984) A ribosome binding site sequence is necessary for efficient expression of the distal gene of a translationally-coupled gene pair. Nucleic Acids Res 12:4757–4568
Edwards ES, Rondeau SS, DeMoss JA (1983) chlC(nar) operon of Escherichia coli includes genes for α and β subunits of the nitrate reductase. J Bacteriol 153:1513–1520
Garnier J, Osguthorpe DJ, Robson B (1978) Analysis of the accuracy and implication of simple methods for predicting the secondary structure of globular proteins. J Mol Biol 120:97–120
Hidaka M, Akiyama M, Horiuchi T (1988) A consensus sequence of the three DNA replication terminus sites on the E. coli chromosome is highly homologous to the terR sites of the R6K plasmid. Cell 55:467–475
Iobbi C, Santini CL, Bonnefoy V, Giordano G (1987) Biochemical and immunological evidence for a second nitrate reductase in Escherichia coli K12. Eur J Biochem 168:451–459
Kyte J, Doolittle RF (1982) A simple model for displaying the hydropathic character of a protein. J Mol Biol 157:105–132
Li SF, Rabi T, DeMoss JA (1985) Delineation of two distinct regulatory domains in the 5′ region of the nar operon of Escherichia coli. J Bacteriol 164:75–32
Maniatis T, Fritsch EF, Sambrook J (1982) Molecular cloning: a laboratory manual. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, New York
McPherson MJ, Baron AJ, Pappin DJC, Wootton JC (1984) Respiratory nitrate reductase of Escherichia coli. Sequence identification of the large subunit gene. FEBS Lett 177:260–264
Noji S, Nohno T, Saito T, Taniguchi S (1989) The narK gene product participates in nitrate transport induced in Escherichia coli nitrate-respiring cells. FEBS Lett 252:139–143
Russel M, Kidd S, Kelley MR (1986) An improved filamentous helper phage for generating single-stranded plasmid DNA. Gene 45:333–338
Sanger F, Nicklen S, Coulson AR (1977) DNA sequencing with chain-terminating inhibitors. Proc Nail Acad Sci USA 74:5463–5467
Sodergren EJ, DeMoss JA (1988) narI region of the Escherichia coli nitrate reductase (nar) operon contains two genes. J Bacteriol 170:1721–1729
Stewart V (1988) Nitrate respiration in relation to facultative metabolism in Enterobacteriaceae. Microbiol Rev 52:190–232
Wain-Hobson S, Sonigo P, Danos O, Cole S, Alizon M (1985) Nucleotide sequence of the AIDS virus LAV. Cell 40:9–17
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Blasco, F., Iobbi, C., Ratouchniak, J. et al. Nitrate reductases of Escherichia coli: Sequence of the second nitrate reductase and comparison with that encoded by the narGHJI operon. Molec. Gen. Genet. 222, 104–111 (1990). https://doi.org/10.1007/BF00283030
- Nitrate reductase
- nar operons
- DNA sequence
- Gene duplication