scholarly journals Two FtsZ proteins orchestrate archaeal cell division through distinct functions in ring assembly and constriction

2020 ◽  
Author(s):  
Yan Liao ◽  
Solenne Ithurbide ◽  
Christian Evenhuis ◽  
Jan Löwe ◽  
Iain G. Duggin
Keyword(s):  
Cell Division ◽  
Dna Replication ◽  
Division Ring ◽  
Cell Shape ◽  
Haloferax Volcanii ◽  
Wall Ingrowth ◽  
Ring Assembly ◽  
Division Mechanism

The tubulin homolog FtsZ assembles a cytokinetic ring in bacteria and plays a key role in the machinery that constricts to divide the cells. Many archaea encode two FtsZ proteins from distinct families, FtsZ1 and FtsZ2, of previously unclear functions. Here we show that Haloferax volcanii cannot divide properly without either or both, but DNA replication continues, and cells proliferate in alternative ways via remarkable envelope plasticity. FtsZ1 and FtsZ2 co-localize to form the dynamic division ring. However, FtsZ1 can assemble rings independently of FtsZ2, and stabilizes FtsZ2 in the ring, whereas FtsZ2 functions primarily in the constriction mechanism. FtsZ1 also influenced cell shape suggesting it forms a hub-like platform at midcell for the assembly of shape-related systems too. Both FtsZ1 and FtsZ2 are widespread in archaea with a single S-layer envelope, but archaea with a pseudomurein wall and division septum only have FtsZ1. FtsZ1 is therefore likely to provide a fundamental recruitment role in diverse archaea, and FtsZ2 is required for constriction of a flexible S-layer envelope, where an internal constriction force might dominate the division mechanism, in contrast to the single-FtsZ bacteria and archaea that divide primarily by wall ingrowth.

scholarly journals Cell division in the archaeon Haloferax volcanii relies on two FtsZ proteins with distinct functions in division ring assembly and constriction

2021 ◽  
Vol 6 (5) ◽  
pp. 594-605
Author(s):  
Yan Liao ◽  
Solenne Ithurbide ◽  
Christian Evenhuis ◽  
Jan Löwe ◽  
Iain G. Duggin
Keyword(s):  
Cell Division ◽  
Division Ring ◽  
Haloferax Volcanii ◽  
Ring Assembly

scholarly journals The proteasome controls ESCRT-III–mediated cell division in an archaeon

Science ◽  
2020 ◽  
Vol 369 (6504) ◽  
pp. eaaz2532 ◽  
Author(s):  
Gabriel Tarrason Risa ◽  
Fredrik Hurtig ◽  
Sian Bray ◽  
Anne E. Hafner ◽  
Lena Harker-Kirschneck ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Dna Replication ◽  
Division Ring ◽  
Cell Cycle Control ◽  
Sulfolobus Acidocaldarius ◽  
Cyclin Dependent Kinase ◽  
Membrane Remodeling

Sulfolobus acidocaldarius is the closest experimentally tractable archaeal relative of eukaryotes and, despite lacking obvious cyclin-dependent kinase and cyclin homologs, has an ordered eukaryote-like cell cycle with distinct phases of DNA replication and division. Here, in exploring the mechanism of cell division in S. acidocaldarius, we identify a role for the archaeal proteasome in regulating the transition from the end of one cell cycle to the beginning of the next. Further, we identify the archaeal ESCRT-III homolog, CdvB, as a key target of the proteasome and show that its degradation triggers division by allowing constriction of the CdvB1:CdvB2 ESCRT-III division ring. These findings offer a minimal mechanism for ESCRT-III–mediated membrane remodeling and point to a conserved role for the proteasome in eukaryotic and archaeal cell cycle control.

scholarly journals cdc12p, a Protein Required for Cytokinesis in Fission Yeast, Is a Component of the Cell Division Ring and Interacts with Profilin

1997 ◽  
Vol 137 (1) ◽  
pp. 169-182 ◽  
Author(s):  
Fred Chang ◽  
David Drubin ◽  
Paul Nurse
Keyword(s):  
Cell Division ◽  
Fission Yeast ◽  
Division Ring ◽  
Genetic Interaction ◽  
Essential Gene ◽  
Single Point ◽  
Actin Ring ◽  
Ring Assembly ◽  
Mutant Cells

As in many other eukaryotic cells, cell division in fission yeast depends on the assembly of an actin ring that circumscribes the middle of the cell. Schizosaccharomyces pombe cdc12 is an essential gene necessary for actin ring assembly and septum formation. Here we show that cdc12p is a member of a family of proteins including Drosophila diaphanous, Saccharomyces cerevisiae BNI1, and S. pombe fus1, which are involved in cytokinesis or other actin-mediated processes. Using indirect immunofluorescence, we show that cdc12p is located in the cell division ring and not in other actin structures. When overexpressed, cdc12p is located at a medial spot in interphase that anticipates the future ring site. cdc12p localization is altered in actin ring mutants. cdc8 (tropomyosin homologue), cdc3 (profilin homologue), and cdc15 mutants exhibit no specific cdc12p staining during mitosis. cdc4 mutant cells exhibit a medial cortical cdc12p spot in place of a ring. mid1 mutant cells generally exhibit a cdc12p spot with a single cdc12p strand extending in a random direction. Based on these patterns, we present a model in which ring assembly originates from a single point on the cortex and in which a molecular pathway for the functions of cytokinesis proteins is suggested. Finally, we found that cdc12 and cdc3 mutants show a syntheticlethal genetic interaction, and a proline-rich domain of cdc12p binds directly to profilin cdc3p in vitro, suggesting that one function of cdc12p in ring assembly is to bind profilin.

scholarly journals Regulation of Cell Division in Bacteria by Monitoring Genome Integrity and DNA Replication Status

2019 ◽  
Vol 202 (2) ◽  
Author(s):  
Peter E. Burby ◽  
Lyle A. Simmons
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Cell Division ◽  
Dna Replication ◽  
Cell Cycle Progression ◽  
Genome Instability ◽  
Sos Response ◽  
Bacterial Cells ◽  
Cycle Progression ◽  
Content Type

ABSTRACT All organisms regulate cell cycle progression by coordinating cell division with DNA replication status. In eukaryotes, DNA damage or problems with replication fork progression induce the DNA damage response (DDR), causing cyclin-dependent kinases to remain active, preventing further cell cycle progression until replication and repair are complete. In bacteria, cell division is coordinated with chromosome segregation, preventing cell division ring formation over the nucleoid in a process termed nucleoid occlusion. In addition to nucleoid occlusion, bacteria induce the SOS response after replication forks encounter DNA damage or impediments that slow or block their progression. During SOS induction, Escherichia coli expresses a cytoplasmic protein, SulA, that inhibits cell division by directly binding FtsZ. After the SOS response is turned off, SulA is degraded by Lon protease, allowing for cell division to resume. Recently, it has become clear that SulA is restricted to bacteria closely related to E. coli and that most bacteria enforce the DNA damage checkpoint by expressing a small integral membrane protein. Resumption of cell division is then mediated by membrane-bound proteases that cleave the cell division inhibitor. Further, many bacterial cells have mechanisms to inhibit cell division that are regulated independently from the canonical LexA-mediated SOS response. In this review, we discuss several pathways used by bacteria to prevent cell division from occurring when genome instability is detected or before the chromosome has been fully replicated and segregated.

The role of microtubules in chick blastoderm expansion—a quantitative study using colchicine

Development ◽  
1975 ◽  
Vol 34 (1) ◽  
pp. 265-277
Author(s):  
J. R. Downie
Keyword(s):  
Cell Division ◽  
Cell Shape ◽  
Shape Change ◽  
Cell Sheet ◽  
Cell Movement ◽  
Vitelline Membrane ◽  
General Context ◽  
Chick Blastoderm ◽  
Cell Shape Change ◽  
Cytoplasmic Microtubules

Since their discovery, cytoplasmic microtubules have been much studied in the context of cell movement and cell shape change. Much of the work has used drugs, particularly colchicine and its relatives, which break down microtubules — the so-called anti-tubulins. Colchicine inhibits the orientated movements of many cell types in vitro, and disrupts cell shape change in several morphogenetic situations. The investigation reported here used chick blastoderm expansion in New culture in an attempt to quantify the colchicine effect on orientated cell movement. However, although colchicine could halt blastoderm expansion entirely, a simple interpretation was not possible. (1) Colchicine at concentrations capable of blocking mitosis, and of disrupting all or most of the cytoplasmic microtubules of the cells studied, inhibited blastoderm expansion, often resulting in an overall retraction of the cell sheet. (2) Though blastoderm expansion does normally involve considerable cell proliferation, the colchicine effect could not be ascribed to a block on cell division since aminopterin, which stops cell division without affecting microtubules, did not inhibit expansion. (3) Blastoderm expansion is effected by the locomotion of a specialized band of edge cells at the blastoderm periphery. These are the only cells normally attached to the vitelline membrane — the substrate for expansion. When most of the blastoderm was excised, leaving the band of edge cells, and the cultures then treated with colchicine, expansion occurred normally. The colchicine effect on blastoderm expansion could not therefore be ascribed to a direct effect on the edge cells. (4) An alternative site of action of the drug is the remaining cells of the blastoderm. These normally become progressively flatter as expansion proceeds. If flattening in these cells is even partially dependent on their cytoplasmic microtubules, disruption of these microtubules might result in the inherent contractility of the cells resisting and eventually halting edge cell migration. That cell shape in these cells is dependent on microtubules was demonstrated by treating flat blastoderm fragments with colchicine. On incubation, the area occupied by these fragments decreased by 25–30 % more than controls. The significance of these results in the general context of orientated cell movements and cell shape determination is discussed, with particular emphasis on the analogous system of Fundulus epiboly.

Changes of the DNA content of differentiating and adult macronuclei of the ciliate Loxodes magnus (Karyorelictida)

1980 ◽  
Vol 44 (1) ◽  
pp. 375-394
Author(s):  
N.N. Bobyleva ◽  
B.N. Kudrjavtsev ◽  
I.B. Raikov
Keyword(s):  
Cell Division ◽  
Dna Replication ◽  
Hydrochloric Acid ◽  
Dna Synthesis ◽  
Acid Hydrolysis ◽  
Gene Amplification ◽  
Dna Content

The DNA content of isolated micronuclei, differentiating macronuclei (macronuclear Anlagen), and adult macronuclei of Loxodes magnus was measured cytofluorimetrically in preparations stained with a Schiff-type reagent, auramine-SO2, following hydrochloric acid hydrolysis. The DNA content of the youngest macronuclear Anlagen proved to be the same as that of telophasic micronuclei (2 c). The Anlagen thus differentiate from micronuclei which are still in G1. The quantity of DNA in the macronuclear Anlagen thereafter rises to the 4-c level, simultaneously with DNA replication in the micronuclei which immediately follows mitosis. In non-dividing animals most micronuclei are already in G2. Adult macronuclei here contain on average 1.5 times more DNA than the micronuclei; their DNA content is about 5–6 c (in some individual nuclei, up to 10 c). These data are consistent with autoradiographic evidence indicating a weak DNA synthesis in the macronuclei of Loxodes and make likely the existence of partial DNA replication (e.g. gene amplification) in the macronuclei. The DNA content of adult macronuclei isolated from dividing animals proved to be significantly smaller than that of macronuclei isolated from non-dividing specimens of the same clone. In 3 clones studied, the former value amounted on average to 71–79, 78 and 95% of the latter, respectively. This drop of DNA content cannot be explained by ‘dilution’ of the old macronuclei with newly formed ones. The quantity of DNA in adult macronuclei thus seems to undergo cyclical changes correlated with cytokinesis, despite the fact that, in Loxodes magnus, the macronuclei themselves never divide and are simply segregated at every cell division. The macronuclei of Loxodes can be termed paradiploid or hyperdiploid.

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