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Figure 3
Sequence and structure comparison of MtHigA2. (a) Sequence comparison of MtHigA2 with the related proteins MtHigA3 (40% sequence identity), MtHigA1 (28% sequence identity), E. coli HipB (19% sequence identity) and V. vulnificus transcription factor (22% sequence identity). Three parts of MtHigA2 (the N-terminal autocleavage region, α-helix bundle and C-terminal β-lid) are coloured with yellow, blue and green backgrounds. The four monomers from form I, the four monomers from form II and the five monomers from form III are aligned in the right panel. Each monomer shows a different state of the N-terminal residues, which implies that this region is intrinsically unstable and disordered. The charged MtHigA N-terminal residues are coloured with light red and light blue backgrounds. The key amino acids for DNA interaction in E. coli HipB and MtHigA3 are highlighted with a yellow background and the corresponding positive residues are coloured in the same way. The figure was constructed using ESPript (Robert & Gouet, 2014BB39). (b) Superposition of MtHigA2 with the structurally known proteins in (a). The superposition shows a similar fold, showing a conserved orientation of positively charged amino acids, which are coloured yellow in (a). However, when they are aligned based on HTH motifs, a unique linear coordination of MtHigA2 is observed. PDB codes are shown below the structures.

IUCrJ
Volume 8| Part 5| September 2021| Pages 823-832
ISSN: 2052-2525
https://doi.org/10.1107/S2052252521007715