Dataset Information

AbiG, a genotypically novel abortive infection mechanism encoded by plasmid pCI750 of Lactococcus lactis subsp. cremoris UC653.

ABSTRACT: AbiG is an abortive infection (Abi) mechanism encoded by the conjugative plasmid pCI750 originally isolated from Lactococcus lactis subsp. cremoris UC653. Insensitivity conferred by this Abi manifested itself as complete resistance to phi 712 (936 phage species) with only partial resistance to phi c2 (c2 species). The mechanism did not inhibit phage DNA replication. The smallest subclone of pCI750 which expressed the Abi phenotype contained a 3.5-kb insert which encoded two potential open reading frames. abiGi (750 bp) and abiGii (1,194 bp) were separated by 2 bp and appeared to share a single promoter upstream of abiGi. These open reading frames showed no significant homology to sequences of either the DNA or protein databases; however, they did exhibit the typical low G+C content (29 and 27%, respectively) characteristic of lactococcal abi genes. In fact, the G+C content of a 7.0-kb fragment incorporating the abiG locus was 30%, which may suggest horizontal gene transfer from a species of low G+C content. In this context, it is notable that remnants of IS elements were observed throughout this 7.0-kb region.

SUBMITTER: O'Connor L

PROVIDER: S-EPMC168098 | biostudies-other | 1996 Sep

REPOSITORIES: biostudies-other

ACCESS DATA

Publications

AbiG, a genotypically novel abortive infection mechanism encoded by plasmid pCI750 of Lactococcus lactis subsp. cremoris UC653.

O'Connor L L Coffey A A Daly C C Fitzgerald G F GF

Applied and environmental microbiology 19960901 9

AbiG is an abortive infection (Abi) mechanism encoded by the conjugative plasmid pCI750 originally isolated from Lactococcus lactis subsp. cremoris UC653. Insensitivity conferred by this Abi manifested itself as complete resistance to phi 712 (936 phage species) with only partial resistance to phi c2 (c2 species). The mechanism did not inhibit phage DNA replication. The smallest subclone of pCI750 which expressed the Abi phenotype contained a 3.5-kb insert which encoded two potential open readin ...[more]

PMID: 8795193

Similar Datasets

Project description:Lactococcus lactis is one of the most commonly used lactic acid bacteria in the dairy industry. Activation of competence for natural DNA transformation in this species would greatly improve the selection of novel strains with desired genetic traits. Here, we investigated the activation of natural transformation in L. lactis subsp. cremoris KW2, a strain of plant origin whose genome encodes the master competence regulator ComX and the complete set of proteins usually required for natural transformation. In the absence of knowledge about competence regulation in this species, we constitutively overproduced ComX in a reporter strain of late competence phase activation and showed, by transcriptomic analyses, a ComX-dependent induction of all key competence genes. We further demonstrated that natural DNA transformation is functional in this strain and requires the competence DNA uptake machinery. Since constitutive ComX overproduction is unstable, we alternatively expressed comX under the control of an endogenous xylose-inducible promoter. This regulated system was used to successfully inactivate the adaptor protein MecA and subunits of the Clp proteolytic complex, which were previously shown to be involved in ComX degradation in streptococci. In the presence of a small amount of ComX, the deletion of mecA, clpC, or clpP genes markedly increased the activation of the late competence phase and transformability. Altogether, our results report the functionality of natural DNA transformation in L. lactis and pave the way for the identification of signaling mechanisms that trigger the competence state in this species.IMPORTANCELactococcus lactis is a lactic acid bacterium of major importance, which is used as a starter species for milk fermentation, a host for heterologous protein production, and a delivery platform for therapeutic molecules. Here, we report the functionality of natural transformation in L. lactis subsp. cremoris KW2 by the overproduction of the master competence regulator ComX. The developed procedure enables a flexible approach to modify the chromosome with single point mutation, sequence insertion, or sequence replacement. These results represent an important step for the genetic engineering of L. lactis that will facilitate the design of strains optimized for industrial applications. This will also help to discover natural regulatory mechanisms controlling competence in the genus Lactococcus.

Dataset Information

AbiG, a genotypically novel abortive infection mechanism encoded by plasmid pCI750 of Lactococcus lactis subsp. cremoris UC653.

Publications

AbiG, a genotypically novel abortive infection mechanism encoded by plasmid pCI750 of Lactococcus lactis subsp. cremoris UC653.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets