title: Sequence diversity and functional conservation of the origin of replication in lactococcal prolate phages.
abstract: Prolate or c2-like phages are a large homologous group of viruses that infect the bacterium Lactococcus lactis. In a collection of 122 prolate phages, three distinct, non-cross-hybridizing groups of origins of DNA replication were found. The nonconserved sequence was confined to the template for an untranslated transcript, P(E)1-T, 300 to 400 nucleotides in length, while the flanking sequences were conserved. All three origin types, despite the low sequence homology, have the same functional characteristics: they express abundant P(E)1-T transcripts and can function as origins of plasmid replication in the absence of phage proteins. Using chimeric constructs, we showed that hybrids of two nonhomologous origin sequences failed to function as replication origins, suggesting that preservation of a particular secondary structure of the P(E)1-T transcript is required for replication. This is the first systematic survey of the sequence and function of origins of replication in a group of lactococcal phages.
authors.affiliation: Institute of Molecular BioSciences, Massey University, Palmerston North, New Zealand. J.Rakonjac@massey.ac.nz
authors.forename: Jasna
authors.initials: J
authors.lastname: Rakonjac
authors.forename: Lawrence J H
authors.initials: LJ
authors.lastname: Ward
authors.forename: Anja H
authors.initials: AH
authors.lastname: Schiemann
authors.forename: Paul P
authors.initials: PP
authors.lastname: Gardner
authors.forename: Mark W
authors.initials: MW
authors.lastname: Lubbers
authors.forename: Paul W
authors.initials: PW
authors.lastname: O'Toole
mesh_terms: D001435:Bacteriophages / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D001483:Base Sequence; D017931:DNA Primers; D004926:Escherichia coli / Q000821:virology; D014644:Genetic Variation; D013294:Lactococcus lactis / Q000821:virology*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010802:Phylogeny; D010957:Plasmids; D018741:Replication Origin; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic
chemical_list: D017931:DNA Primers