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. Author manuscript; available in PMC: 2013 Mar 1.
Published in final edited form as: Biochim Biophys Acta. 2011 Nov 29;1818(3):776–797. doi: 10.1016/j.bbamem.2011.11.015

Figure 2.

Figure 2

Nitrate reductase genes in Mtu. The Mtu genome includes two operons that respectively encode a nitrate reductase and a partial nitrate reductase. The latter probably includes nitrate-reductase pseudogenes resulting from two genomic deletions, the first being large, the second being small. Both operons are absent in Mle. (A) The narGHJI operon encodes the three nitrate reductase subunits, NarG (alpha), NarH (beta), and NarI (gamma). NarJ, the delta subunit, is a chaperone protein required for the assembly of this nitrate reductase complex. (B) The narK2X operon encodes two proteins: NarK2, a nitrite exporter, and NarX, a truncated nitrate reductase. The N-terminus of NarX is homologous to the first 256 aas of NarG. The next 160 aas of NarX are homologous to aas 5-164 of NarJ. The C-terminus of NarX is homologous to all 241 aas of NarI. narK2 and narI (γ) may be functional.