Structural prediction and similarity analysis of KpACE.

<p><b>(A)</b> Diagram of KpACE (not drawn to scale). <b>(B)</b> Three-dimensional structure of KpACE predicted by AlphaFold. Three putative classical His-Ser-Asp catalytic triads for hydrolysis, including H180-S185-D217, H291-S287-D248, and H370-S278-D339, were predicted <i>in silico</i> and denoted with rectangles. Bidirectional arrows indicate the domains for CBM48 and the Catalytic domain, respectively. <b>(C)</b> Similarity of KpACE (Cyan) and DmCE1B (PDB:7b6b) (Red). <b>(D)</b> The conserved residue H180. <b>(E)</b> The conserved H370-S278-D339 of KpACE (Cyan) with the catalytic triad (H638-S542-E606) of DmCE1B (Red). <b>(F)</b> Multisequence alignment of KpACE and its four homologues. Secondary structural elements of the closest homologue DmCE1B (PDB: 7b6b), a carbohydrate esterase from <i>Dysgonomonas mossii</i>, are shown above the alignment. Additional protein sequences are obtained from acetylesterase/feruloylesterase axe1-6A (AXFA_PRER2) from <i>Prevotella ruminicola</i>, acetyl xylan esterase (Bil1033-CE1) from <i>Bacteroides intestinalis</i>, and feruloyl esterase (Bil1039-CE1) from <i>Bacteroides intestinalis</i>. The catalytic triad (H638-S542-E606) of DmCE1B and conserved residues of Histidine of KpACE are indicated by green and black arrows, respectively. The alignment was created in Clustal Omega and visualized using Espript 3.0 [<a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1012675#ppat.1012675.ref001" target="_blank">1</a>, <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1012675#ppat.1012675.ref002" target="_blank">2</a>]. Conserved amino acid residues are displayed as red text on a white background with a blue border. Identical amino acid residues between sequences are displayed in white text on a red background with a blue border.</p> <p>(PDF)</p>