Fig. 3.

Possible contributions to cell straightening. (A) Nonuniform cross-linking: Glycan chains and peptide links are shown assuming ideal ordering. Turgor pressure causes the cell to curve when the density of cross-links is different between the two sides of the cell. (B) Stress-dependent synthesis. Perpendicular stress is larger on the inner side of the cell than on the outer one with the difference linearly proportional to the curvature. Thus, dependency of local growth rate on perpendicular stress could cause cell straightening. (C) MreB-dependent synthesis. The helical structure of MreB implies that the number of strands is the same on all sides of a cell causing growth mode 2 if synthesis is proportional to the local amount of MreB. (D) Processivity-dependent straightening. Greater processivity causes longer new strands (white) to be incorporated, which in turn causes faster straightening. (E) Straightening coefficient S as a function of the processivity s₀ of the PG synthesis. The circle corresponds to the value of S = 0.57 ± 0.03 measured experimentally in C. crescentus (Fig. 2), which was used to determine the processivity 287 ± 18 nm.