Phylogenetic analysis and domain architecture of Mtb LexA
(A) Phylogenetic tree of LexA protein sequence of 24 species. The protein sequences are clustered into four groups: Actinobacteria, Proteobacteria, Euryarchaeota, and Firmicutes that include the representatives from some of the major groups of bacteria. (B) Comparison of LexA sequences among tuberculous, non-tuberculous mycobacterial species, and model Gram-negative organism, E. coli. The first 24 amino acids extension, the N-terminal DNA binding domain, linker region, the stretch of 18 amino acids insert in the linker, and C-terminal dimerization domain are shown as a bar representation below the sequence in magenta, light blue, dark blue, yellow, and light green, respectively. DNA-binding residues chosen for mutation are shown with a brown bar representation below. Sequence alignment was done using Clustal Omega, and ESPript was used to generate the Figure. (C) Representation of constructs generated for this study is shown, and the gel picture shows purified Mtb LexA and its variants resolved and visualized on 12% SDS PAGE.