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J. Bacteriol., Mar 1997, 1867-1871, Vol 179, No. 6
A Gyohda, N Funayama and T Komano
The shufflon, a multiple DNA inversion system in the plasmid R64, consists
of four DNA segments flanked and separated by seven 19-bp repeat sequences.
Site-specific recombinations mediated by the rci product occur between each
inverted repeat sequence, resulting in inversions of the four segments
independently or in groups. The seven 19-bp repeat sequences are classified
into four types (repeat-a, -b, - c, and -d), according to their 3-bp
variable sequences. We individually cloned A, B, and C segments of the R64
shufflon and determined the in vivo inversion frequency of each segment.
The inversion frequencies of three segments differed greatly. The inversion
frequency declined in the following order: segments A, B, and C. Synthetic
19-mer oligonucleotides corresponding to both strands of repeat-a, -b, -c,
and -d sequences were inserted into appropriate sites of pBR322. The rci-
mediated DNA inversion occurred between two synthetic inverted repeats,
indicating that the 19-bp inverted repeat sequences are the sole elements
required in cis for the shufflon system. The inversion frequencies of DNA
segments flanked by various sequences indicate that the four types of
repeat sequences determine the inversion frequency of the four DNA segments
of the R64 shufflon. Deletion of a DNA segment flanked by direct repeat
sequences could not be detected.
Copyright © 1997, American Society for Microbiology
Analysis of DNA inversions in the shufflon of plasmid R64
Department of Biology, Tokyo Metropolitan University, Japan.
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