Figure 6.

Schematic representation of the cell wall changes occurring in the ugtP mutant. (A) The genetic evidence in this work suggests that in comparison to wild type cells (left panel), cells lacking UgtP (right panel) showed lower CwlO activity, an increase in the PG precursor levels resulting in an upturn in PG synthesis and an increase in the LytE endopeptidase activity. These results support the idea that the ugtP mutant maintain its cell wall integrity and rod-shape by balancing the increased PG synthesis (PBP1) and hydrolysis (LytE). A representation of the proteins involved in peripheral PG synthesis or hydrolysis in wild type cells and the mutants studied in this work are shown in panels (B–E). Dark coloured boxes represent functioning proteins and light coloured boxes represent malfunctioning proteins. (B) BSB1 cells had functional proteins resulting in balanced PG synthesis and hydrolysis. (C) ΔugtP cells exhibited a malfunction in several proteins involved in PG synthesis and/or hydrolysis, such that the cell maintains a healthy balance between PG synthesis and hydrolysis. (D) ΔugtP ΔlytE cells and (E) ΔugtP ΔponA cells showed a malfunction in several proteins however, these mutants exhibited a misbalance in PG synthesis and/or hydrolysis resulting in loss of rod-shape and cell death. Therefore, a balanced synthesis and hydrolysis, potentially by the same cytoskeleton system, is important for PG synthesis and cell shape.