Insertion sequence

Insertion sequences ( IS insertion sequence or element) are short, movable pieces of DNA in bacteria, archaea and some bacteriophages with counter- repetitive end sequences ( engl. inverted repeats ), which can be inserted into DNA. Insertion sequences are a form of selfish DNA.

Properties

• Have a size of about 800-2000 bp
• Be about every 10 million cell divisions once transposed ( ie, offset built-in)
• They are installed at integration sites ( palindromes ) in structural genes, they inhibit their function by
• Usually consist of opposing repeats at the ends and open reading frames in the interior
• So encode their "own" transposase for integration into the genome ( thus one type of DNA transposons )

In the trans position, the integration site is staggered by a few base pairs of cut ( the transposase ), the repeats of the IC element can be inverted and attached to the interfaces of the gaps are closed by a general DNA synthesis.

The IS elements have a mutagenic effect, as they are mostly destroyed by their insertion in an open reading frame of gene function by shifting the reading frame ( raster relapsing mutation). It is also possible that homologous sequences on a plasmid and the IS elements in the chromosome of bacteria, the plasmid is inserted into the bacterial chromosome.

The inverted repeats ( IR) flanking either side of the coding for the transposase area. They consist of not necessarily identical 10 to 50 bp long DNA sequences.

Swell

Catherine Munk (ed.): pocket textbook Biology: Microbiology. Thieme, Stuttgart 2008, ISBN 978-3-13-144861-3, pp. 238-239

Michael T. Madigan, John M. Martinko, David A. Stahl, David P. Clark: Brock Biology of Microorganisms. 13th edition. Addison - Wesley Professional, ISBN 978-0321735515, pp. 286-287

• Repetitive DNA
• Mobile genetic element