Fig. 2: Glp–FtsZ interaction.
a, Comparison of the recovery of FtsZ and Glp in co-IP (α-Scarlet) of Cglu_SepF-Scarlet and the mutant unable to bind FtsZ (SepFK125E/F131A-Scarlet). Each point corresponds to the normalized XIC intensity in each replicate for each condition, calculated as described in Methods; n = 4 biologically independent samples per condition; mean ± s.d. Statistical analysis was performed using unpaired two-sided Student’s t-test. FtsZ fold change (FC) = 6.61 (P = 0.0006); Glp FC = 2.70 (P = 0.014). See Supplementary Table 1b for corresponding analysis. b, BLI sensorgrams of Glp binding to immobilized SUMO-FtsZ. Glp concentrations range from 80 μM (dark blue) to 1.25 μM (light green) in 2-fold dilutions. c, Crystal structure of the Glp homodimer (blue and green) in complex with FtsZCTD (yellow and red). The Glp monomer is composed of 4 structural domains (labelled I–IV): domain I (residues 20–45 and 146–181), domain II (residues 46–145), domain III (residues 1–19 and 182–331) and domain IV (residues 332–417). The location of the putative active site at the distal dimer interface is indicated. d, Detailed view of Glp–FtsZ interactions. The peptide adopts a linear extended conformation, with a central kink promoted by the presence of Pro438. The C-terminal half of the peptide backbone runs roughly parallel to the Glp β-strand 360–363 and is stabilized by three intermolecular hydrogen bonds between main-chain atoms (NR362-OP438, OR362-NF440 and NA364-OF440) and by hydrophobic interactions (FtsZ Phe440 with Glp Leu343, Met361 and Leu370). On the N-terminal half, the side chains of FtsZ residues Leu435 and Val437 are anchored in a hydrophobic pocket defined by Glp residues Val338, Leu360, Tyr369 and Phe414. Residues involved in protein–protein interactions are labelled; the molecular surface of Glp shows hydrophobicity (yellow, hydrophobic; green, hydrophilic); intermolecular hydrogen bonds are shown as blue dotted lines. e, Left: the superposition of the monomers from Glp (blue) and MoeA from E. coli (pink, pdb 1g8l) reveals a pronounced conformational change from a hinge region at the interface between domain I and III. This change leads to a central open (right; Glp, blue) or closed (middle; MoeA, pink) conformation in the respective homodimers.
