Fig. 4: MreC modulates PG formation during cell wall elongation by self-association.
From: Self-association of MreC as a regulatory signal in bacterial cell wall elongation
a Crystal structure of the MreC:PBP2 complex from H. pylori (PDB 5LP5). b closeup of the MreC:PBP2 interaction region, with the hydrophobic zipper region of MreC highlighted in magenta. MreCHp is in orange, PBP2 in gray. c overlay of the MreCPa dimer (green) onto MreCHp within the MreC:PBP2 structure reveals that the potential hydrophobic zipper of MreCPa is in close proximity to Region 3 (Glu188, Arg190). In this situation, MreC’s self-association capacity is blocked by the presence of PBP2. d, e in the absence of PBP2, Region 3 is free and MreC dimers associate into stable tetrameric forms, giving rise to higher-order structures that do not interact with PBP2. Arg175 (Region 2) is essential for interactions both in the presence and absence of PBP2. f Schematic model of MreC’s modulation of cell wall elongation. PBP2 is shown in gray, pink (anchor) and blue (head). MreC oligomers and PBP2, both contacted by MreD23, do not interact and PG biosynthesis is off. A signal, which could involve accumulation of MreC beyond a given threshold, displaces MreD and allows MreC to interact with an open form of PBP2, which in turn recognizes RodA and activates PG biosynthesis22.
