Homing endonuclease

A homing endonuclease called an endonuclease with an asymmetric recognition sequence. Homing endonucleases are mostly in mobile genetic elements, such as some self-splicing introns ( group I or II) or some inteins ago, where they serve to initiate the insertion of their mobile genetic element. Therefore, their genes belong to the selfish DNA.

Properties

Mobile genetic elements of homing endonucleases occur in different kingdoms, eg bacteriophages, bacteria, archaea, protists and eukaryotic cell organelles. The homing endonucleases fulfill this functions as DNA degradation, restriction enzymes, DNA repair enzymes, intron splicing and transcription factors. Homing endonucleases can be inserted through a sequence-specific induced DNA double-strand breaks and a DNA repair following onset selectively in one allele in which previously is not a mobile genetic element of homing endonuclease. Hence the name homing (English for, target search ',' homing behavior ') is derived.

In contrast to the type II restriction enzymes homing endonucleases recognize longer sequences 20 to 30 base pairs. Wherein a nucleic acid will also be cut in single point mutation occurring in the recognition sequence. They are divided into six groups according to their structure, which occur four different catalytic protein structural motifs. These six groups are named according to the amino acid sequences characteristic LAGLIDADG, HNH, His- Cys box, GIY - YIG, PD - (D / E) xK or EDxHD.

Homing endonucleases are specifically altered in the course of a protein design to suit their recognition sequences.