Molecular cloning and genomic organization of a gene for luciferin-binding protein from the dinoflagellate Gonyaulax polyedra.

The circadian expressed luciferin-binding protein (LBP) gene from the marine bioluminescent alga Gonyaulax polyedra represents the first dinoflagellate gene that has been cloned and sequenced at both cDNA and genomic levels. Starting with a fragment from the 3'-end of the LBP cDNA that was found by immunoscreening of a cDNA library, genomic clones were obtained by the inverse polymerase chain reaction technique. Full-length cDNA clones were selected by screening a cDNA library by plaque hybridizations and by polymerase chain reaction amplifications. The LBP sequence has a 2004-nucleotide open reading frame coding for a protein of 668 amino acids (approximately 75 kDa). The reading frame and identity of the clone were confirmed by the sequence of an octapeptide obtained from a purified fragment of CNBr-treated LBP. A variant LBP cDNA was found to differ in sequence by approximately 11% at the DNA level. The untranslated regions of the mRNA are 111 nucleotides (5'-untranslated region) and 158 nucleotides (3'-untranslated region) long, respectively. The LBP gene contains no introns and exhibits certain features not typical for a eukaryotic gene. Its promoter does not include the typical TATA box within approximately 50 nucleotides upstream of the transcription start site, and the usual poly(A+) signal (AAUAAA) is not present on the end of the LBP mRNA. The copy number of the gene is very high (approximately 1000 copies/cell). However, the universal genetic code and conserved positions relevant for the translational apparatus are maintained.