scholarly journals Recent advances in understanding how rod-like bacteria stably maintain their cell shapes

F1000Research ◽  
2018 ◽  
Vol 7 ◽  
pp. 241 ◽  
Author(s):  
Sven van Teeffelen ◽  
Lars D. Renner
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Cell Shape ◽  
Theoretical Work ◽  
Model Organisms ◽  
Mechanical Forces ◽  
Recent Developments ◽  
Cell Shapes ◽  
Shape And Size ◽  
Cell Wall Expansion

Cell shape and cell volume are important for many bacterial functions. In recent years, we have seen a range of experimental and theoretical work that led to a better understanding of the determinants of cell shape and size. The roles of different molecular machineries for cell-wall expansion have been detailed and partially redefined, mechanical forces have been shown to influence cell shape, and new connections between metabolism and cell shape have been proposed. Yet the fundamental determinants of the different cellular dimensions remain to be identified. Here, we highlight some of the recent developments and focus on the determinants of rod-like cell shape and size in the well-studied model organismsEscherichia coliandBacillus subtilis.

scholarly journals Antigen 84, an Effector of Pleiomorphism in Mycobacterium smegmatis

2007 ◽  
Vol 189 (21) ◽  
pp. 7896-7910 ◽  
Author(s):  
Liem Nguyen ◽  
Nicole Scherr ◽  
John Gatfield ◽  
Anne Walburger ◽  
Jean Pieters ◽  
...  
Keyword(s):  
Cell Wall ◽  
Mycobacterium Smegmatis ◽  
Cell Shape ◽  
Gene Disruption ◽  
Gene Encoding ◽  
Peptidoglycan Biosynthesis ◽  
Asymmetrically Distributed ◽  
Cell Wall Expansion

ABSTRACT While in most rod-shaped bacteria, morphology is based on MreB-like proteins that form an actin-like cytoskeletal scaffold for cell wall biosynthesis, the factors that determine the more flexible rod-like shape in actinobacteria such as Mycobacterium species are unknown. Here we show that a Mycobacterium smegmatis protein homologous to eubacterial DivIVA-like proteins, including M. tuberculosis antigen 84 (Ag84), localized symmetrically to centers of peptidoglycan biosynthesis at the poles and septa. Controlled gene disruption experiments indicated that the gene encoding Ag84, wag31, was essential; when overexpressed, cells became longer and wider, with Ag84 asymmetrically distributed at one pole. Many became grossly enlarged, bowling-pin-shaped cells having up to 80-fold-increased volume. In these cells, Ag84 accumulated predominantly at a bulbous pole that was apparently generated by uncontrolled cell wall expansion. In some cells, Ag84 was associated with exceptional sites of cell wall expansion (buds) that evolved into branches. M. bovis BCG Ag84 was able to form oligomers in vitro, perhaps reflecting its superstructure in vivo. These data suggested a role for Ag84 in cell division and modulating cell shape in pleiomorphic actinobacteria.

scholarly journals Mechanical properties of the stigmatic cell wall mediate pollen tube path in Arabidopsis

2018 ◽  
Author(s):  
Lucie Riglet ◽  
Frédérique Rozier ◽  
Chie Kodera ◽  
Isabelle Fobis-Loisy ◽  
Thierry Gaude
Keyword(s):  
Cell Wall ◽  
Pollen Tube ◽  
Cell Shape ◽  
Cell Imaging ◽  
Pollen Tubes ◽  
Mechanical Anisotropy ◽  
Cellulose Microfibrils ◽  
Mechanical Forces ◽  
Cortical Microtubules ◽  
Isotropic Reorientation

ABSTRACTSuccessful fertilization in angiosperms depends on the proper trajectory of pollen tubes through the pistil tissues to reach the ovules. Pollen tubes first grow within the cell wall of the papilla cells, applying pressure to the cell. Mechanical forces are known to play a major role in plant cell shape by controlling the orientation of cortical microtubules (CMTs), which in turn mediate deposition of cellulose microfibrils (CMFs). Here, by combining cell imaging and genetic approaches, we show that isotropic reorientation of CMTs and CMFs in aged and katanin1-5 (ktn1-5) papilla cells is accompanied by a tendency of pollen tubes to coil around the papillae. Furthermore, we uncover that aged and ktn1-5 papilla cells have a softer cell wall and provide less resistance to pollen tube growth. Our results reveal an unexpected role for KTN1 in pollen tube guidance by ensuring mechanical anisotropy of the papilla cell wall.

scholarly journals Bacterial Cell Wall Synthesis: New Insights from Localization Studies

2005 ◽  
Vol 69 (4) ◽  
pp. 585-607 ◽  
Author(s):  
Dirk-Jan Scheffers ◽  
Mariana G. Pinho
Keyword(s):  
Cell Wall ◽  
Bacterial Cell ◽  
Cell Shape ◽  
Fluorescent Protein ◽  
Model Organisms ◽  
Live Cells ◽  
Cell Wall Synthesis ◽  
A Cell ◽  
Green Fluorescent ◽  
Bacterial Cell Shape

SUMMARY In order to maintain shape and withstand intracellular pressure, most bacteria are surrounded by a cell wall that consists mainly of the cross-linked polymer peptidoglycan (PG). The importance of PG for the maintenance of bacterial cell shape is underscored by the fact that, for various bacteria, several mutations affecting PG synthesis are associated with cell shape defects. In recent years, the application of fluorescence microscopy to the field of PG synthesis has led to an enormous increase in data on the relationship between cell wall synthesis and bacterial cell shape. First, a novel staining method enabled the visualization of PG precursor incorporation in live cells. Second, penicillin-binding proteins (PBPs), which mediate the final stages of PG synthesis, have been localized in various model organisms by means of immunofluorescence microscopy or green fluorescent protein fusions. In this review, we integrate the knowledge on the last stages of PG synthesis obtained in previous studies with the new data available on localization of PG synthesis and PBPs, in both rod-shaped and coccoid cells. We discuss a model in which, at least for a subset of PBPs, the presence of substrate is a major factor in determining PBP localization.

scholarly journals Evolution of Penicillin-Binding Protein 2 Concentration and Cell Shape during a Long-Term Experiment with Escherichia coli

2008 ◽  
Vol 191 (3) ◽  
pp. 909-921 ◽  
Author(s):  
Nadège Philippe ◽  
Ludovic Pelosi ◽  
Richard E. Lenski ◽  
Dominique Schneider
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Cell Shape ◽  
Dynamic Structure ◽  
Growth Cycle ◽  
Ecological Specialization ◽  
Term Experiment ◽  
Trade Offs ◽  
Long Term Experiment

ABSTRACT Peptidoglycan is the major component of the bacterial cell wall and is involved in osmotic protection and in determining cell shape. Cell shape potentially influences many processes, including nutrient uptake as well as cell survival and growth. Peptidoglycan is a dynamic structure that changes during the growth cycle. Penicillin-binding proteins (PBPs) catalyze the final stages of peptidoglycan synthesis. Although PBPs are biochemically and physiologically well characterized, their broader effects, especially their effects on organismal fitness, are not well understood. In a long-term experiment, 12 populations of Escherichia coli having a common ancestor were allowed to evolve for more than 40,000 generations in a defined environment. We previously identified mutations in the pbpA operon in one-half of these populations; this operon encodes PBP2 and RodA proteins that are involved in cell wall elongation. In this study, we characterized the effects of two of these mutations on competitive fitness and other phenotypes. By constructing and performing competition experiments with strains that are isogenic except for the pbpA alleles, we showed that both mutations that evolved were beneficial in the environment used for the long-term experiment and that these mutations caused parallel phenotypic changes. In particular, they reduced the cellular concentration of PBP2, thereby generating spherical cells with an increased volume. In contrast to their fitness-enhancing effect in the environment where they evolved, both mutations decreased cellular resistance to osmotic stress. Moreover, one mutation reduced fitness during prolonged stationary phase. Therefore, alteration of the PBP2 concentration contributed to physiological trade-offs and ecological specialization during experimental evolution.

scholarly journals A study of epidermal leaf anatomy of 18 Euphorbia taxa from Kerman Province, Iran

Biologija ◽  
2017 ◽  
Vol 63 (2) ◽  
Author(s):  
Seyed Mehdi Talebi ◽  
Mitra Noori ◽  
Habibeh Afzali Naniz
Keyword(s):  
Cell Wall ◽  
Epidermal Cell ◽  
Leaf Anatomy ◽  
Cell Shape ◽  
Leaf Epidermis ◽  
Abaxial Surface ◽  
Leaf Epidermal Cell ◽  
Leaf Surfaces ◽  
Cell Shapes ◽  
Different Parts

Euphorbia is the largest genus of Euphorbiaceae widely distributed all over the world. The genus members grow naturally in different parts of Iran and nearly 96 species of Euphorbia have been listed in the country. Investigations show that the traits of foliar epidermis have taxonomic values. That is why the features of epidermal leaf anatomy of 18 Euphorbia taxa were studied in the present study. Plant samples were collected from Kerman Province, Iran, and identified using available references. Semi-permanent slides were prepared of adaxial and abaxial leaf epidermis. Then the slides were studied using light microscopy and some epidermal leaf anatomy characteristics stomata types, trichomes, the shape and type of epidermal cell, and their walls were examined. Photomicrographs were taken from each sample. Results showed that stomata type were stable among the species. Not only leaf epidermal cell shapes differed between the taxa, but also in some species they varied between the abaxial and adaxial surfaces. These conditions hold true for cell wall patterns. Some of the studied taxa had simple and uniseriate trichomes on the epidermal surfaces, in most of them trichomes were present on both leaf surfaces, while in one species trichomes were seen on the abaxial surface. Our findings confirmed that some of the anatomical traits, such as the absence or presence of trichomes, epidermal cell shape, and anticlinal cell wall patterns had taxonomic value and are useful in the identification of taxa.

scholarly journals Behavior of the Meat-Borne Bacterium Lactobacillus sakei during Its Transit through the Gastrointestinal Tracts of Axenic and Conventional Mice

2009 ◽  
Vol 75 (13) ◽  
pp. 4498-4505 ◽  
Author(s):  
Fabrizio Chiaramonte ◽  
Sébastien Blugeon ◽  
Stéphane Chaillou ◽  
Philippe Langella ◽  
Monique Zagorec
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Lactobacillus Sakei ◽  
Human Feces ◽  
Positive Bacterium ◽  
Food Grade ◽  
Food Borne ◽  
Genetic Features ◽  
Cell Shapes ◽  
First Time

ABSTRACT A Lactobacillus sakei strain named FLEC01 was isolated from human feces and characterized genotypically. Comparison of the genetic features of this strain with those of both the meat-borne L. sakei strain 23K and another human isolate, LTH5590, showed that they belong to different but closely related clusters. The three L. sakei strains did not persist and only transited through the gastrointestinal tracts (GITs) of conventional C3H/HeN mice. In contrast, they all colonized the GITs of axenic mice and rapidly reached a population of 109 CFU/g of feces, which remained stable until day 51. Five days after mice were fed, a first subpopulation, characterized by small colonies, appeared and reached 50% of the total L. sakei population in mice. Fifteen to 21 days after feeding, a second subpopulation, characterized by rough colonies, appeared. It coexisted with the two other populations until day 51, and its cell shapes were also affected, suggesting a dysfunction of the cell division or cell wall. No clear difference between the behaviors of the meat-borne strain and the two human isolates in both conventional and axenic mice was observed, suggesting that L. sakei is a food-borne bacterium rather than a commensal one and that its presence in human feces originates from diet. Previous observations of Escherichia coli strains suggest that the mouse GIT environment could induce mutations to increase their survival and colonization capacities. Here, we observed similar mutations concerning a food-grade gram-positive bacterium for the first time.

scholarly journals Characterization of Conserved and Novel Septal Factors inMycobacterium smegmatis

2018 ◽  
Vol 200 (6) ◽  
Author(s):  
Katherine J. Wu ◽  
Jenna Zhang ◽  
Catherine Baranowski ◽  
Vivian Leung ◽  
E. Hesper Rego ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Model Organisms ◽  
Wall Structure ◽  
Cross Wall ◽  
Content Type ◽  
A Cell ◽  
Mediate Cell ◽  
Mycobacterial Cell Wall ◽  
Regulatory Functions

ABSTRACTSeptation in bacteria requires coordinated regulation of cell wall biosynthesis and hydrolysis enzymes so that new septal cross-wall can be appropriately constructed without compromising the integrity of the existing cell wall. Bacteria with different modes of growth and different types of cell wall require different regulators to mediate cell growth and division processes. Mycobacteria have both a cell wall structure and a mode of growth that are distinct from well-studied model organisms and use several different regulatory mechanisms. Here, usingMycobacterium smegmatis, we identify and characterize homologs of the conserved cell division regulators FtsL and FtsB, and show that they appear to function similarly to their homologs inEscherichia coli. We identify a number of previously undescribed septally localized factors which could be involved in cell wall regulation. One of these, SepIVA, has a DivIVA domain, is required for mycobacterial septation, and is localized to the septum and the intracellular membrane domain. We propose that SepIVA is a regulator of cell wall precursor enzymes that contribute to construction of the septal cross-wall, similar to the putative elongation function of the other mycobacterial DivIVA homolog, Wag31.IMPORTANCEThe enzymes that build bacterial cell walls are essential for cell survival but can cause cell lysis if misregulated; thus, their regulators are also essential. The number and nature of these regulators is likely to vary in bacteria that grow in different ways. The mycobacteria are a genus that have a cell wall whose composition and construction vary greatly from those of well-studied model organisms. In this work, we identify and characterize some of the proteins that regulate the mycobacterial cell wall. We find that some of these regulators appear to be functionally conserved with their structural homologs in evolutionarily distant species such asEscherichia coli, but other proteins have critical regulatory functions that may be unique to the actinomycetes.

Sites of Adsorption of the Bacteriophages T3 and T5 on the Wall of Escherichia Coli B.

1967 ◽  
Vol 25 ◽  
pp. 96-97
Author(s):  
Manfred E. Bayer
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Electron Microscope ◽  
Uranyl Acetate ◽  
E Coli ◽  
Receptor Sites ◽  
Rigid Cell Wall ◽  
Host Cell Surface ◽  
Bacterial Viruses ◽  
Escherichia Coli B

Bacterial viruses adsorb specifically to receptors on the host cell surface. Although the chemical composition of some of the cell wall receptors for bacteriophages of the T-series has been described and the number of receptor sites has been estimated to be 150 to 300 per E. coli cell, the localization of the sites on the bacterial wall has been unknown.When logarithmically growing cells of E. coli are transferred into a medium containing 20% sucrose, the cells plasmolize: the protoplast shrinks and becomes separated from the somewhat rigid cell wall. When these cells are fixed in 8% Formaldehyde, post-fixed in OsO4/uranyl acetate, embedded in Vestopal W, then cut in an ultramicrotome and observed with the electron microscope, the separation of protoplast and wall becomes clearly visible, (Fig. 1, 2). At a number of locations however, the protoplasmic membrane adheres to the wall even under the considerable pull of the shrinking protoplast. Thus numerous connecting bridges are maintained between protoplast and cell wall. Estimations of the total number of such wall/membrane associations yield a number of about 300 per cell.

Recent Developments in the Downstream Processing of Phycobiliproteins from Algae: A Review

2021 ◽  
Vol 06 ◽  
Author(s):  
Ayekpam Chandralekha Devi ◽  
G. K. Hamsavi ◽  
Simran Sahota ◽  
Rochak Mittal ◽  
Hrishikesh A. Tavanandi ◽  
...  
Keyword(s):  
Cell Wall ◽  
Large Scale ◽  
Downstream Processing ◽  
Review Article ◽  
Current Status ◽  
Wall Structure ◽  
Scale Production ◽  
Cell Wall Disruption ◽  
Recent Developments ◽  
Macro Algae

Abstract: Algae (both micro and macro) have gained huge attention in the recent past for their high commercial value products. They are the source of various biomolecules of commercial applications ranging from nutraceuticals to fuels. Phycobiliproteins are one such high value low volume compounds which are mainly obtained from micro and macro algae. In order to tap the bioresource, a significant amount of work has been carried out for large scale production of algal biomass. However, work on downstream processing aspects of phycobiliproteins (PBPs) from algae is scarce, especially in case of macroalgae. There are several difficulties in cell wall disruption of both micro and macro algae because of their cell wall structure and compositions. At the same time, there are several challenges in the purification of phycobiliproteins. The current review article focuses on the recent developments in downstream processing of phycobiliproteins (mainly phycocyanins and phycoerythrins) from micro and macroalgae. The current status, the recent advancements and potential technologies (that are under development) are summarised in this review article besides providing future directions for the present research area.

scholarly journals Probing bacterial cell wall growth by tracing wall-anchored protein complexes

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yi-Jen Sun ◽  
Fan Bai ◽  
An-Chi Luo ◽  
Xiang-Yu Zhuang ◽  
Tsai-Shun Lin ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Shape ◽  
Bernoulli Shift ◽  
Protein Complexes ◽  
Axial Direction ◽  
Cell Wall Growth ◽  
Flagellar Motors ◽  
Shift Map ◽  
Dynamic Assembly ◽  
Wall Growth

AbstractThe dynamic assembly of the cell wall is key to the maintenance of cell shape during bacterial growth. Here, we present a method for the analysis of Escherichia coli cell wall growth at high spatial and temporal resolution, which is achieved by tracing the movement of fluorescently labeled cell wall-anchored flagellar motors. Using this method, we clearly identify the active and inert zones of cell wall growth during bacterial elongation. Within the active zone, the insertion of newly synthesized peptidoglycan occurs homogeneously in the axial direction without twisting of the cell body. Based on the measured parameters, we formulate a Bernoulli shift map model to predict the partitioning of cell wall-anchored proteins following cell division.

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