Localization of genes responsible for replication and immunity to colicin A on plasmid ColA-CA31

Abstract

The region containing the origin and regulatory sites for replication as well as the immunity gene (iaa) have been localized on the plasmid ColA-CA31. The region involved in replication functions of ColA can be hybridized with that of ColE1. It is located between 1 and 1 kb on the plasmid map previously published (Morlon et al. 1982a). A 0.50 Kb HincII fragment of ColA can be weakly hybridized to the ColE1 immunity region. This fragment contains iaa since directed in vitro mutagenesis at an internal restriction site can abolish the immunity to colicin A; however, it does not contain the entire iaa. Knowing the localization of regions involved in autonomous DNA replication and immunity, a mini-ColA plasmid was constructed that contains these two regions. The mini-ColA of 2.8 Kb can be amplified in the presence of chloramphenicol and confers the immunity to transformants. It thus constitutes a useful cloning vector. Expression of ColA and of the various constructed plasmids in the maxicell system suggests that the immunity protein has a molecular weight of about 18-20 Kd.

Isolation and identification of a bacteriocin with antibacterial and antibiofilm activity from Citrobacter freundii

“…The gene that codes for the antimicrobial, colA - 43864 , is on a small plasmid almost identical in sequence to the well-characterized colicin A-producing plasmid from C. freundii strain CA31 (Morlon et al 1988a). The colA - CA31 gene from C. freundii strain CA31 was previously described as a type-A bacteriocin (Davies and Reeves 1975) and used for several studies to characterize the role of “A” type bacteriocins (Varenne et al 1981; Crozel et al 1983). Based on the ~99% sequence identity, we predict that the biofilm-controlling ColA-43864 described in this study is also an “A” type bacteriocin.…”

The promoters of the genes for colicin production, release and immunity in the ColA plasmid: effects of convergent transcription and Lex A protein

“…The bacterial host strain W3110 and C600, plasmids pBR322 and pColA have been previously described (6). The strain W3110 (pColA9, pColA or pDV5) was grown in the M19 minimal medium supplemented with glucose (4 g/l), casamino acids (4 g/l), thiamin (5 mg/l), and ampicillin (50 mg/1).…”