DIFFERENTIATION IN THE <i>CAULOBACTER</i> CELL CYCLE

Shapiro, Lucille

doi:10.1146/annurev.mi.30.100176.002113

Cited by 110 publications

(79 citation statements)

References 65 publications

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“…We specifically focused on C. crescentus, because Caulobacter MreB is essential and regulates cell morphology, chromosome segregation, and polar protein localization (8)(9)(10). Caulobacter also has an inherently asymmetric life cycle: With each cell cycle, it constructs a cellular extension (known as a stalk) at one pole of the cell [stalked (ST) pole] and a flagellum at the opposite pole (swarmer pole), such that division gives rise to two daughter cells that differ in polar morphology, size, and cell fate (23). With each cell cycle, Caulobacter MreB forms a dynamic spiral that condenses into a ring positioned at the future division plane and then expands back into a lengthwise spiral (8).…”

mentioning

confidence: 99%

Single molecules of the bacterial actin MreB undergo directed treadmilling motion in Caulobacter crescentus

Kim

Gitai

Kinkhabwala

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

194

241

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The actin cytoskeleton represents a key regulator of multiple essential cellular functions in both eukaryotes and prokaryotes. In eukaryotes, these functions depend on the orchestrated dynamics of actin filament assembly and disassembly. However, the dynamics of the bacterial actin homolog MreB have yet to be examined in vivo. In this study, we observed the motion of single fluorescent MreB-yellow fluorescent protein fusions in living Caulobacter cells in a background of unlabeled MreB. With time-lapse imaging, polymerized MreB [filamentous MreB (fMreB)] and unpolymerized MreB [globular MreB (gMreB)] monomers could be distinguished: gMreB showed fast motion that was characteristic of Brownian diffusion, whereas the labeled molecules in fMreB displayed slow, directed motion. This directional movement of labeled MreB in the growing polymer provides an indication that, like actin, MreB monomers treadmill through MreB filaments by preferential polymerization at one filament end and depolymerization at the other filament end. From these data, we extract several characteristics of single MreB filaments, including that they are, on average, much shorter than the cell length and that the direction of their polarized assembly seems to be independent of the overall cellular polarity. Thus, MreB, like actin, exhibits treadmilling behavior in vivo, and the long MreB structures that have been visualized in multiple bacterial species seem to represent bundles of short filaments that lack a uniform global polarity.bacteria ͉ cytoskeleton ͉ single-molecule fluorescence I n both eukaryotic and prokaryotic cells, actin mediates essential cellular processes. A quantitative understanding of the kinetic dynamics and ultrastructural architecture of actin's polymerized filaments has helped elucidate the mechanisms by which eukaryotic actin functions. For example, high-resolution imaging and the in vivo and in vitro dissection of the kinetics of its assembly have demonstrated how actin polymerization at the tips of a rigid, crosslinked actin meshwork can drive cell motility at the leading edge of Dictyostelium (1, 2). In budding yeast, the polarized assembly of actin cables provides both a road and direction signs for the directed transport of proteins to the tip of growing buds (3).There are two known bacterial actin homologs, the widely conserved, chromosomally encoded MreB family of proteins and the plasmid-specific ParM family of proteins. ParM functions to partition plasmid DNA by polymerizing in between two sister plasmids, thereby generating a tension rod that physically pushes them apart (4). MreB is essential in most bacteria and has been shown to form a lengthwise spiral that contributes to cell shape, chromosome segregation, and polar protein localization in multiple species, including Caulobacter crescentus, Escherichia coli, and Bacillus subtilis (5-10). The mechanism by which MreB executes its functions remains largely unknown (11).In vitro studies of the dynamics of eukaryotic actin filament assembly have demonstrated th...

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mentioning

confidence: 99%

Single molecules of the bacterial actin MreB undergo directed treadmilling motion in Caulobacter crescentus

Kim

Gitai

Kinkhabwala

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

194

241

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“…E. coli, Sulmonella tlphirnuriurn, Caulohacter crescentus, My.~ococcus xanthus, Beneckea hurreyi and A Icaligenes cwtrophuv (Pastan & Adhya. 1976;Shapiro, 1976;Orlowski, 1980;Nealson & Hastings, 1979;Tait et al, 1981). In this study, ["]CAMP binding activity was detected in several strains of B. pertussis and, on average, was approximately half that obtained from the wild-type E. coli Crp+ and approximately four times that obtained for E. coli crp.…”

Section: Discussionmentioning

confidence: 62%

Adenylate Cyclase Activity During Phenotypic Variation of Bordetella pertussis

Brownlie¹,

Coote²,

Parton³

1985

Microbiology

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“…Caulobacter may prevent the release of such population-endangering factors by killing severely damaged cells, thereby sacrificing a small number of damaged bacteria rather than releasing a large number of agents that could threaten the entire population. The potential role for BapE in eliminating phage induction may thus explain why no prophages have been found in wild-type Caulobacter strains (12).…”

Section: Discussionmentioning

confidence: 99%

“…1 A and B). Cell death is surprising given that SOS-induced bacterial lysis has generally been associated with prophage induction (10,11), but Caulobacter laboratory strains do not host any temperate phage (12). Therefore, we tested the possibility that Caulobacter induced an apoptotic-like cell death pathway by staining these cells with two markers of apoptotic death, DIBAC4(3), a voltage-sensitive fluorescent dye that is stimulated by the membrane depolarization associated with eukaryotic apoptosis (13,14), and TUNEL, which labels the ends of fragmented chromosomes and is also characteristic of eukaryotic apoptosis (15).…”

Section: Dna Damage Stimulates Apoptotic-like Death In Caulobactermentioning

confidence: 99%

BapE DNA endonuclease induces an apoptotic-like response to DNA damage in Caulobacter

Bos

Yakhnina

Gitai

2012

Proc. Natl. Acad. Sci. U.S.A.

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In the presence of extensive DNA damage, eukaryotes activate endonucleases to fragment their chromosomes and induce apoptotic cell death. Apoptotic-like responses have recently been described in bacteria, but primarily in specialized mutant backgrounds, and the factors responsible for DNA damage-induced chromosome fragmentation and death have not been identified. Here we find that wild-type Caulobacter cells induce apoptotic-like cell death in response to extensive DNA damage. The bacterial apoptosis endonuclease (BapE) protein is induced by damage but not involved in DNA repair itself, and mediates this cell fate decision. BapE fragments chromosomes by cleaving supercoiled DNA in a sequence-nonspecific manner, thereby perturbing chromosome integrity both in vivo and in vitro. This damage-induced chromosome fragmentation pathway resembles that of eukaryotic apoptosis. We propose that damage-induced programmed cell death can be a primary stress response for some bacterial species, providing isogenic bacterial communities with advantages similar to those that apoptosis provides to multicellular organisms.

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DIFFERENTIATION IN THE CAULOBACTER CELL CYCLE

Cited by 110 publications

References 65 publications

Single molecules of the bacterial actin MreB undergo directed treadmilling motion in Caulobacter crescentus

Single molecules of the bacterial actin MreB undergo directed treadmilling motion in Caulobacter crescentus

Adenylate Cyclase Activity During Phenotypic Variation of Bordetella pertussis

BapE DNA endonuclease induces an apoptotic-like response to DNA damage in Caulobacter

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