Fig. 1. Dimeric CopY structural model. (A) Ribbon representation of the superposition of the solution structure bundle of the L. lactis CopR DNA binding domain (salmon)17 on the crystallographic structure of S. aureus BlaI (green, DNA-binding domain; grey, regulatory domain).24 The approximate positions of the five Spn CopY Cys are indicated, with the C128–C130 pair just beyond the solved structure of the BlaI determined by a multiple sequence alignment (not shown). (B) Multiple sequence alignment of CopY proteins from different bacteria. The conserved Cys residue proposed to be involved in copper and zinc binding are highlighted with asterisks. Note that S. pneumoniae CopY only contains two of the four Cys residues near the C-terminus. The C-terminus of the L. lactis CopR DNA binding domain model (see panel A) is E74 (T69 in Spn CopY), with the last residue of the β2 strand R70 (S65 in Spn CopY). K119 in the Spn CopY sequence defines the C-terminus of the BlaI model24 shown in panel A.