scholarly journals Cell wall synthesis and remodeling dynamics determine bacterial division site architecture and cell shape

2021 ◽  
Author(s):  
Paula P. Navarro ◽  
Andrea Vettiger ◽  
Virly Y Ananda ◽  
Paula Montero Llopis ◽  
Christoph Allolio ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Shape ◽  
Electron Tomography ◽  
Three Dimensional ◽  
E Coli ◽  
Gram Positive Bacteria ◽  
Division Site ◽  
Bacterial Division ◽  
Mutant Cells ◽  
Bacterial Domain

The bacterial division apparatus builds daughter cell poles by catalyzing the synthesis and remodeling of the septal peptidoglycan (sPG) cell wall. Understanding of this essential process has been limited by the lack of native three-dimensional visualization of developing septa. Here, we used state-of-the-art cryogenic electron tomography (cryo-ET) and fluorescence microscopy to understand the division site architecture and sPG biogenesis dynamics of the Gram-negative bacterium Escherichia coli. Our results with mutant cells altered in the regulation of sPG biogenesis revealed a striking and unexpected similarity between the architecture of E. coli septa with those from Gram-positive bacteria, suggesting a conserved morphogenic mechanism. Furthermore, we found that the cell elongation and division machineries are in competition and that their relative activities determine the shape of cell constrictions and the poles they form. Overall, our results highlight how the activity of the division system can be modulated to generate the diverse array of morphologies observed in the bacterial domain.

scholarly journals Cryo-Electron Tomography Reveals the Comparative Three-Dimensional Architecture of Prochlorococcus, a Globally Important Marine Cyanobacterium

2007 ◽  
Vol 189 (12) ◽  
pp. 4485-4493 ◽  
Author(s):  
Claire S. Ting ◽  
Chyongere Hsieh ◽  
Sesh Sundararaman ◽  
Carmen Mannella ◽  
Michael Marko
Keyword(s):  
Cell Wall ◽  
Electron Tomography ◽  
Three Dimensional ◽  
Membrane System ◽  
Niche Differentiation ◽  
Dimensional Structure ◽  
Comparative Genomic ◽  
Photosynthetic Membrane ◽  
Peptidoglycan Biosynthesis ◽  
Cryo Electron Tomography

ABSTRACT In an age of comparative microbial genomics, knowledge of the near-native architecture of microorganisms is essential for achieving an integrative understanding of physiology and function. We characterized and compared the three-dimensional architecture of the ecologically important cyanobacterium Prochlorococcus in a near-native state using cryo-electron tomography and found that closely related strains have diverged substantially in cellular organization and structure. By visualizing native, hydrated structures within cells, we discovered that the MED4 strain, which possesses one of the smallest genomes (1.66 Mbp) of any known photosynthetic organism, has evolved a comparatively streamlined cellular architecture. This strain possesses a smaller cell volume, an attenuated cell wall, and less extensive intracytoplasmic (photosynthetic) membrane system compared to the more deeply branched MIT9313 strain. Comparative genomic analyses indicate that differences have evolved in key structural genes, including those encoding enzymes involved in cell wall peptidoglycan biosynthesis. Although both strains possess carboxysomes that are polygonal and cluster in the central cytoplasm, the carboxysomes of MED4 are smaller. A streamlined cellular structure could be advantageous to microorganisms thriving in the low-nutrient conditions characteristic of large regions of the open ocean and thus have consequences for ecological niche differentiation. Through cryo-electron tomography we visualized, for the first time, the three-dimensional structure of the extensive network of photosynthetic lamellae within Prochlorococcus and the potential pathways for intracellular and intermembrane movement of molecules. Comparative information on the near-native structure of microorganisms is an important and necessary component of exploring microbial diversity and understanding its consequences for function and ecology.

METHODS FOR INDICATION OF NONCULTURATED VIABLE MICROORGANISMS WHEN CONTROL OF CRITICAL POINTS OF LIVESTOCK, POULTRY AND FOOD PRODUCTION TECHNOLOGY

2021 ◽  
Vol 1 (4) ◽  
pp. 441-447
Author(s):  
Ekaterina M. Lenchenko ◽  
◽  
Damir I. Udavliev ◽  
Inna B. Pavlova ◽  
◽  
...  
Keyword(s):  
Cell Wall ◽  
Luminescence Spectrum ◽  
Three Dimensional ◽  
Yeast Cells ◽  
Dimensional Structure ◽  
Heterogeneous Structure ◽  
Bacterial Cells ◽  
Microscopic Fungi ◽  
Gram Positive Bacteria ◽  
Red Luminescence

The results of morphometric and densitometric parameters biofilms are presented, effective methods of detecting uncultivated viable microorganisms isolated from a representative sample of objects of veterinary and sanitary supervision are tested and selected. Optical, luminescent and scanning electron microscopy revealed the formation of a three-dimensional structure biofilms in the form a dense network consisting of gram-negative and gram-positive bacteria, yeast cells, hyphal and pseudohyphalic forms, surrounded by an intercellular polymer matrix. The presence hyphae of microscopic fungi causes an increase in the number of cells adhered to the substrate, microcolonies were formed from bacteria and yeast cells of microscopic fungi. The pathogenesis of the syndrome of overgrowth of microorganisms is provided by the presence of various dissociative variants, the dispersion of uncultivated bacterial cells, which gain advantages in the hyperagregation of the architectonics of heterogeneous biofilms. Multilayer membranes, vesicles, cells with a defective cell wall, spheroplasts, protoplasts, L-shapes, needle-like and giant structures, and revertant cells were identified. The dynamics of changes in the viable structures microorganisms was characterized by alternating periods of decrease and increase in the intensity of biofilm formation. When detecting the viability of microorganisms in the composition biofilms, viable and non-viable cells were differentiated – a green luminescence spectrum and a red luminescence spectrum, respectively. The dissociation of the population caused an increase in the concentration of R-dissociant cells with a higher growth rate, cell lysis was detected after 48–72 h of cultivation, a change in the ratio phenotypic forms was observed – the M-dissociant was predominant. The study of the heterogeneous structure of the population, without disturbing the natural architectonics of biofilms, revealed direct correlations (r = 0,89) between morphometric (≥90 % of the field of view) and densitometric parameters (OD). The efficiency of a nutrient medium containing pancreatic hydrolyzate, mannitol, L-asparagine and glycerol was established for the repair of the cell wall, the reversal of L-forms of microorganisms.

scholarly journals The Tol-Pal system is required for peptidoglycan-cleaving enzymes to complete bacterial cell division

2020 ◽  
Vol 117 (12) ◽  
pp. 6777-6783 ◽  
Author(s):  
Anastasiya A. Yakhnina ◽  
Thomas G. Bernhardt
Keyword(s):  
Cell Separation ◽  
Glycosyl Hydrolase ◽  
Gram Negative Bacteria ◽  
Bacterial Cell Division ◽  
General Role ◽  
E Coli ◽  
Division Site ◽  
Genetic Suppressors ◽  
Bacteria Inactivation ◽  
Mutant Cells

Tol-Pal is a multiprotein system present in the envelope of Gram-negative bacteria. Inactivation of this widely conserved machinery compromises the outer membrane (OM) layer of these organisms, resulting in hypersensitivity to many antibiotics. Mutants in thetol-pallocus fail to complete division and form cell chains. This phenotype along with the localization of Tol-Pal components to the cytokinetic ring inEscherichia colihas led to the proposal that the primary function of the system is to promote OM constriction during division. Accordingly, a poorly constricted OM is believed to link the cell chains formed upon Tol-Pal inactivation. However, we show here that cell chains ofE. coli tol-palmutants are connected by an incompletely processed peptidoglycan (PG) layer. Genetic suppressors of this defect were isolated and found to overproduce OM lipoproteins capable of cleaving the glycan strands of PG. Among the factors promoting cell separation in mutant cells was a protein of previously unknown function (YddW), which we have identified as a divisome-localized glycosyl hydrolase that cleaves peptide-free PG glycans. Overall, our results indicate that the cell chaining defect of Tol-Pal mutants cannot simply be interpreted as a defect in OM constriction. Rather, the complex also appears to be required for the activity of several OM-localized enzymes with cell wall remodeling activity. Thus, the Tol-Pal system may play a more general role in coordinating OM invagination with PG remodeling at the division site than previously appreciated.

scholarly journals MurF Inhibitors with Antibacterial Activity: Effect on Muropeptide Levels

2009 ◽  
Vol 53 (8) ◽  
pp. 3240-3247 ◽  
Author(s):  
Ellen Z. Baum ◽  
Steven M. Crespo-Carbone ◽  
Barbara D. Foleno ◽  
Lee D. Simon ◽  
Jerome Guillemont ◽  
...  
Keyword(s):  
Cell Wall ◽  
Pharmacophore Model ◽  
Polymyxin B ◽  
Bacterial Survival ◽  
Wild Type ◽  
E Coli ◽  
Gram Positive Bacteria ◽  
Activity Effect ◽  
Modest Activity

ABSTRACT MurF catalyzes the last cytoplasmic step of bacterial cell wall synthesis and is essential for bacterial survival. Our previous studies used a pharmacophore model of a MurF inhibitor to identify additional inhibitors with improved properties. We now present the characterization of two such inhibitors, the diarylquinolines DQ1 and DQ2. DQ1 inhibited Escherichia coli MurF (50% inhibitory concentration, 24 μM) and had modest activity (MICs, 8 to 16 μg/ml) against lipopolysaccharide (LPS)-defective E. coli and wild-type E. coli rendered permeable with polymyxin B nonapeptide. DQ2 additionally displayed activity against gram-positive bacteria (MICs, 8 to 16 μg/ml), including methicillin (meticillin)-susceptible and -resistant Staphylococcus aureus isolates and vancomycin-susceptible and -resistant Enterococcus faecalis and Enterococcus faecium isolates. Treatment of LPS-defective E. coli cells with ≥2× MIC of DQ1 resulted in a 75-fold-greater accumulation of the MurF substrate compared to the control, a 70% decline in the amount of the MurF product, and eventual cell lysis, consistent with the inhibition of MurF within bacteria. DQ2 treatment of S. aureus resulted in similar effects on the MurF substrate and product quantities. At lower levels of DQ1 (≤1× MIC), the level of accumulation of the substrate was less pronounced (15-fold greater compared to the amount for the control). However, a 50% increase in the amount of the MurF product compared to the control was reproducibly observed, consistent with the possible upregulation of muropeptide biosynthesis upon partial inhibition of this pathway. The overexpression of cloned MurF appeared to partly alleviate the DQ1-mediated inhibition of muropeptide synthesis. The identification of MurF inhibitors such as DQ1 and DQ2 that disrupt cell wall biosynthesis suggests that MurF remains a viable target for an antibacterial agent.

scholarly journals RodZ modulates geometric localization of the bacterial actin MreB to regulate cell shape

2017 ◽  
Author(s):  
Alexandre Colavin ◽  
Handuo Shi ◽  
Kerwyn Casey Huang
Keyword(s):  
Cell Wall ◽  
Cell Shape ◽  
Spatial Organization ◽  
Dependent Manner ◽  
Cell Width ◽  
E Coli ◽  
Wall Growth ◽  
The Rich ◽  
Dynamics Simulations ◽  
Geometric Localization

AbstractIn the rod-shaped bacteriumEscherichia coli, the actin-like protein MreB localizes in a curvature-dependent manner and spatially coordinates cell-wall insertion to maintain cell shape across changing environments, although the molecular mechanism by which cell width is regulated remains unknown. Here, we demonstrate that the bitopic membrane protein RodZ regulates the biophysical properties of MreB and alters the spatial organization ofE. colicell-wall growth. The relative expression levels of MreB and RodZ changed in a manner commensurate with variations in growth rate and cell width. We carried out single-cell analyses to determine that RodZ systematically alters the curvature-based localization of MreB and cell width in a manner dependent on the concentration of RodZ. Finally, we identified MreB mutants that we predict using molecular dynamics simulations to alter the bending properties of MreB filaments at the molecular scale similar to RodZ binding, and showed that these mutants rescued rod-like shape in the absence of RodZ alone or in combination with wild-type MreB. Together, our results show thatE. colicontrols its shape and dimensions by differentially regulating RodZ and MreB to alter the patterning of cell-wall insertion, highlighting the rich regulatory landscape of cytoskeletal molecular biophysics.

scholarly journals RodZ promotes MreB polymer formation and curvature localization to determine the cylindrical uniformity of E. coli shape

2017 ◽  
Author(s):  
Randy M. Morgenstein ◽  
Benjamin P. Bratton ◽  
Joshua W. Shaevitz ◽  
Zemer Gitai
Keyword(s):  
Cell Wall ◽  
Single Cell ◽  
Cell Body ◽  
Cell Shape ◽  
E Coli ◽  
Total Length ◽  
Polymer Formation ◽  
Mutant Strains ◽  
Geometric Cues ◽  
Cell Changes

AbstractCell shape in bacteria is determined by the cell wall, which is synthesized by a variety of proteins whose actions are coordinated by the actin-like MreB protein. MreB uses local geometric cues of envelope curvature to avoid the cell poles and localize to specific regions of the cell body. However, it remains unclear whether MreB’s curvature preference is regulated by additional factors, and which features of MreB are essential for specific aspects of rod shape growth, such as cylindrical uniformity. Here we show that in addition to its previously-described role in mediating MreB motion, RodZ also modulates MreB polymer number and curvature preference. MreB polymer number and curvature localization can be regulated independently. Quantitative 3D measurements and a series of mutant strains show that among various properties of MreB, polymer number, total length of MreB polymers, and MreB curvature preference are the key determinants of cylindrical uniformity, a measure of the variability in radius within a single cell. Changes in the values of these parameters are highly predictive of the resulting changes in cell shape (r2=0.93). Our data suggest a model for rod shape in which RodZ promotes the assembly of multiple long MreB polymers that ensure the growth of a uniform cylinder.

scholarly journals Bacterial envelope damage inflicted by bioinspired nanospikes grown in a hydrogel

2020 ◽  
Author(s):  
Sandra L. Arias ◽  
Joshua Devorkin ◽  
Jessica C. Spear ◽  
Ana Civantos ◽  
Jean Paul Allain
Keyword(s):  
Mechanical Properties ◽  
Antimicrobial Activity ◽  
Cell Wall ◽  
Mammalian Cells ◽  
Cell Shape ◽  
Rational Design ◽  
Bacterial Cells ◽  
Nanoscale Structures ◽  
Gram Positive Bacteria ◽  
Tissue Restoration

AbstractDevice-associated infections are one of the deadliest complications accompanying the use of biomaterials, and despite recent advances in the development of anti-biofouling strategies, biomaterials that exhibit both functional tissue restoration and antimicrobial activity have been challenging to achieve. Here, we report the fabrication of bio-inspired bactericidal nanospikes in bacterial cellulose and investigate the mechanism underlying this phenomenon. We demonstrate these structures affects preferentially stiff membranes like those in Gram-positive bacteria, but exhibit cytocompatibility towards mammalian cells, a requisite for tissue restoration. We also reveal the bactericidal activity of the nanospikes is due to a pressure-induced mechanism, which depends on the cell’s adherence time, nanospike’s geometry and spacing, cell shape, and mechanical properties of the cell wall. Our findings provide a better understanding of the mechanobiology of bacterial cells at the interface with nanoscale structures, which is fundamental for the rational design bactericidal topographies.

scholarly journals An inducible AraC that responds to blue light instead of arabinose

2020 ◽  
Author(s):  
Edoardo Romano ◽  
Armin Baumschlager ◽  
Emir Bora Akmeriç ◽  
Navaneethan Palanisamy ◽  
Moustafa Houmani ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Blue Light ◽  
Cell Shape ◽  
Control Cell ◽  
Dna Binding Protein ◽  
Dimerization Domain ◽  
E Coli ◽  
Division Site ◽  
The Many

In Escherichia coli, the operon responsible for the catabolism of L-arabinose is regulated by the dimeric DNA-binding protein AraC. In the absence of L-arabinose, AraC binds to the distal I1 and O2 half-sites, leading to repression of the downstream PBAD promoter. In the presence of the sugar, the dimer changes conformation and binds to the adjacent I1 and I2 half-sites, resulting in the activation of PBAD. Here we engineer blue light-inducible AraC dimers in Escherichia coli (BLADE) by swapping the dimerization domain of AraC with blue light-inducible dimerization domains. Using BLADE to overexpress proteins important for cell shape and division site selection, we reversibly control cell morphology with light. We demonstrate the exquisite light responsiveness of BLADE by employing it to create bacteriographs with an unprecedented quality. We then employ it to perform a medium-throughput characterization of 39 E. coli genes with poorly defined or completely unknown function. Finally, we expand the initial library and create a whole family of BLADE transcription factors (TFs), which we characterize using a novel 96-well light induction setup. Since the PBAD promoter is commonly used by microbiologists, we envisage that the BLADE TFs will bring the many advantages of optogenetic gene expression to the field of microbiology.

scholarly journals Three-Dimensional Electron Microscopic Imaging of Membrane Invaginations in Escherichia coli Overproducing the Chemotaxis Receptor Tsr

2004 ◽  
Vol 186 (15) ◽  
pp. 5052-5061 ◽  
Author(s):  
Jonathan Lefman ◽  
Peijun Zhang ◽  
Teruhisa Hirai ◽  
Robert M. Weis ◽  
Jemma Juliani ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Electron Tomography ◽  
Three Dimensional ◽  
Bacterial Chemotaxis ◽  
Molecular Architecture ◽  
Electron Microscopic ◽  
E Coli ◽  
Macromolecular Assemblies ◽  
Membrane Networks ◽  
Receptor Clusters

ABSTRACT Electron tomography is a powerful method for determining the three-dimensional structures of large macromolecular assemblies, such as cells, organelles, and multiprotein complexes, when crystallographic averaging methods are not applicable. Here we used electron tomographic imaging to determine the molecular architecture of Escherichia coli cells engineered to overproduce the bacterial chemotaxis receptor Tsr. Tomograms constructed from fixed, cryosectioned cells revealed that overproduction of Tsr led to formation of an extended internal membrane network composed of stacks and extended tubular structures. We present an interpretation of the tomogram in terms of the packing arrangement of Tsr using constraints derived from previous X-ray and electron-crystallographic studies of receptor clusters. Our results imply that the interaction between the cytoplasmic ends of Tsr is likely to stabilize the presence of the membrane networks in cells overproducing Tsr. We propose that membrane invaginations that are potentially capable of supporting axial interactions between receptor clusters in apposing membranes could also be present in wild-type E. coli and that such receptor aggregates could play an important role in signal transduction during bacterial chemotaxis.

scholarly journals The Escherichia coli Homologue of Yeast Rer2, a Key Enzyme of Dolichol Synthesis, Is Essential for Carrier Lipid Formation in Bacterial Cell Wall Synthesis

1999 ◽  
Vol 181 (9) ◽  
pp. 2733-2738 ◽  
Author(s):  
Jun-ichi Kato ◽  
Shingo Fujisaki ◽  
Ken-ichi Nakajima ◽  
Yukinobu Nishimura ◽  
Miyuki Sato ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Micrococcus Luteus ◽  
Cellular Level ◽  
Temperature Sensitive ◽  
E Coli ◽  
Lipid Formation ◽  
Endoplasmic Reticulum Protein ◽  
Key Enzyme ◽  
Mutant Cells

ABSTRACT We found in the Escherichia coli genome sequence a homologue of RER2, a Saccharomyces cerevisiaegene required for proper localization of an endoplasmic reticulum protein, and designated it rth (RER2homologue). The disruption of this gene was lethal for E. coli. To reveal its biological function, we isolated temperature-sensitive mutants of the rth gene. The mutant cells became swollen and burst at the nonpermissive temperature, indicating that their cell wall integrity was defective. Further analysis showed that the mutant cells were deficient in the activity ofcis-prenyltransferase, namely, undecaprenyl diphosphate synthase, a key enzyme of the carrier lipid formation of peptidoglycan synthesis. The cellular level of undecaprenyl phosphate was in fact markedly decreased in the mutants. These results are consistent with the fact that the Rer2 homologue of Micrococcus luteusshows undecaprenyl diphosphate synthase activity (N. Shimizu, T. Koyama, and K. Ogura, J. Biol. Chem. 273:19476–19481, 1998) and demonstrate that E. coli Rth is indeed responsible for the maintenance of cell wall rigidity. Our work on the yeastrer2 mutants shows that they are defective in the activity of cis-prenyltransferase, namely, dehydrodolichyl diphosphate synthase, a key enzyme of dolichol synthesis. Taking these data together, we conclude that the RER2 gene family encodes cis-prenyltransferase, which plays an essential role in cell wall biosynthesis in bacteria and in dolichol synthesis in eukaryotic cells and has been well conserved during evolution.

Sign in / Sign up

Export Citation Format

Share Document