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Published on: October 23, 2017
A jumping gene in streptomyces coelicolor A3(2)
Summary
Mapping the chloramphenicol resistance (cmlR) gene in Streptomyces coelicolor is challenging due to its variable chromosomal locations. Fresh isolates reveal consistent cmlR gene positioning, suggesting transposon activity.
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- The chloramphenicol resistance (cmlR) gene in Streptomyces coelicolor A3(2) exhibits mapping difficulties in stock strains.
- This complexity is likely due to the gene's variable integration sites within different chromosomal subclones.
Purpose of the Study:
- To investigate the precise chromosomal locations of the cmlR gene in Streptomyces coelicolor.
- To elucidate the role of transposons in the dissemination and stability of cmlR.
Main Methods:
- Analysis of fresh isolates from chloramphenicol-resistant (CmlR) strains.
- Characterization of CmlR strains derived from chloramphenicol-sensitive (CmlS) revertants.
- Genetic mapping techniques to determine gene loci.
Main Results:
- Fresh isolates and revertant strains display unequivocal and consistent locations for the cmlR gene.
- Established cmlR loci are situated between cysA and metA, and to the right of argA.
- Evidence suggests cmlR is part of a transposon (SCTn1) also containing argG, tra, and amy genes.
- Observation of cmlR gene disjoining from argG in a revertant indicates transposon splitting and transposition.
Conclusions:
- The variable mapping of cmlR is attributed to its location on mobile genetic elements, specifically transposons.
- The SCTn1 transposon demonstrates instability, capable of splitting and undergoing partial transposition.
- Transposons may be widespread in the Streptomyces genus, contributing to genetic diversity and adaptation.
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