Molecular rearrangement of lactose plasmid DNA associated with high-frequency transfer and cell aggregation in Lactococcus lactis 712.
High-frequency conjugation of the lactose plasmid pLP712 is associated with a constitutive cell aggregation phenotype and is facilitated by cointegration with a sex factor. Analysis of 23 independently derived enlarged lactose plasmids revealed that the sex factor DNA present in cointegrates varied in size. This suggested that more than simple cointegration with a sex factor plasmid was involved. Further analysis led to the discovery of a chromosomally located sex factor that could excise and be lost or exist as labile plasmid DNA. Cointegration with this sex factor was shown to be promoted by transposition of a copy of ISSI present on the lactose plasmid, and models are presented to account for the complex and variable structures of the resulting enlarged lactose plasmids.
Gasson
M J
MJ
AFRC Institute of Food Research, Norwich, UK.
Swindell
S
S
Maeda
S
S
Dodd
H M
HM
D001483:Base Sequence; D003227:Conjugation, Genetic / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics*; D005144:F Factor / Q000235:genetics*; D015321:Gene Rearrangement / Q000235:genetics; D013294:Lactococcus lactis / Q000235:genetics*; D007786:Lactose Factors / Q000235:genetics*; D008969:Molecular Sequence Data
D004269:DNA, Bacterial