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 din oflagellate gene that has been cloned and sequenced at both cDNA and g enomic levels. Starting with a fragment from the 3'-end of the LBP cDN A that was found by immuno-screening of a cDNA library, genomic clones were obtained by the inverse polymerase chain reaction technique. Ful l-length cDNA clones were selected by screening a cDNA library by plaq ue hybridizations and by polymerase chain reaction amplifications. The LBP sequence has a 2004-nucleotide open reading frame coding for a pr otein of 668 amino acids (approximately 75 kDa). The reading frame and identity of the clone were confirmed by the sequence of an octapeptid e 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'-un translated region) and 158 nucleotides (3'-untranslated region) long, respectively. The LBP gene contains no introns and exhibits certain fe atures not typical for a eukaryotic gene. Its promoter does not includ e 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 a pparatus are maintained.