What is the purpose of homing endonucleases?

Homing endonucleases are highly specific and have evolved to cleave target sequences within cognate alleles without being overly toxic to the organism. They tolerate some individual base variation at their homing site, which ensures their propagation despite evolutionary drift of their target sequence.

What is intein homing?

. Homing endonucleases are rare-cutting enzymes encoded by inteins and introns. By making a site-specific double-strand break in the intronless or inteinless alleles, these nucleases create recombinogenic ends which engage in a gene conversion process that duplicates the intron or intein.

What enzyme cleaves introns?

Splicing occurs in several steps and is catalyzed by small nuclear ribonucleoproteins (snRNPs, commonly pronounced “snurps”). First, the pre-mRNA is cleaved at the 5′ end of the intron following the attachment of a snRNP called U1 to its complementary sequence within the intron.

What is a HNH?

HNH endonucleases are present in many bacteriophages and prophages. Most HNH endonucleases adopt a similar structure, comprising two antiparallel β-strands, an α-helix and a divalent metal ion bound in the active center. Thus, the HNH motif in HNH endonucleases is referred to as a ββα-metal fold.

How is the homing endonuclease used in the cell?

Homing endonuclease. They catalyze the hydrolysis of genomic DNA within the cells that synthesize them, but do so at very few, or even singular, locations. Repair of the hydrolyzed DNA by the host cell frequently results in the gene encoding the homing endonuclease having been copied into the cleavage site, hence the term ‘homing’ to describe…

What does homing endonuclease PI-Sce stand for?

The yeast homing endonuclease PI-Sce is a LAGLIDADG-type endonuclease encoded as an intein that splices itself out of another protein ( P17255 ).

Is the homing endonuclease part of the VSR superfamily?

The term ‘Vsr-like’ refers to the presence of a C-terminal nuclease domain that displays recognizable homology to bacterial Very short patch repair (Vsr) endonucleases. The structure has been solved in 2011, confirming the Vsr homology. Is considered part of the PD- (D/E)xk superfamily.

Why are homing endonucleases considered selfish genetic elements?

Although the origin and function of homing endonucleases is still being researched, the most established hypothesis considers them as selfish genetic elements, similar to transposons, because they facilitate the perpetuation of the genetic elements that encode them independent of providing a functional attribute to the host organism.

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