Transcription factor NiaR negatively controls NAD biosynthesis and salvage of niacin (vitamin B3) as a NAD precursor. It was originally investigated in Bacillus subtilis as a niacin-responsive YrxA repressor. NiaR regulators constitute a unique protein family. The comparative genomic approach was used to identify candidate DNA binding motifs of NiaR and reconstruct the NiaR regulons in various bacteria from the Bacillus/Clostridium group (Firmicutes) and the Thermotagales . Representatives of two distinct types of candidate NiaR-binding motifs, characteristic of the Firmicutes (Bacillus subtilis) and Thermotogales (Thermotoga maritima), were verified by electophoretic mobility shift assay (EMSA).
It was also shown that nicotinic acid (niacin) acts as a co-repressor for the NiaR regulator [18276644