| site-specific integration of the streptomyces plasmid psam2 in mycobacterium smegmatis. | a method which allowed the stable integration of dna fragments at a single site (attb) in the chromosome of mycobacterium smegmatis was developed using an integrative element from streptomyces ambofaciens, psam2. vectors containing an escherichia coli replicon (pbr322), the kanamycin resistance gene from tn903 for selection in mycobacteria, and a fragment of psam2 containing the int gene as well as the attachment site (attp) were constructed and introduced to m. smegmatis by electroporation. tra ... | 1991 | 1665195 |
| plasmid cloning vectors that integrate site-specifically in streptomyces spp. | cloning vectors based on the streptomyces ambofaciens plasmid psam2 and the streptomycete phage phi c31 were developed for use in streptomyces spp. these vectors replicate in escherichia coli but integrate by site-specific recombination in streptomyces spp. both psam2-based and phi c31-based vectors transformed a number of different streptomyces spp; however, the phi c31-based vectors consistently transformed at higher frequencies than psam2-based vectors. southern analysis indicated that the ph ... | 1991 | 1995427 |
| construction of a series of psam2-based integrative vectors for use in actinomycetes. | we have developed vectors which allowed integration of cloned dna at a single site in the chromosome of streptomyces lividans 66. these vectors made use of (1) an escherichia coli replicon, (2) a thiostrepton (th)- and a streptomycin/spectinomycin-resistance gene for selection in streptomyces, (3) a 3.5-kb fragment of the streptomyces integrative plasmid psam2 containing its xis and int genes as well as its attachment site, attp, to direct the integration of the vectors at the chromosomal psam2 ... | 1990 | 2227452 |
| site-specific integration in streptomyces ambofaciens: localization of integration functions in s. ambofaciens plasmid psam2. | in streptomyces ambofaciens atcc 15154, an 11.1-kilobase element, psam2, exists as a single integrated copy in the chromosome. in s. ambofaciens 3212 (a derivative of atcc 15154), psam2 exists as a free, circular plasmid as well as an integrated element. bcli fragments from the free form of psam2 were cloned into an escherichia coli plasmid vector. by using gene transplacement methods, the chromosomally integrated form of psam2 was marked with a gene coding for apramycin resistance. this enabled ... | 1989 | 2536654 |
| the integrated conjugative plasmid psam2 of streptomyces ambofaciens is related to temperate bacteriophages. | streptomyces ambofaciens atcc23877 and derivatives contain the 11-kb element psam2 present in an integrated state or as a free and integrated plasmid. this element, able to integrate site-specifically in the genome of different streptomyces species, is conjugative and mobilizes chromosomal markers. besides these plasmid functions, we have shown that the site-specific recombination system of psam2 presents strong similarities with that of several temperate phages. the integration event is promote ... | 1989 | 2721504 |
| excision and integration of a self-transmissible replicon of streptomyces ambofaciens. | when streptomyces ambofaciens osf was crossed with the plasmid-free streptomyces lividans tk24, almost all s. lividans exconjugants contained the free 11.1-kb plasmid pos1. southern hybridizations showed that pos1 was derived from the integrated copy of previously recognized plasmid psam2 present in strain osf. a shorter derivative of pos1 was constructed carrying the tsr gene in a non-essential region, and this pos7 plasmid was used in transformation experiments with protoplasts of s. ambofacie ... | 1987 | 3436526 |
| plasmids in different strains of streptomyces ambofaciens: free and integrated form of plasmid psam2. | five strains of streptomyces ambofaciens were examined for their plasmid content. among these strains, four belong to the same lineage (strains b) and the other was isolated independently (strain a). a large plasmid (ca. 80 kb), called psam1 in this paper and already described, was present in all b strains, and absent in strain a. a second plasmid, not described before, was found as covalently closed circular dna in two of the four b strains. this plasmid with a size of 11.1 kb was called psam2. ... | 1984 | 6596483 |
| targets for psam2 integrase-mediated site-specific integration in the mycobacterium smegmatis chromosome. | an improved integrative cassette from plasmid psam2 has been constructed containing plasmid int and attp genes but excluding the xis gene, which should results in increased stability by suppression of the excision reaction. this cassette was included in both suicide and thermosensitive plasmids and used for integration in mycobacterium smegmatis. suicide plasmids containing this cassette integrated at a single site (attb1) in the m. smegmatis chromosome. the sequence of the attb1 site has been d ... | 1997 | 9353939 |