Mutational analysis of the open reading frames in the transposable element IS1.
IS1 is one of the smallest transposable elements found in bacteria (768 bp). It contains eight overlapping open-reading-frames (ORFs) greater than 50 codons, designated insA to insG and insB'. To determine which of the ORFs actually code for proteins involved in transposition, we have introduced amber codons into each ORF by site-directed mutagenesis which make neutral changes in the overlapping ORFs. Each mutant IS1 was then tested for its ability to mediate cointegrate formation in Su+ and Su- backgrounds. The mutant elements were also tested for trans-complementation in an IS1-free Salmonella background. Our results show that the products of the insA and insB genes are the only ones essential for cointegrate formation. We suggest that other ORFs may, however, encode accessory proteins.
Jakowec
M
M
Department of Molecular Biology, University of Southern California, Los Angeles 90089-1340.
Prentki
P
P
Chandler
M
M
Galas
D J
DJ
D000595:Amino Acid Sequence; D001483:Base Sequence; D004251:DNA Transposable Elements; D004926:Escherichia coli / Q000235:genetics*; D005822:Genetic Vectors; D008969:Molecular Sequence Data; D009154:Mutation; D010957:Plasmids; D012486:Salmonella typhimurium / Q000235:genetics*; D013045:Species Specificity
D004251:DNA Transposable Elements