scholarly journals The bacterial actin-like cell division protein FtsA forms curved antiparallel double filaments upon binding of FtsN

2021 ◽  
Author(s):  
Tim Nierhaus ◽  
Stephen H McLaughlin ◽  
Frank Bürmann ◽  
Danguole Kureisaite-Ciziene ◽  
Sarah Maslen ◽  
...  
Keyword(s):  
Activation Mechanism ◽  
Lipid Monolayers ◽  
Site Specific ◽  
Division Plane ◽  
Curvature Sensing ◽  
E Coli ◽  
Z Ring ◽  
Cell Division Protein ◽  
Concentrate Cell

Cell growth and division of walled bacteria depend on the synthesis and remodelling of peptidoglycan (PG). These activities are carried out by two multiprotein complexes, the elongasome and the divisome during cell elongation and division, respectively. Filaments of tubulin-like FtsZ form the cytoplasmic scaffold for divisome assembly, the Z-ring. In E. coli, the actin homologue FtsA anchors the Z-ring to the membrane and recruits downstream divisome components, including bitopic FtsN. FtsN is recruited late and activates the periplasmic PG synthase FtsWI. To start unravelling the activation mechanism involving FtsA and FtsN, we showed that E. coli FtsA forms antiparallel double filaments on lipid monolayers when also binding FtsN's cytoplasmic tail, and that Vibrio maritimus FtsA crystallised as an equivalent double filament. We structurally located the FtsA-FtsN interaction site in FtsA's IA-IC interdomain cleft and confirmed FtsA double filament formation in vivo using site-specific cysteine cross-linking. FtsA-FtsN double filaments reconstituted on and in liposomes preferred negative Gaussian curvature, as was previously shown for the elongasome's actin, MreB. MreB filaments serve as curvature-sensing "rudders", orienting insertion of PG around the cell's circumference. We propose that curved antiparallel FtsA double filaments function similarly in the divisome: FtsA filaments, together with dynamic FtsZ filaments orient and concentrate cell-constricting septal PG synthesis in the division plane.

scholarly journals The Escherichia coli Fis Protein Stimulates Bacteriophage λ Integrative Recombination In Vitro

2003 ◽  
Vol 185 (10) ◽  
pp. 3076-3080 ◽  
Author(s):  
Dominic Esposito ◽  
Gary F. Gerard
Keyword(s):  
Escherichia Coli ◽  
Host Cell ◽  
Essential Role ◽  
Bacteriophage Λ ◽  
Site Specific ◽  
Site Specific Recombination ◽  
E Coli ◽  
In Vivo Recombination

ABSTRACT The Escherichia coli nucleoid-associated protein Fis was previously shown to be involved in bacteriophage lambda site-specific recombination in vivo, enhancing the levels of both integrative recombination and excisive recombination. While purified Fis protein was shown to stimulate in vitro excision, Fis appeared to have no effect on in vitro integration reactions even though a 15-fold drop in lysogenization frequency had previously been observed in fis mutants. We demonstrate here that E. coli Fis protein does stimulate integrative lambda recombination in vitro but only under specific conditions which likely mimic natural in vivo recombination more closely than the standard conditions used in vitro. In the presence of suboptimal concentrations of Int protein, Fis stimulates the rate of integrative recombination significantly. In addition, Fis enhances the recombination of substrates with nonstandard topologies which may be more relevant to the process of in vivo phage lambda recombination. These data support the hypothesis that Fis may play an essential role in lambda recombination in the host cell.

scholarly journals Architecture of the ring formed by the tubulin homologue FtsZ in bacterial cell division

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Piotr Szwedziak ◽  
Qing Wang ◽  
Tanmay A M Bharat ◽  
Matthew Tsim ◽  
Jan Löwe
Keyword(s):  
Cell Division ◽  
Molecular Model ◽  
Three Dimensional ◽  
Bacterial Cell Division ◽  
Electron Cryomicroscopy ◽  
E Coli ◽  
Ftsz Ring ◽  
Z Ring

Membrane constriction is a prerequisite for cell division. The most common membrane constriction system in prokaryotes is based on the tubulin homologue FtsZ, whose filaments in E. coli are anchored to the membrane by FtsA and enable the formation of the Z-ring and divisome. The precise architecture of the FtsZ ring has remained enigmatic. In this study, we report three-dimensional arrangements of FtsZ and FtsA filaments in C. crescentus and E. coli cells and inside constricting liposomes by means of electron cryomicroscopy and cryotomography. In vivo and in vitro, the Z-ring is composed of a small, single-layered band of filaments parallel to the membrane, creating a continuous ring through lateral filament contacts. Visualisation of the in vitro reconstituted constrictions as well as a complete tracing of the helical paths of the filaments with a molecular model favour a mechanism of FtsZ-based membrane constriction that is likely to be accompanied by filament sliding.

scholarly journals Investigations of human myosin VI targeting using optogenetically controlled cargo loading

2017 ◽  
Vol 114 (9) ◽  
pp. E1607-E1616 ◽  
Author(s):  
Alexander R. French ◽  
Tobin R. Sosnick ◽  
Ronald S. Rock
Keyword(s):  
Avena Sativa ◽  
Activation Mechanism ◽  
Myosin Vi ◽  
Site Specific ◽  
Specific Location ◽  
Cargo Protein ◽  
Specific Manner ◽  
A Site

Myosins play countless critical roles in the cell, each requiring it to be activated at a specific location and time. To control myosin VI with this specificity, we created an optogenetic tool for activating myosin VI by fusing the light-sensitive Avena sativa phototropin1 LOV2 domain to a peptide from Dab2 (LOVDab), a myosin VI cargo protein. Our approach harnesses the native targeting and activation mechanism of myosin VI, allowing direct inferences on myosin VI function. LOVDab robustly recruits human full-length myosin VI to various organelles in vivo and hinders peroxisome motion in a light-controllable manner. LOVDab also activates myosin VI in an in vitro gliding filament assay. Our data suggest that protein and lipid cargoes cooperate to activate myosin VI, allowing myosin VI to integrate Ca2+, lipid, and protein cargo signals in the cell to deploy in a site-specific manner.

scholarly journals The Stress-Active Cell Division Protein ZapE Alters FtsZ Filament Architecture to Facilitate Division in Escherichia coli

2021 ◽  
Vol 12 ◽  
Author(s):  
Eric C. DiBiasio ◽  
Rebecca A. Dickinson ◽  
Catherine E. Trebino ◽  
Colby N. Ferreira ◽  
Josiah J. Morrison ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cell Division ◽  
High Temperature ◽  
Environmental Stress ◽  
Atp Hydrolysis ◽  
Major Protein ◽  
Bacterial Cells ◽  
Z Ring ◽  
Cell Division Protein

During pathogenic infections, bacterial cells experience environmental stress conditions, including low oxygen and thermal stress. Bacterial cells proliferate during infection and divide by a mechanism characterized by the assembly of a large cytoskeletal structure at the division site called the Z-ring. The major protein constituting the Z-ring is FtsZ, a tubulin homolog and GTPase that utilizes the nucleotide to assemble into dynamic polymers. In Escherichia coli, many cell division proteins interact with FtsZ and modulate Z-ring assembly, while others direct cell wall insertion and peptidoglycan remodeling. Here, we show that ZapE, an ATPase that accumulates during late constriction, directly interacts with FtsZ and phospholipids in vitro. In the presence of adenosine triphosphate (ATP), ZapE induces bundling of GTP-induced FtsZ polymers; however, ZapE also binds FtsZ in the absence of GTP. The ZapE mutant protein ZapE(K84A), which is defective for ATP hydrolysis, also interacts with FtsZ and induces FtsZ filament bundling. In vivo, cultures of zapE deletion cells contain a low percentage of filamentous cells, suggesting that they have a modest division defect; however, they are able to grow when exposed to stress, such as high temperature and limited oxygen. When combined with the chromosomal deletion of minC, which encodes an FtsZ disassembly factor, ΔzapE ΔminC cells experience growth delays that slow proliferation at high temperature and prevent recovery. This synthetic slow growth phenotype after exposure to stress suggests that ZapE may function to ensure proliferation during and after stress, and this is exacerbated when cells are also deleted for minC. Expression of either ZapE or ZapE(K84A) complements the aberrant growth phenotypes in vivo suggesting that the division-associated role of ZapE does not require ZapE ATP hydrolysis. These results support that ZapE is a stress-regulated cell division protein that interacts directly with FtsZ and phospholipids, promoting growth and division after exposure to environmental stress.

scholarly journals Murein (Peptidoglycan) Binding Property of the Essential Cell Division Protein FtsN from Escherichia coli

2004 ◽  
Vol 186 (20) ◽  
pp. 6728-6737 ◽  
Author(s):  
Astrid Ursinus ◽  
Fusinita van den Ent ◽  
Sonja Brechtel ◽  
Miguel de Pedro ◽  
Joachim-Volker Höltje ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cell Division ◽  
Disulfide Bridge ◽  
Binding Property ◽  
Wild Type ◽  
E Coli ◽  
Specific Affinity ◽  
Cell Division Protein ◽  
Truncated Variants

ABSTRACT The binding of the essential cell division protein FtsN of Escherichia coli to the murein (peptidoglycan) sacculus was studied. Soluble truncated variants of FtsN, including the complete periplasmic part of the protein as well as a variant containing only the C-terminal 77 amino acids, did bind to purified murein sacculi isolated from wild-type cells. FtsN variants lacking this C-terminal region showed reduced or no binding to murein. Binding of FtsN was severely reduced when tested against sacculi isolated either from filamentous cells with blocked cell division or from chain-forming cells of a triple amidase mutant. Binding experiments with radioactively labeled murein digestion products revealed that the longer murein glycan strands (>25 disaccharide units) showed a specific affinity to FtsN, but neither muropeptides, peptides, nor short glycan fragments bound to FtsN. In vivo FtsN could be cross-linked to murein with the soluble disulfide bridge containing cross-linker DTSSP. Less FtsN, but similar amounts of OmpA, was cross-linked to murein of filamentous or of chain-forming cells compared to levels in wild-type cells. Expression of truncated FtsN variants in cells depleted in full-length FtsN revealed that the presence of the C-terminal murein-binding domain was not required for cell division under laboratory conditions. FtsN was present in 3,000 to 6,000 copies per cell in exponentially growing wild-type E. coli MC1061. We discuss the possibilities that the binding of FtsN to murein during cell division might either stabilize the septal region or might have a function unrelated to cell division.

scholarly journals Single-step purification of full-length human androgen receptor

2005 ◽  
Vol 3 (1) ◽  
pp. nrs.03001 ◽  
Author(s):  
Dalia Juzumiene ◽  
Ching-yi Chang ◽  
Daju Fan ◽  
Tanya Hartney ◽  
John D. Norris ◽  
...  
Keyword(s):  
Androgen Receptor ◽  
Affinity Chromatography ◽  
Spodoptera Frugiperda ◽  
Single Step ◽  
Full Length ◽  
Structural Studies ◽  
Site Specific ◽  
E Coli ◽  
Human Androgen Receptor

The full-length human androgen receptor with an N-terminal biotin acceptor peptide tag was overexpressed in Spodoptera frugiperda cells in the presence of 1 μM dihydrotestosterone. Site-specific biotinylation of BAP was achieved in vivo by co-expression of E. coli biotin holoenzyme synthetase. The androgen receptor was purified by single-step affinity chromatography using Streptavidin Mutein Matrix under native conditions. The resultant protein was active, stable, 95% homogeneous, and we obtained sufficient yield for use in functional and structural studies.

scholarly journals Bacterial actin MreB forms antiparallel double filaments

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Fusinita van den Ent ◽  
Thierry Izoré ◽  
Tanmay AM Bharat ◽  
Christopher M Johnson ◽  
Jan Löwe
Keyword(s):  
Crystal Structures ◽  
Conformational Changes ◽  
Cell Shape ◽  
Antimicrobial Agents ◽  
Nucleotide Hydrolysis ◽  
Site Specific ◽  
E Coli ◽  
Parallel Fashion

Filaments of all actin-like proteins known to date are assembled from pairs of protofilaments that are arranged in a parallel fashion, generating polarity. In this study, we show that the prokaryotic actin homologue MreB forms pairs of protofilaments that adopt an antiparallel arrangement in vitro and in vivo. We provide an atomic view of antiparallel protofilaments of Caulobacter MreB as apparent from crystal structures. We show that a protofilament doublet is essential for MreB's function in cell shape maintenance and demonstrate by in vivo site-specific cross-linking the antiparallel orientation of MreB protofilaments in E. coli. 3D cryo-EM shows that pairs of protofilaments of Caulobacter MreB tightly bind to membranes. Crystal structures of different nucleotide and polymerisation states of Caulobacter MreB reveal conserved conformational changes accompanying antiparallel filament formation. Finally, the antimicrobial agents A22/MP265 are shown to bind close to the bound nucleotide of MreB, presumably preventing nucleotide hydrolysis and destabilising double protofilaments.

scholarly journals Recapitulating the frataxin activation mechanism in an engineered bacterial cysteine desulfurase supports the architectural switch model

2020 ◽  
Author(s):  
Shachin Patra ◽  
Cheng-Wei Lin ◽  
Manas K. Ghosh ◽  
Steven M. Havens ◽  
Seth A. Cory ◽  
...  
Keyword(s):  
Life Forms ◽  
Activation Mechanism ◽  
Cysteine Desulfurase ◽  
Biochemical Processes ◽  
E Coli ◽  
A Subunit ◽  
Dimeric Form ◽  
Quaternary Structures ◽  
Low Activity

ABSTRACTIron-sulfur (Fe-S) clusters have a key role in many biochemical processes and are essential for most life forms. Despite recent mechanistic advances in understanding the Fe-S cluster biosynthetic pathway, critical questions remain unresolved. Although human NFS1 and E. coli IscS share ∼60% sequence identity, NFS1 exhibits low activity and requires activation by the Friedreich’s ataxia protein frataxin (FXN) for in vivo function. Surprisingly, structures of the human complex reveal three distinct quaternary structures with one form exhibiting the same subunit interactions as IscS. An architectural switch model has been proposed in which evolutionarily lost interactions between NFS1 subunits results in the formation of low-activity architectures; FXN binding compensates for these lost interactions and facilitates a subunit rearrangement to activate the complex. Here, we used a structure and evolution-guided approach to identify three conserved residues proposed to weaken interactions between NFS1 subunits and transplanted these amino acids into IscS. Compared to native IscS, the engineered variant had a 4000-fold weaker dimer interface and diminished activity that correlated with the absence of the second catalytic subunit. Remarkably, the addition of the FXN homolog to the engineered variant stimulated the decay of the Cys-quinonoid pyridoxal 5’-phosphate intermediate, shifted IscS from the monomeric to dimeric form, and increased the cysteine desulfurase activity, reproducing results from the human system and supporting the architectural switch model. Overall, these studies indicate a weakening of the homodimeric interface was a key development during the evolution of the eukaryotic system and provide new insights into the role of FXN.

scholarly journals Coregulated assembly of actin-like FtsA polymers with FtsZ during Z-ring formation and division in Escherichia coli

2021 ◽  
Author(s):  
Josiah J. Morrison ◽  
Joseph Conti ◽  
Jodi L. Camberg
Keyword(s):  
Escherichia Coli ◽  
Atp Hydrolysis ◽  
Direct Interaction ◽  
Ring Formation ◽  
Phospholipid Vesicle ◽  
E Coli ◽  
C Terminus ◽  
Z Ring

AbstractIn Escherichia coli, the actin homolog FtsA localizes the cell division machinery, beginning with the Z-ring, to the cytoplasmic membrane through direct interaction with FtsZ. FtsZ polymers are first to assemble at the Z-ring at midcell, where they direct constriction and septation. While FtsZ polymerization is critical for establishing a functional Z-ring that leads to constriction, the assembly state of FtsA and the role of FtsA ATP utilization during division in E. coli remain unclear. Here, we show that ATP hydrolysis, FtsZ interaction, and phospholipid vesicle remodeling by FtsA are impaired by a substitution mutation at the predicted active site for hydrolysis. This mutation, Glu 14 to Arg, also impairs Z-ring assembly and division in vivo. To further investigate the role of phospholipid engagement and ATP utilization in regulating FtsA function, we characterized a truncated E. coli FtsA variant, FtsA(ΔMTS), which lacks the region at the C-terminus important for engaging the membrane and is defective for ATP hydrolysis. We show that E. coli FtsA(ΔMTS) forms ATP-dependent actin-like filaments and assembly is antagonized by FtsZ. Polymerization of FtsZ with GTP, or a non-hydrolyzable analog, blocks inhibition of ATP-dependent FtsA assembly, and instead favors coassembly of stable FtsA/FtsZ polymers. In the cell, FtsA/FtsZ coassembly is favored at midcell, where FtsZ polymerizes, and inhibited at regions where FtsZ polymers are destabilized by regulators, such as MinC at the poles or SlmA at the nucleoid. We show that MinC prevents recruitment of FtsZ, via FtsA, to phospholipids, suggesting that local interactions of MinC with FtsZ block membrane tethering and uncouple the Z-ring from its major membrane contact. During Z-ring formation, the coassembly of FtsZ polymers with FtsA is coordinated and is a critical early step in division. This step also serves as a checkpoint by responding to the suite of FtsZ assembly regulators in the cell that modulate Z-ring position and dynamics prior to initiating cell wall synthesis.

scholarly journals A conserved cell division protein directly regulates FtsZ dynamics in filamentous and unicellular actinobacteria

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Félix Ramos-León ◽  
Matthew J Bush ◽  
Joseph W Sallmen ◽  
Govind Chandra ◽  
Jake Richardson ◽  
...  
Keyword(s):  
Cell Division ◽  
Bacterial Cell ◽  
Mycobacterium Smegmatis ◽  
Bacterial Cell Division ◽  
Z Ring ◽  
Cell Division Protein ◽  
Ring Architecture ◽  
Contractile Structure

Bacterial cell division is driven by the polymerization of the GTPase FtsZ into a contractile structure, the so-called Z-ring. This essential process involves proteins that modulate FtsZ dynamics and hence the overall Z-ring architecture. Actinobacteria like Streptomyces and Mycobacterium lack known key FtsZ-regulators. Here we report the identification of SepH, a conserved actinobacterial protein that directly regulates FtsZ dynamics. We show that SepH is crucially involved in cell division in Streptomyces venezuelae and that it binds FtsZ via a conserved helix-turn-helix motif, stimulating the assembly of FtsZ protofilaments. Comparative in vitro studies using the SepH homolog from Mycobacterium smegmatis further reveal that SepH can also bundle FtsZ protofilaments, indicating an additional Z-ring stabilizing function in vivo. We propose that SepH plays a crucial role at the onset of cytokinesis in actinobacteria by promoting the assembly of FtsZ filaments into division-competent Z-rings that can go on to mediate septum synthesis.

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