Coupled, Circumferential Motions of the Cell Wall Synthesis Machinery and MreB Filaments in B. subtilis

Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA.
Science (Impact Factor: 33.61). 06/2011; 333(6039):222-5. DOI: 10.1126/science.1203285
Source: PubMed


Rod-shaped bacteria elongate by the action of cell wall synthesis complexes linked to underlying dynamic MreB filaments. To
understand how the movements of these filaments relate to cell wall synthesis, we characterized the dynamics of MreB and the
cell wall elongation machinery using high-precision particle tracking in Bacillus subtilis. We found that MreB and the elongation machinery moved circumferentially around the cell, perpendicular to its length, with
nearby synthesis complexes and MreB filaments moving independently in both directions. Inhibition of cell wall synthesis by
various methods blocked the movement of MreB. Thus, bacteria elongate by the uncoordinated, circumferential movements of synthetic
complexes that insert radial hoops of new peptidoglycan during their transit, possibly driving the motion of the underlying
MreB filaments.

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Available from: Ethan Clark Garner, Dec 28, 2013
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    • "After interaction with MreB, the Agl–Glt machinery together with MglA-GTP and MreB would become active and move directionally along its elusive track toward the lagging cell pole. It is unlikely that MreB itself forms the track because MreB does not appear to make continuous and polarized filaments in bacterial cells (Domínguez-Escobar et al., 2011; Garner et al., 2011; van Teeffelen et al., 2011) but instead MreB could act as a protein scaffold for assembly of the motility machinery. Recently, Nan et al. (2015) further suggested that MglA also regulates the directionality of the Agl motor; whether this is linked to the interaction with MreB remains to be explored. "

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    • "The cellular factors that contribute to cell-wall biosynthesis fall into four major classes: (1) Mur enzymes, which synthesize the building blocks of the cell wall (muropeptides) in the cytoplasm; (2) penicillin-binding proteins (PBPs), which incorporate muropeptides into the cell-wall network from outside the cytoplasmic membrane; (3) hydrolytic enzymes that cleave bonds in the cell wall (Singh et al., 2012); and (4) cytoskeletal proteins that regulate the spatiotemporal pattern of cell-wall synthesis (e.g., MreB and FtsZ). MreB is a prokaryotic actin homolog that is found in many rod-shaped bacteria and forms dynamic structures in the cytoplasm that bind the inner membrane (Domínguez-Escobar et al., 2011; Garner et al., 2011; Salje et al., 2011; van Teeffelen et al., 2011). MreB is thought to coordinate the spatial pattern of insertion of new material into the cell wall during rod-shaped elongation through protein-protein interactions. "
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    • "For localization to the cell wall, LytE interacts with the cytoskeletal protein MreBH (Carballido-López et al., 2006; Domínguez-Cuevas et al., 2013), of which the expression is downregulated in retentostat 2 only. Furthermore , the transcriptome revealed the repression in both retentostats of the genes mreD and rodZ which are part of the cell wall biosynthetic complex and involved in morphogenesis (Domínguez-Escobar et al., 2011; Garner et al., 2011; Muchová et al., 2013). "
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