Abstract

Guanine quadruplex (G4) structures are an intriguing new focus in the field of molecular genetics. G4 secondary structures are formed in DNA and have been shown to block transcription of downstream genes through in vivo experiments in both eukaryotes and prokaryotes. However, no such studies have explored the inclusion or functionality of G4 sequences in bacteriophage genomes. We analyzed 31 phages across 6 clusters and discovered 59 putative guanine quadruplex sequences while focusing on intra-cluster homology, using the search algorithm G3-5+N1-7+ G3-5+N1-7+ G3-5+N1-7+ G3-5. Our characterization of the putative sequences showed a high level of G4 sequence conservation within both the B1 and P1 clusters. We then designed a cloning strategy using existing 3A assembly methods to allow for future in vivo characterization of phage G4 sequences and their role in transcription. We are cloning phage-based G4 sequences between promoter and reporter gene sequences using iGEM plasmid constructs. Effects of the phage-based G4 insertions on transcription of the reporter gene will be measured to reveal potential roles of these sequences in gene regulation.