<p>Phage integrases are enzymes that mediate unidirectional site-specific recombination between two DNA recognition sequences, the phage attachment site, attP, and the bacterial attachment site, attB [<cite idref="PUB00014061"/>]. Integrases may be grouped into two major families, the tyrosine recombinases and the serine recombinases, based on their mode of catalysis. Tyrosine family integrases, such as <taxon tax_id="10710">Bacteriophage lambda</taxon> integrase, utilise a catalytic tyrosine to mediate strand cleavage, tend to recognise longer attP sequences, and require other proteins encoded by the phage or the host bacteria.</p><p>The recombinases Cre from phage P1, XerD from <taxon tax_id="562">Escherichia coli</taxon> and Flp from yeast are members of the tyrosine recombinase family, and have a two-domain motif resembling that of lambda integrase, as well as sharing a conserved binding mechanism [<cite idref="PUB00014062"/>]. The structural fold of their catalytic core domains resemble that of Lambda integrase</p><p>This entry contains XerD-like putative tyrosine recombinases from the Streptococcaceae family.</p>