BIOL308 Lecture Notes - Lecture 15: Insertion Sequence, Endonuclease, Prophage
16 Jul 2014
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Occurs between sequences with a limited stretch of similarity; involves specific sites. Inversion [eg. expression of alternate genes - inversion of dna sequence/gene by dna invertases) Insertion [eg. infection - insertion of bacteriophages in the bacterial genome by dna integrase] Deletions [ eg. deletion o fbacteriophages from the bacterial genome - different pathway for the bacterium] In all three cases the components of the site-directed recombination are: Rearrangement enzymes - recombinases [in some cases accessory proteins are required] Site-specific recombinases cleave and rejoin dna using a covalent protein-dna intermediate a) b) Note: recombinases do recombinations, cleave and ligate dna using covalent protein dna interactions, through protein-dna intermediate, similar to what topoisomerase does. ** exonuclease cuts from the end of the molecule (3 or 5" end) where endonuclease cuts inside the dna. Recombination site (specific sequence) - places of dna exchange. Have a percentage of homology, not 100% homologous. Two different dna molecules insertion [integration; lambda integrase]
