Structure-based multiple sequence alignment of LuxS homologues.

<p>Multiple alignments of LuxS homologue from <i>S</i>. <i>suis</i> HA9801 with the related LuxS proteins. The multiple alignment was conducted using ClustalW2 (<a href="http://www.ebi.ac.uk/Tools/clustalw2/index.html" target="_blank">http://www.ebi.ac.uk/Tools/clustalw2/index.html</a>), and the figure was generated with the program ESPript 2.2 (<a href="http://espript.ibcp.fr/ESPript/cgi-bin/ESP%20ript.cgi" target="_blank">http://espript.ibcp.fr/ESPript/cgi-bin/ESP ript.cgi</a>). Sequence alignment was performed for the various LuxS sequences, which included <i>S</i>.<i>suis</i>, <i>E</i>.<i>facecium</i>, <i>H</i>.<i>pylori</i>, <i>V</i>.<i>cholerae</i>, <i>V</i>.<i>harveyi</i>, <i>E</i>.<i>coli</i>, <i>S</i>.<i>enterica</i>, <i>N</i>.<i>meningitidis</i>, <i>A</i>.<i>pleuropneumoniae</i>, <i>H</i>.<i>parasuis</i>, <i>H</i>.<i>influenzae</i>, <i>C</i>.<i>gracilis</i>, <i>C</i>.<i>jejuni</i>, <i>B</i>.<i>cereus</i>, <i>B</i>.<i>subtilis</i>. The secondary structure of the SS LuxS protein is shown in top. α: α-helix; β: β-sheet; T: β-turns/coils. Three conserved zinc-binding sites (His57, His61, and Cys127) are indicated with black triangles. A critical amino acid G81 was also very conserved (highlighted with an arrow), which was recently found to be one of the important residues in the active site for AI-2 production in <i>Campylobacter jejuni</i> (Plummer et al., 2011). The Cys82 is the catalytic active residue of the LuxS protein. The distinct residues are indicated by labeling with black stars.