Characterisation of a novel plasmid p9785S from Lactobacillus johnsonii FI9785.
Lactobacillus johnsonii FI9785, a strain originally isolated from poultry gastrointestinal tract for its probiotic function as a competitive excluder of pathogens, was found to contain two cryptic plasmids of 3.5 and 25.6 kb. Nucleotide sequence analysis of the entire small plasmid, designated p9785S (3471 bp), indicated a G+C content of 35.8%, and revealed two open reading frames (orfs). The product of orf1 exhibited similarity to the relaxases of mobilizable plasmids, whereas the product of orf2 displayed significant homology to replication proteins of plasmids which use the rolling circle mode of replication. A conserved double-strand origin of replication was also present in p9785S. A definite minus origin was not identified although a region with extensive intrastrand base pairing potential was revealed. A 1.4 kb fragment encoding the chloramphenicol resistance gene was cloned into p9785S and the resulting vector, pFI2431, was stably maintained when introduced into the parent Lactobacillus cells.
Horn
Nikki
N
Food Safety Science Division, Institute of Food Research, Norwich Research Park, Colney Lane, Norwich, Norfolk NR4 7UA, UK.
Wegmann
Udo
U
Narbad
Arjan
A
Gasson
Michael J
MJ
D000595:Amino Acid Sequence; D002702:Chloramphenicol Resistance / Q000235:genetics; D003001:Cloning, Molecular; D005819:Genetic Markers; D007778:Lactobacillus / Q000235:genetics* / Q000502:physiology; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010957:Plasmids / Q000235:genetics*; D019936:Probiotics; D018741:Replication Origin; D017421:Sequence Analysis; D017386:Sequence Homology, Amino Acid
D005819:Genetic Markers