Fur-like proteins are conserved among the genus Streptococcus and are close to PerR. (A) Multiple alignment of PerR protein from S. suis 05ZYH33 with the Fur family proteins PerR, Zur and Fur in B. subtilis str. 168. The DNA-binding motif is marked in the gray box. Nine conserved amino acid residues in PerR are marked with gray bottom colour. Five residues (H37, D85, H91, H93 and D104) are the candidate amino acid ligands for Fe2+ or Mn2+ and four cysteine residues (C96, C99, C136 and C139) are for Zn2+, H37 and H91 are the sites of H2O2-mediated oxidation. These amino acid residues in S. suis PerR protein are conserved except that N is taking the place of H in site 93, this change also exists in S. pyogenes. (B) A phylogenetic tree of Fur-like proteins from selected streptococci and other Gram-positive bacteria was constructed based on a multiple sequence alignment using DNAMAN. Fur-like proteins in each streptococcus are represented by the abbreviation of strain name. BS, B. subtilis 168, CA, C. acetobutylicum ATCC 824, SA, S. aureus Mu50, SAG, S. agalactiae 2603 V/R, SD, S. dysgalactiae GGS_124, SE, S. equi MGCS10565, SG, S. gordonii CH1, SM, S. mutans NN2025, SP, S. parauberis KCTC 11537, SPY, S. pyogenes M1 GAS, SS, S. suis 05ZYH33, SSG, S. sanguinis SK36, ST, S. thermophilus CNRZ1066, SU, S. uberis 0140 J.