Site-specific Recombination - Classification: Tyrosine- vs. Serine- Recombinases

Classification: Tyrosine- vs. Serine- Recombinases

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Based on amino acid sequence homology and mechanistic relatedness most site-specific recombinases are grouped into one of two families: the tyrosine recombinase family or the serine recombinase family. The names stem from the conserved nucleophilic amino acid residue that they use to attack the DNA and which becomes covalently linked to it during strand exchange. Early members of the serine recombinase family were known as resolvase/invertases, while the founding member of the tyrosine recombinases, lambda- integrase, using attP/B recognition sites) differs from the now well known enzymes such as Cre (from the P1 phage) and FLP (from yeast S. cerevisiae) while famous serine recombinases include enzymes such as: gamma-delta resolvase (from the Tn1000 transposon), Tn3 resolvase (from the Tn3 transposon) and φC31 integrase (from the φC31 phage).

Although the individual members of the two recombinase families can perform reactions with same practical outcomes, the two families are unrelated to each other, having different protein structures and reaction mechanisms. Unlike tyrosine recombinases, serine recombinases are highly modular as was first hinted by biochemical studies, and later shown by crystallographic structures. Knowledge of these protein structures could prove useful when attempting to reengineer recombinase proteins as tools for genetic manipulation.