Gene organisation and structure-based sequence alignment of selected members of the avidin protein family.

<p>(A) Gene organization shown for selected avidins. The exons are shown as red boxes and the length of introns and exons are indicated. (B) Structure-based sequence alignment. The sequences of zebavidin [PDB: 4BJ8; reported here], xenavidin [PDB: 2UYW] and chicken avidin [PDB: 1AVD] are shown. Black squares: residues surrounding the bicyclic ring system of biotin; black triangles: residues around the valeric acid moiety; cyan triangles: zebavidin-specific Ala43 and Ala44 facing the valeric acid moiety of biotin; cyan background: the conserved Phe72/Phe71 of avidin/xenavidin missing from zebavidin; orange triangle: indicates the residue directly involved in biotin binding in avidin/xenavidin (Ser73/Ser72) but not in zebavidin (Lys72); asterisks: three zebavidin specific residues (Phe95, Met97 and Met114) found at IF1,2 and IF1,3 subunit interfaces; yellow background: the free cysteine (Cys75) of zebavidin. The conserved residues are indicated by the default coloring scheme of the ESPript program [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0077207#B49" target="_blank">49</a>]. The β-strands of zebavidin are numbered. TT, β-turn and α1, 3/10-helix.