MreB Orientation Correlates with Cell Diameter in Escherichia coli.
Bacteria have remarkably robust cell shape control mechanisms. For example, cell diameter only varies by a few percent across a given population. The bacterial actin homolog, MreB, is necessary for establishment and maintenance of rod shape although the detailed properties of MreB that are important for shape control remained unknown. In this study, we perturb MreB in two ways: by treating cells with the polymerization-inhibiting drug A22 and by creating point mutants in mreB. These perturbations modify the steady-state diameter of cells over a wide range, from 790 ± 30 nm to 1700 ± 20 nm. To determine which properties of MreB are important for diameter control, we correlated structural characteristics of fluorescently tagged MreB polymers with cell diameter by simultaneously analyzing three-dimensional images of MreB and cell shape. Our results indicate that the helical pitch angle of MreB inversely correlates with the cell diameter of Escherichia coli. Other correlations between MreB and cell diameter are not found to be significant. These results demonstrate that the physical properties of MreB filaments are important for shape control and support a model in which MreB organizes the cell wall growth machinery to produce a chiral cell wall structure and dictate cell diameter.
Department of Molecular Biology, Princeton University, Princeton, New Jersey.
Nikolay
N
Ouzounov
Department of Physics, Princeton University, Princeton, New Jersey.
Jeffrey P
JP
Nguyen
Department of Molecular Biology, Princeton University, Princeton, New Jersey; Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey.
Benjamin P
BP
Bratton
Department of Physics, Princeton University, Princeton, New Jersey.
David
D
Jacobowitz
Department of Molecular Biology, Princeton University, Princeton, New Jersey.
Zemer
Z
Gitai
Department of Physics, Princeton University, Princeton, New Jersey; Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey. Electronic address: shaevitz@princeton.edu.
Joshua W
JW
Shaevitz
D004926:Escherichia coli / Q000737:chemistry / Q000166:cytology* / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D021621:Imaging, Three-Dimensional; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D009154:Mutation
D029968:Escherichia coli Proteins; D049452:Green Fluorescent Proteins; C078473:MreB protein, E coli