Figure 4.

High-scoring sequence matches to the ligand-binding residue set of LacI, showing that residues in contact with IPTG are largely preserved for the sequence that has been annotated as “LacI” in Klebsiella pneumoniae and for ORF 3367755. A simple scoring scheme was used to order the output on the basis of subset and whole-domain sequence similarity. Numbers below the alignment indicate the interacting hydroxyl groups of the IPTG structure (below). Columns that are not highlighted correspond to residues that have a side-chain atom ≤4.5 Å from IPTG, but which do not appear to make direct contact. Asterisks indicate less plausible residue substitutions in the binding site (see text).