Genomic structure of the luciferase gene from the bioluminescent beetle, Nyctophila cf. caucasica

Abstract

The gene coding for beetle luciferase, the enzyme responsible for bioluminescence in over two thousand coleopteran species has, to date, only been characterized from one Palearctic species of Lampyridae. Here we report the characterization of the luciferase gene from a female beetle of an Iranian lampyrid species, Nyctophila cf. caucasica (Coleoptera:Lampyridae). The luciferase gene was composed of seven exons, coding for 547 amino acids, separated by six introns spanning 1976 bp of genomic DNA. The deduced amino acid sequences of the luciferase gene of N. caucasica showed 98.9% homology to that of the Palearctic species Lampyris noctiluca. Analysis of the 810 bp upstream region of the luciferase gene revealed three TATA boxes and several other consensus transcriptional factor recognition sequences presenting evidence for a putative core promoter region conserved in Lampyrinae from -190 through to -155 upstream of the luciferase start codon. Along with the core promoter region the luciferase gene was compared with orthologous sequences from other lampyrid species and found to have greatest identity to Lampyris turkistanicus and Lampyris noctiluca. The significant sequence identity to the former is discussed in relation to taxonomic issues of Iranian lampyrids.

Figure 1.

The nucleotide sequence and genomic organization of the luciferase gene from Nyctophila caucasica (upper sequence) aligned with the cDNA luciferase sequence obtained from Lampyris noctiluca, GenBank accession number X89479 (lower sequence). Sequence identity is illustrated with a dot and deletions are indicated with a dash. Exon sequences are shown in bold uppercase, introns in lowercase. Amino acid differences between N. caucasica and L. noctiluca are shown underlined.

Figure 2.

Luciferase gene characterization from Nyctophila caucasica. A. Genome organization of the luciferase gene from N. caucasica and PCR primer positions. B. Deduced luciferase amino acid sequence alignment of N. caucasica (Nyct.) and Lampyris noctiluca (Lamp.) (Sala-Newby et al 1996).

Figure 3.

The 5′-flanking nucleotide sequence of the luciferase gene from Nyctophila caucasica. Nucleotides are numbered from the translation initiator ATG (bold) with A being position +1. The four putative TATA boxes at positions -63, -144, -166 and -190 and the CCAAT boxes at position -159 and -236 are indicated (underlined). The consensus binding sequences of transcription factor GATA elements are presented double underlined. Also shown is the 5′ end of the Lampyris noctiluca cDNA end product indicated by italicised bases (GenBank accession number X89479).

Figure 4.

The 5′-flanking nucleotide sequence of the luciferase gene from Nyctophila caucasica aligned with orthologous sequence from Photinus pyralis (GeneBank accession # M15077). Nucleotides are numbered from the translation initiator ATG (bold) with A being position +1. Two putative TATA boxes and a CCAAT box conserved in both sequences are highlighted in grey.

Figure 5.

A phylogenetic tree based upon amino acid sequences of the Nyctophila caucasica luciferase and fifteen known beetle luciferases. The maximum parsimony tree was obtained by a heuristic search with 1000 bootstrap replicates. Branch numbers refer to bootstrap values.