The five most conserved motifs in Class D β-lactamases detected with MEME (Bailey and Elkan, 1994) colored from first to fifth in information content (red, yellow, green, purple, blue) on the OXA-1 structure model. The last two motifs colored in orange are only present outside a large evolutionary related group of α-, β- and γ-proteobacteria sequences. Highly conserved residues are shown with a gray sphere centered on the Cα atom. The doripenem molecule from our OXA-1 model is shown in stick form.