(A) Multiple sequence alignment of the DNA-binding ALOG and catalytic tyrosine recombinase domains. Proteins are labeled by their gene names, species abbreviations and Genbank index numbers separated by underscores. Sequences are colored based on their conservation at 90% consensus. The coloring scheme, consensus abbreviations and secondary structure representation are shown in the key. Absolutely conserved residues are shaded red. For residues encompassing the tyrosine recombinase N-terminal/ALOG domain, the consensus was computed based on the conservation of the alignment positions in ALOG domain-containing proteins. Also highlighted are the DNA-contacting residues derived from crystal structures of tyrosine recombinase DBDs, and the catalytic residues of the tyrosine recombinase catalytic domain. Species abbreviations are as follows. Adig : Acropora digitifera; Alyr : Arabidopsis lyrata; Atha : Arabidopsis thaliana; BPP1 : Enterobacteria phage P1; BPlambda : Enterobacteria phage lambda; Bflo : Branchiostoma floridae; Brap : Brassica rapa; Ccin : Coprinopsis cinerea; Ddis : Dictyostelium discoideum; Ecol : Escherichia coli; Esil : Ectocarpus siliculosus; Lgig : Lottia gigantea; Nvec : Nematostella vectensis; Ogra : Oryza grandiglumis; Osat : Oryza sativa; Ppat : Physcomitrella patens; Sbic : Sorghum bicolor; Skow : Saccoglossus kowalevskii; Smoe : Selaginella moellendorffii; Spra : Spirogyra pratensis; Vcho : Vibrio cholerae; Zmay : Zea mays. (B) Cartoon representation of the N-terminal DBD of the CRE recombinase (PDB: 1CRX) in complex with DNA illustrating the position of the predicted ALOG domain zinc ribbon. Helices in the DBD that are conserved in the ALOG domain are colored red.