Sequence analysis of the novel ORFG gene and protein in cyanobacteria

Unicellular cyanobacteria are vital primary producers in the ocean, are used as immune-boosting health supplements, and are a potential source of oil and hydrogen for sustainable fuel production. Innovations in DNA sequencing have produced a wealth of data, including many sequences encoding novel putative proteins. Here we present a study of one uncharacterized gene, orfG, found in Prochlorococcus, Synechococcus, Arthrospira, Acaryochloris, and a cyanophage. Nucleotide alignments of 34 orfG nucleotide sequences, 58 ef-tu sequences and 57 16S rRNA sequences were created. Phylogenetic trees were created from alignments using Maximum Likelihood algorithms. Bootstrapping was done using Garli (n=200). Selection acting on the orfG genes was assessed using FEL and a normalized dN-dS plot. Putative structures of the OrfG protein were created using homology modeling on ITASSER, and the homology of the OrfG protein to characterized proteins was determined using Hidden Markov Modeling. There is evidence of horizontal tr nsfer of orfG to Arthrospira species and to a thermophilic Synechococcus species. The OrfG protein appears to be an enzyme. Most of the OrfG protein sequences were assigned to the RmlC-like cupin protein superfamily, most closely resembling acireductdone dioxygenases. Similar proteins in cyanobacteria are active in the methionine salvage pathway. Knowledge of the function and interaction of genes can enhance understanding of the interaction of cyanobacteria with the environment and can aid in the cultivation of hardier, more productive strains for use as food or fuel.