Nitrate reductase chaperone, NarJ (IPR003765)

Short name: NO3_reductase_chaperone_NarJ

Overlapping homologous superfamilies

Family relationships


The nitrate-reducing system, nitrate reductase EC:, is stimulated by anaerobiosis, nitrate, and nitrite. The NarJ/delta subunit is not part of the nitrate reductase enzyme but is needed for assembly of the multisubunit enzyme complex. In the absence of the delta subunit the core alpha beta enzyme complex is unstable [PMID: 9738886]. The delta subunit is essential for enzyme activity in vivo and in vitro. Although NarJ is required for correct assembly of active enzyme, it dissociates and is not part of the active enzyme. The Escherichia coli (strain K12) NarJ, which is a chaperone required for proper molybdenum cofactor insertion and final assembly of the membrane-bound respiratory nitrate reductase 1. NarJ is required for the insertion of molybdenum into the apo-NarG subunit, maybe by keeping NarG in an appropriate competent-open conformation for the molybdenum cofactor insertion to occur. NarJ maintains the apoNarGH complex in a soluble state. Upon insertion of the molybdenum cofactor, NarJ seems to dissociate from the activated soluble NarGH complex, before its association with the NarI subunit on the membrane [PMID: 1732220, PMID: 9305880, PMID: 9632249].

GO terms

Biological Process

GO:0051131 chaperone-mediated protein complex assembly

Molecular Function

GO:0051082 unfolded protein binding

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.