New Perspectives Related to the Bioluminescent System in Dinoflagellates: Pyrocystis lunula, a Case Study

Pyrocystis lunula is considered a model organism due to its bioluminescence capacity linked to circadian rhythms. The mechanisms underlying the bioluminescent phenomenon have been well characterized in dinoflagellates; however, there are still some aspects that remain an enigma. Such is the case of the presence and diversity of the luciferin-binding protein (LBP), as well as the synthesis process of luciferin. Here we carry out a review of the literature in relation to the molecular players responsible for bioluminescence in dinoflagellates, with particular interest in P. lunula. We also carried out a phylogenetic analysis of the conservation of protein sequence, structure and evolutionary pattern of these key players. The basic structure of the luciferase (LCF) is quite conserved among the sequences reported to date for dinoflagellate species, but not in the case of the LBP, which has proven to be more variable in terms of sequence and structure. In the case of luciferin, its synthesis has been shown to be complex process with more than one metabolic pathway involved. The glutathione S-transferase (GST) and the P630 or blue compound, seem to be involved in this process. In the same way, various hypotheses regarding the role of bioluminescence in dinoflagellates are exposed.

An ”omic“ approach to Pyrocystis lunula: New insights related with this bioluminescent dinoflagellate

Background: Pyrocystis lunula (Schutt) is a photoautotrophic dinoflagellate without armored, frequently found in marine environments. Today, there are several biotechnological applications derived from the bioluminescent system of this species. From a post-genomic perspective, in order to study the whole proteome of P. lunula, an ”omic“ approach (transcriptomic-proteomic analysis) was assessed using fresh microalgae samples. Results: A total of 80,874,825 raw reads were generated (11,292,087,505 pb; 55.82 % GC) by mRNA sequencing. Very high quality sequences were assembled into 414,295 contigs (219,203,407 pb; 55.38 % GC) by the Trinity software, generating a comprehensive reference transcriptome for this species. Then, a P. lunula proteome was predicted and further employed through the first proteomic analysis on this species. A total of 17,461 peptides were identified, yielding 3,182 protein identification hits. The identified proteins were further categorized according to functional description and gene ontology classification. Conclusions: The first comprehensive molecular analysis of the microalgae P. lunula using both, transcriptomic and proteomic approaches, has been reported. Proteomic results represent a valuable piece in the understanding of this microalgae regulation at molecular level, and shed light on the identification of important factors involved in gene expression regulation. Indeed, the presence of the luciferin-binding protein (LBP), which had not been described so far in the genus Pyrocystis has been highlighted.