MreB Actin-Mediated Segregation of a Specific Region of a Bacterial Chromosome

Gitai, Zemer; Dye, Natalie A.; Reisenauer, Ann; Wachi, Masaaki; Shapiro, Lucy

doi:10.1016/j.cell.2005.01.007

Cited by 360 publications

(505 citation statements)

References 51 publications

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“…As the concentration of A22 is increased, MreB becomes localized to the membrane and more fluorescence is found in the cytoplasm. These results are consistent with previous work showing that MreB bound to A22 weakens interprotofilament contacts, thus decreasing the stability of MreB polymers (27,28).…”

Section: Mreb Polymers In A22-treated Cells and The Effect Of A22 On supporting

confidence: 93%

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MreB Orientation Correlates with Cell Diameter in Escherichia coli

Ouzounov

Nguyen

Bratton

et al. 2016

Biophysical Journal

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127

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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 5 30 nm to 1700 5 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.

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Section: Mreb Polymers In A22-treated Cells and The Effect Of A22 On supporting

confidence: 93%

“…A22 has been shown to inhibit rod shape through a specific interaction with MreB (27,28). Growing E. coli in the presence of different sublethal concentrations of A22 resulted in the growth of cells with varying steady-state cell diameters (Fig.…”

Section: Generating Different Cell Shapes By Perturbing Mrebmentioning

confidence: 99%

MreB Orientation Correlates with Cell Diameter in Escherichia coli

Ouzounov

Nguyen

Bratton

et al. 2016

Biophysical Journal

Self Cite

127

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“…In all cases examined, one common function is the maintenance of cell shape. In at least some species, MreB also plays a role in chromosome separation, (67,68) but this likely evolved later than the simpler mechanical function. As with FtsZ, I would suggest that the mechanical function of MreB for cell shape was optimized early, and that the ∼40% sequence identity represents the limit of the divergence that is consistent with maintaining this function in different species.…”

Section: Conservation Of Mrebs and The Divergence Of Actinmentioning

confidence: 99%

Evolution of the cytoskeleton

2007

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SummaryThe eukaryotic cytoskeleton appears to have evolved from ancestral precursors related to prokaryotic FtsZ and MreB. FtsZ and MreB show 40−50% sequence identity across different bacterial and archaeal species. Here I suggest that this represents the limit of divergence that is consistent with maintaining their functions for cytokinesis and cell shape. Previous analyses have noted that tubulin and actin are highly conserved across eukaryotic species, but so divergent from their prokaryotic relatives as to be hardly recognizable from sequence comparisons. One suggestion for this extreme divergence of tubulin and actin is that it occurred as they evolved very different functions from FtsZ and MreB. I will present new arguments favoring this suggestion, and speculate on pathways. Moreover, the extreme conservation of tubulin and actin across eukaryotic species is not due to an intrinsic lack of variability, but is attributed to their acquisition of elaborate mechanisms for assembly dynamics and their interactions with multiple motor and binding proteins. A new structure-based sequence alignment identifies amino acids that are conserved from FtsZ to tubulins. The highly conserved amino acids are not those forming the subunit core or protofilament interface, but those involved in binding and hydrolysis of GTP. Historical introduction Discoveries of the prokaryotic cytoskeletonBefore 1990, the cytoskeleton was thought to have evolved only in eukaryotes. Relatives or homologs of actin, tubulin or intermediate filaments were unknown in bacteria or archaea. There were sporadic reports of candidates for bacterial actin and tubulin in the 1970s and 1980s but, apart from some intriguing images of microtubules in certain bacteria,(1) these turned out to be wrong and/or were not followed up.The first suggestions of a bacterial homolog of tubulin appeared in 1992. Three groups independently discovered that the bacterial cell division protein FtsZ bound and hydrolyzed GTP, as does tubulin, and had a seven-amino-acid sequence, GGGTGTG, virtually identical to the "tubulin signature sequence".(2-4) Mukherjee and Lutkenhaus(37) then extended the sequence alignment to find a dozen additional amino acids that were completely conserved in FtsZ and in α, β and γ tubulins. They also showed that FtsZ assembled in vitro into filamentous structures. Erickson et al. (5) found that FtsZ assembled into protofilaments that could adopt two conformations, straight and curved, similar to the straight protofilaments of the microtubule wall and the tubulin rings that peel away from microtubules during disassembly. Any question of homology was resolved when tubulin and FtsZ were found to have virtually identical structures at the level of protein folding.(6,7)If one looks for bacterial relatives of tubulin or actin using a simple computer search for sequence similarity, nothing will be found. In 1992 Bork et al.(8) used a sophisticated structurebased sequence alignment, and they discovered that bacteria did have genes related to actin. Actin is...

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“…More definitive evidence that the actin cytoskeleton actively promotes DNA segregation in at least a subgroup of bacteria comes from recent study performed in C. crescentus. Gitai et al [2005] established that a novel antibiotic, A22 [Iwai et al, 2002], specifically targets the ATPbinding site of MreB, thereby leading to nearly instantaneous disassembly of the spiral-like filaments after addition to the culture. In cells treated with A22, DNA replication initiated and proceeded normally, but the newly duplicated origin regions were not separated.…”

Section: Chromosome Segregationmentioning

confidence: 99%

The bacterial nucleoid: A highly organized and dynamic structure

Thanbichler

Wang

Shapiro

2005

J of Cellular Biochemistry

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122

101

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Recent advances in bacterial cell biology have revealed unanticipated structural and functional complexity, reminiscent of eukaryotic cells. Particular progress has been made in understanding the structure, replication, and segregation of the bacterial chromosome. It emerged that multiple mechanisms cooperate to establish a dynamic assembly of supercoiled domains, which are stacked in consecutive order to adopt a defined higher-level organization. The position of genetic loci on the chromosome is thereby linearly correlated with their position in the cell. SMC complexes and histone-like proteins continuously remodel the nucleoid to reconcile chromatin compaction with DNA replication and gene regulation. Moreover, active transport processes ensure the efficient segregation of sister chromosomes and the faithful restoration of nucleoid organization while DNA replication and condensation are in progress.

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MreB Actin-Mediated Segregation of a Specific Region of a Bacterial Chromosome

Cited by 360 publications

References 51 publications

MreB Orientation Correlates with Cell Diameter in Escherichia coli

MreB Orientation Correlates with Cell Diameter in Escherichia coli

Evolution of the cytoskeleton

The bacterial nucleoid: A highly organized and dynamic structure

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