RNA polymerases in strict endosymbiont bacteria with extreme genome reduction show distinct erosions that might result in limited and differential promoter recognition
Fig 7
Structural comparison between the E. coli and the Candidatus Hodgkinia TETUND2 α-subunits.
a) 3-D structure of monomers and b) for homodimers of the α-NTD subunit in E. coli (4YLP). c) 3-D model of α-subunit monomer in Candidatus Hodgkinia TETUND2 with the amino acids under positive selection in red and the H116 in green. d), e), and f) show predictions of the α-subunit homodimer formation in Candidatus Hodgkinia TETUND2. The amino acids under positive selection are in red and yellow in each monomer, H116 in green. White regions in a) and b) structures are not conserved in the α-subunit of Candidatus Hodgkinia TETUND2. The amino acids in blue, dark, and turquoise are necessary for the RNAP core formation. In the b) structure, the dark green amino acids are the same as the blue in a). S1 and S2 indicate subdomains 1 and 2 in the α-NTD. Moreover, the letter A and B correspond to each monomer that forms the homodimer.