Homing endonuclease

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Homing endonuclease ( homodimer ) on a DNA double strand

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

properties

Mobile genetic elements with homing endonucleases appear in different realms, e.g. B. in bacteriophages , bacteria , archaea , protists and eukaryotic cell organelles . The homing endonucleases perform functions such as DNA degradation , restriction enzymes , DNA repair enzymes , intron splicing factors and transcription factors. Homing endonucleases can be selectively inserted into an allele by sequence-specifically induced DNA double-strand breaks and a subsequent DNA repair in which there is currently no mobile genetic element with homing endonuclease. This is where the name homing comes from (English for 'target search', ' homing behavior ').

In contrast to type II restriction enzymes , homing endonucleases recognize longer sequences of 20 to 30 base pairs . As a result, a nucleic acid is still cut even in the case of individual point mutations that occur in the recognition sequence . According to their structure, they are divided into six groups in which four different catalytic protein structure motifs occur. These six groups are named after characteristic amino acid sequences LAGLIDADG, HNH, His-Cys box, GIY-YIG, PD- (D / E) xK or EDxHD.

Homing endonucleases are specifically modified in the course of a protein design in order to adapt their recognition sequences.

Individual evidence

  1. ↑ Gregory K. Taylor, Barry L. Stoddard: Structural, functional and evolutionary relationships between homing endonucleases and proteins from their host organisms . In: Nucleic acids research . tape 40 , no. 12 , July 2012, p. 5189-5200 , doi : 10.1093 / nar / gks226 , PMID 22406833 , PMC 3384342 (free full text).
  2. ↑ Barry L. Stoddard: Homing endonucleases: from microbial genetic invaders to reagents for targeted DNA modification . In: Structure (London, England: 1993) . tape 19 , no. 1 , January 12, 2011, p. 7–15 , doi : 10.1016 / j.str.2010.12.003 , PMID 21220111 , PMC 3038549 (free full text).
  3. ↑ Mohamed Hafez, Georg Hausner: Homing endonucleases: DNA scissors on a mission . In: Genome / National Research Council Canada = Génome / Conseil national de recherches Canada . tape 55 , no. 8 , August 2012, p. 553-569 , doi : 10.1139 / g2012-049 , PMID 22891613 ( PDF ).