Mapping DNA sequence to transcription factor binding energy in vivo
Fig 5
Mutations to LacI DNA-binding domain cause subtle changes to sequence specificity.
Mutations were made to residues 20 and 21 of LacI, both of which lie within the DNA-binding domain. The mutations Y20I and Q21A weaken the repressor-operator binding energy, while the mutation Q21M strengthens the binding energy [50]. The sequence preferences of each mutant are represented as sequence logos. Y20I exhibits minor changes to specificity in low-information regions of the binding site, and Q21A experiences a change to specificity within a high-information region of the binding site (see arrows). Specifically, Q21A prefers A at operator position 6 while the wild-type repressor prefers G at this position.