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Figure 3
MtHigA3 binds to the higBA3 promoter region at a specific sequence. (a) Organization of the higBA3 operon. The higB3 toxin gene is located upstream of the higA3 antitoxin gene. Two putative operator regions predicted by the BPROM web interface (Solovyev, 2011BB44) located at the −35 and −10 positions are shown in red letters. DNA1, which includes the −35 box, is highlighted as grey, and DNA2, which includes the −10 box, is highlighted in blue. Predicted palindromic sequences (DNA3 and DNA4) for the higBA3 gene are coloured grey. The locations of the higB and higA genes are indicated by red and blue arrows, respectively. (b) EMSA experiments of the higBA3 promoter region DNA with increasing concentrations of MtHigA3 (0, 0.1, 0.2, 0.3, 0.5 and 0.6 µM). Only DNA2 is shifted upwards with increasing MtHigA3 concentration. Band shifts are indicated by red narrows. (c) ITC measurement upon the interaction of MtHigA3 and DNA2. (Left) Graphical representation of thermodynamic parameters for the MtHigA3 and DNA2 interaction. (Right) MtHigA3 binding to DNA2 is associated with a favourable entropy change.

IUCrJ
Volume 7| Part 4| July 2020| Pages 748-760
ISSN: 2052-2525
https://doi.org/10.1107/S2052252520006466