Sequence conservation between ZitR/AdcR proteins.

<p>Multi-alignment of ZitR/AdcR protein sequences was performed using Clustal Omega server (<a href="" target="_blank"></a>) and ESPript server (<a href="" target="_blank"></a>) [<a href="" target="_blank">30</a>]. We noticed that several lactococcal proteins are erroneously annotated as ‘AdcR’ in gene/protein databases, as they share a higher homology level with ZitR proteins than to the prototypal AdcR protein from <i>S</i>. <i>pneumoniae</i> [<a href="" target="_blank">13</a>, <a href="" target="_blank">18</a>, <a href="" target="_blank">19</a>]. We therefore renamed them as ZitR proteins. The following sequences are shown: i) ZitR from <i>L</i>. <i>lactis</i> subsp. <i>cremoris</i> (Llaccre) strain MG1363 (gb |A2RNS2.1|), our lactococcal protein model [<a href="" target="_blank">15</a>, <a href="" target="_blank">16</a>]; ii) ZitR from <i>L</i>. <i>lactis</i> subsp. <i>lactis</i> (Llaclac) strain IL1403 (gb |NP_268273.1|, gb |AAK06214.1|, gb |Q9CDU5|, PDB: 5YHX [<a href="" target="_blank">21</a>]), which is identical to ZitR proteins from <i>L</i>. <i>lactis</i> subsp. <i>lactis</i> strain NCDO 2118 (gb |AII13676.1|) and subsp. <i>lactis</i> bv. <i>diacetylactis</i> (gb |KZK11188.1|), not shown; iii) ZitR (‘AdcR’) from <i>L</i>. <i>piscium</i> (Lpis) strains MKFS47 (gb |CEN27435.1|) and iv) CNCM I-4031 (gb |SCA91076.1|); v) ZitR (‘AdcR’) from <i>L</i>. <i>raffinolactis</i> (Lraf) strain 4877 (gb |CCK19333.1|); vi) ZitR (‘AdcR’) from <i>L</i>. <i>garvieae</i> (Lgar) strains DCC43 (gb |EKF52529.1|) and vii) 122061 (gb |BAV02535.1|), which is identical to the protein from strain M14 (gb |CEF51164.1|), not shown; viii) ZitR (‘AdcR’) from <i>Lactococcus</i> sp. (Lsp) strain DD01 (gb |KXT61547.1|); ix) the prototypal AdcR protein [<a href="" target="_blank">13</a>, <a href="" target="_blank">18</a>] from <i>S</i>. <i>pneumoniae</i> (Spne) strain D39 (gb |Q04I02.1|, PDB: 3TGN [<a href="" target="_blank">13</a>]); and finally x) AdcR protein from <i>S</i>. <i>pyogenes</i> strain MGAS315 (gb |AAM78676.1|), or serotype M3 (PDB: 5JLU [<a href="" target="_blank">20</a>]). Secondary structure elements of ZitR<sub>MG</sub> protein are displayed above its sequence: α-helices as medium squiggles and β-strands as arrows. ZitR<sub>MG</sub> residues shown here (see below) to belong to the dimerization interface or to the metal binding pocket (<a href="" target="_blank">Fig 2</a>) are respectively indicated by ‘d’ and ‘z’ characters below the sequences. Amino acids that appear in white characters in a red background are identical in all aligned proteins, while those in red characters and in blue frames are conserved in the majority of proteins.</p>