THE LUMAZINE PROTEIN-ENCODING GENE IN PHOTOBACTERIUM-LEIOGNATHI IS LINKED TO THE LUX OPERON

The nucleotide (nt) sequence of the lumP (EMBL accession No. X65612) g ene of Photobacterium leiognathi PL741 was determined and the amino ac id (aa) sequence deduced. The encoded aa sequence of lumP was identifi ed as that of the lumazine protein (LumP) by homology with that of Pho tobacterium phosphoreum (56%). This small protein has a calculated M(r ) of 19997 and comprises 186 aa residues. Biochemical studies suggeste d that LumP is the protein which, when combined with luciferase, is re sponsible for the bioluminescent spectrum shift from blue-green light (490-505 nm) to blue (470 nm) in P. leiognathi. The nt sequence of the flanking region showed that lumP is linked to the lux operon but runs in the opposite direction. The gene order of the lumP and lux operon is as follows: lumP-R&R-luxC-luxD-luxA-luxB-luxN-luxE-->; the R&R regu latory region sequence included two promoter systems, P(R) for the lux operon and P(L)for the lumP or the lum operon.