Chloramphenicol resistance in Streptomyces coelicolor A3(2): Possible involvement of a transposable element

Abstract

The transfer of a Chl element, causing resistance to chloramphenicol in Streptomyces coelicolor A3(2), was studied in NF x SCP1- superfertile crosses. When the Chl element is on the donor side (NF) its transfer to the recombinant cells was virtually total as if the element acted as a second concomitant transfer origin. When the Chl element was on the recipient side (SCP1-) it was never displaced by the immigrant chromosome even when the region facing chl+ was selected for. A fraction of the original Chl- mutants presented a requirement for arginine (ArgB-). A Chl- mutant gave rise spontaneously to ArgB- derivatives at high frequency. The same ArgB- requirement come out at high frequency among Chl- derivatives from a cross NFChl- x SCP1-Chl+ in which neither parent required arginine or produced spontaneously arginine-less derivatives. It is suggested that the Chl element is a "transposable element" (Tn) presumably associated with "insertion sequences" (IS). The insertional inactivation of the Chl element may be accompanied or followed by a deletion in the adjacent ArgB gene.

Relationship of an unstable argG gene to a 5.7-kilobase amplifiable DNA sequence in Streptomyces lividans 66

“…Previous attempts to genetically map the Camr determinant and argG genes in S. coelicolor A3(2) revealed ambiguities (10,35,36). We believed that the presence in the genome of one parental type of large DNA deletions and amplified DNA sequences could drastically affect segregation patterns, giving rise to ill-defined map positions.…”

“…(19,26,27,30,36), although they are not correlated with amplification of DNA sequences. For S. cattleya, the gene for argininosuccinate synthase, argG, has been cloned and used to demonstrate that the Arg phenotype in variant strains results from deletion of this gene (26,39).…”

“…lividans exhibits a stepwise pathway of instability of Camr and argG (1,7). Both these spontaneous highfrequency mutations were previously identified in S. coelicolor A3(2) (5, 10, 36), but it was not possible to locate these genes to fixed positions on a genetic map (10,35,36). Genetic transposition was offered as an explanation, but, subsequently it has been argued that some of the original data were incorrectly interpreted (4).…”

DNA Amplification and Genetic Instability inStreptomyces

“…References: (1) Rcdshuw et ell. (1979); (2) Matsubara-Nakano1 Kataoka and Oga\vara (1980); (3) Sermonti et of. (1978); (4) Nakano, Ozawa and Ogcl\v<ua (1980); (5) Altcnbuchncr and Cullum (1984); (6) lshiharn.…”

“…Sermonti et al, (1977) interpreted emIR x Cml s matings as showing evidence of high-frequency transfer of the emiR gene independently of chromosomal gene transfer and concluded that the eml R gene \vas carried on an extrachromosomal element; however~Freeman~Bibb and Hopwood (1977) showed that the emIR gene was not carried on any known extrachromosomal element in S. coelicolor. It was subsequently suggested that the CmP~gene was on a transposable element that transposed between different chromosomal locations at such a high frequency that any population of cells contained individuals with the emIR gene at different locations, thus confounding normal mapping procedures (Sermonti et al, 1978;SermontiL anfaloni and Micheli, 1980). These authors tried to overcome this problem by splitting transconjugants into different classes where each class should be derived from parents with the emIR in a different particular location.…”