Mutations in cell elongation genes mreB, mrdA and mrdB suppress the shape defect of RodZ‐deficient cells

Daisuke Shiomi,Tadasu Shini,Asao Fujiyama,Fumio Ejima,Yuji Kohara,Atsushi Toyoda,Tomoyuki Aizu,Hironori Niki

doi:10.1111/mmi.12148

Abstract

RodZ interacts with MreB and both factors are required to maintain the rod shape of Escherichia coli. The assembly of MreB into filaments regulates the subcellular arrangement of a group of enzymes that synthesizes the peptidoglycan (PG) layer. However, it is still unknown how polymerization of MreB determines the rod shape of bacterial cells. Regulatory factor(s) are likely to be involved in controlling the function and dynamics of MreB. We isolated suppressor mutations to partially recover the rod shape in rodZ deletion mutants and found that some of the suppressor mutations occurred in mreB. All of the mreB mutations were in or in the vicinity of domain IA of MreB. Those mreB mutations changed the property of MreB filaments in vivo. In addition, suppressor mutations were found in the periplasmic regions in PBP2 and RodA, encoded by mrdA and mrdB genes. Similar to MreB and RodZ, PBP2 and RodA are pivotal to the cell wall elongation process. Thus, we found that mutations in domain IA of MreB and in the periplasmic domain of PBP2 and RodA can restore growth and rod shape to ΔrodZ cells, possibly by changing the requirements of MreB in the process.

Highlights

In the 1970s, there were many attempts to identify cytoskeletal proteins in prokaryotes (Minkoff and Damadian, 1976; Beck et al, 1978; Nakamura and Watanabe, 1978; Nakamura et al, 1978)
We found that mutations in domain IA of MreB and in the periplasmic domain of PBP2 and RodA can restore growth and rod shape to DrodZ::kan prepared from JW2500 (DrodZ) cells, possibly by changing the requirements of MreB in the process
A breakthrough that led to the discovery of bacterial cytoskeletal proteins came from studies of cell division and morphology, and the gene products of ftsZ and mreB in prokaryotes are known to be structurally and functionally related to eukaryotic tubulin and actin respectively (Wachi et al, 1987; Bi and Lutkenhaus, 1991; de Boer et al, 1992; RayChaudhuri and Park, 1992; Lowe and Amos, 1998; Jones et al, 2001; van den Ent et al, 2001)