Figure 4. Analysis of the minimal binding frame of SsbB by electrophoretic mobility shift assays.

A) Determination of the minimal binding frame of one SsbB tetramer. Each binding reaction contained 1 µM (SsbB)₄ and 5 µM dT_n of different lengths (6–35 nucleotides) and was performed in SBA buffer. The reactions were analyzed by polyacrylamide gel electrophoresis and SsbB was later visualized by Coomassie staining. B) Determination of the minimal binding frame of two SsbB tetramers. The binding reaction contained 1 µM (SsbB)₄ and 0.25 µM dT_n of different lengths (67–74 nucleotides) and was performed in SBA buffer. The reactions were analyzed by polyacrylamide gel electrophoresis and SsbB was later visualized by Coomassie staining. The square (□) indicates the free SsbB tetramer, while one (*) or two (**) asterixes represent an oligonucleotide bound to one or two SsbB tetramers.