Fig. 6: Conservation of residues binding 2OG and glutamine in archaeal GS.

The presented phylogenic inner tree (maximum likelihood) was constructed with the 500 closest sequences to MtGS in the RefSeq database, restricted to the domain Archaea, as well as the sequences of the bacterial GSI-α from B. subtilis, S. aureus, L. monocytogenes and P. polymyxa. The tree was colored by orders (except for Bacteria), and gray dots with different radii represent the bootstrap support of each branch. Branches containing monophyletic groups are collapsed. Sequences forming monophyletic branches are gathered and labeled by a letter. The branch containing 337 sequences belonging to Natrialbales, Halobacteriales, and Haloferacales orders is condensed as no clear monophyletic groups could have been extracted. The outer panels display the most common residues at equivalent positions involved in 2OG (Arg20, Arg88, Arg174, Arg175, and Ser191, MtGS numbering, bottom line) and glutamine (position 67 in MtGS, upper line) binding. Panels are framed and labeled with the color and letter used in the inner tree. Ala34 in MtGS is not involved in 2OG coordination, but a substitution by a bulky residue (e.g. glutamate) would hinder its fixation. The residues are colored in light or dark gray depending on whether they allow metabolite binding or not, respectively. The residue distribution for each position in each group is presented in Fig. S19, and the sequences can be found in Supplementary Data 2. The GS that are predicted to be able or unable to bind 2OG and glutamine are framed in green and red, respectively. Red dots indicate the GSI-α structurally characterized previously or in the present work.