Diversity in the serine recombinases

SummaryMost site‐specific recombinases fall into one of two families, based on evolutionary and mechanistic relatedness. These are the tyrosine recombinases orλintegrase family and the serine recombinases or resolvase/invertase family. The tyrosine recombinases are structurally diverse and functionally versatile and include integrases, resolvases, invertases and transposases. Recent studies have revealed that the serine recombinase family is equally versatile and members have a variety of structural forms. The archetypal resolvase/invertases are highly regulated, only affect resolution or inversion and they have an N‐terminal catalytic domain and a C‐terminal DNA binding domain. Phage‐encoded serine recombinases (e.g.φC31 integrase) cause integration and excision with strictly controlled directionality, and have an N‐terminal catalytic domain but much longer C‐terminal domains compared with the resolvase/invertases. This high molecular weight group also contains transposases (e.g. TnpX from Tn4451). Other transposases, which belong to a third structurally different group, are similar in size to the resolvase/invertases but have the DNA binding domain N‐terminal to the catalytic dom