Abstract
Duplications of the Escherichia coli chromosomal region carrying the glyS and xylloci can be selected by deoxyadenosine treatment of trpA36 glyS L glyTsu AGA or ( glyUsu AGA) cultures. The deoxyadenosine lowers the suppression efficiency of these missense suppressors, and growth is severely limited by the resulting tryptophan starvation. Prolonged growth in the presence of 250 μg deoxyadenosine/ml leads to the accumulation of mutants with two (or more) copies of the allele for glycyl-transfer RNA synthetase, glyS L. The same duplication is obtained each time the selective pressure is applied. This was shown by physically isolating the duplicated region in the form of circular DNA excised from the duplication by recombination. In repeated experiments, a circular species 140,000 base-pairs in size was isolated. These results are interpreted as showing that there are two loci, one on each side of the glyS locus, and spaced 140,000 base-pairs apart, which are prone to recombining with each other in a manner leading to a genetic duplication.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
