Controls the expression of several small proteins that may play a role in biofilm maturation. Binds to and represses the operator of the ycgZ-ymgA-ariR-ymgC operon and also regulates ynaK. Binding is antagonized by BluF upon blue light (470 nm) irradiation. Blue light may increase the affinity of BluF for BluR, allowing it to be released from its operator. Interacts with BluF. Expression is strongly activated (7-fold at 16 degrees Celsius compared to 37 degrees) at low temperature. 3- to 20-fold derepression of several genes coding for small proteins including the ycgZ-ymgA-ariR-ymgC operon. While the BluR/F system is induced at low temperatures under blue light irradiation, it is not essential for growth under these conditions. When both lon and bluR are disrupted, levels of OmpF decrease, leading to lower drug susceptibility, with a greater effect at 26 degrees than at 37 degrees Celsius. The mechanism is not yet understood.