Homing endonuclease, LAGLIDADG/HNH (IPR001982)

Short name: Endonuc_LAG/HNH

Domain relationships


The LAGLIDADG and HNH domains of site-specific DNA endonucleases encoded by viruses, bacteriophages as well as archaeal, eukaryotic nuclear and organellar genomes are characterised by the sequence motifs 'LAGLIDADG' and 'HNH', respectively [PMID: 9187655, PMID: 9254693]. Phylogenetic analysis of the two domains indicates a lack of exchange of endonucleases between different mobile elements (environments) and between hosts from different phylogenetic kingdoms. However, there does appear to have been considerable exchange of endonuclease domains amongst elements of the same type. Such events are suggested to be important for the formation of elements of new specficity [PMID: 9358175].

'Homing' is the lateral transfer of an intervening genetic sequence, either an intron or an intein, to a cognate allele that lacks that element. The end result of homing is the duplication of the intervening sequence. The process is initiated by site-specific endonucleases that are encoded by open reading frames within the mobile elements. These endonucleases may be contrasted with a variety of enzymes involved in nucleic acid strand breakage and rearrangement, particularly restriction endonucleases. They are encoded within the intervening sequence and there are interesting limitations on the position and length of their open reading frames, and therefore on their structures. These enzymes display a unique strategy of flexible recognition of very long DNA target sites. This strategy allows these sequences to minimize nonspecific cleavage within the host genome, while maximizing the ability of the endonuclease to cleave closely related variants of the homing site [PMID: 10487208].

GO terms

Biological Process

GO:0006314 intron homing

Molecular Function

GO:0003677 DNA binding
GO:0004519 endonuclease activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.