scholarly journals Physical basis for the adaptive flexibility of Bacillus spore coats

2012 ◽  
Vol 9 (76) ◽  
pp. 3156-3160 ◽  
Author(s):  
Ozgur Sahin ◽  
Ee Hou Yong ◽  
Adam Driks ◽  
L. Mahadevan
Keyword(s):  
Metabolic Activity ◽  
Mechanical Response ◽  
Genetic Material ◽  
Biological Functions ◽  
Bacillus Spore ◽  
Dormant Cells ◽  
Complex Protein ◽  
Incompatible Characteristics ◽  
Adaptive Materials ◽  
Protein Shell

Bacillus spores are highly resistant dormant cells formed in response to starvation. The spore is surrounded by a structurally complex protein shell, the coat, which protects the genetic material. In spite of its dormancy, once nutrient is available (or an appropriate physical stimulus is provided) the spore is able to resume metabolic activity and return to vegetative growth, a process requiring the coat to be shed. Spores dynamically expand and contract in response to humidity, demanding that the coat be flexible. Despite the coat's critical biological functions, essentially nothing is known about the design principles that allow the coat to be tough but also flexible and, when metabolic activity resumes, to be efficiently shed. Here, we investigated the hypothesis that these apparently incompatible characteristics derive from an adaptive mechanical response of the coat. We generated a mechanical model predicting the emergence and dynamics of the folding patterns uniformly seen in Bacillus spore coats. According to this model, spores carefully harness mechanical instabilities to fold into a wrinkled pattern during sporulation. Owing to the inherent nonlinearity in their formation, these wrinkles persist during dormancy and allow the spore to accommodate changes in volume without compromising structural and biochemical integrity. This characteristic of the spore and its coat may inspire design of adaptive materials.

scholarly journals The N Terminus of the PduB Protein Binds the Protein Shell of the Pdu Microcompartment to Its Enzymatic Core

2017 ◽  
Vol 199 (8) ◽  
Author(s):  
Brent P. Lehman ◽  
Chiranjit Chowdhury ◽  
Thomas A. Bobik
Keyword(s):  
Amino Acids ◽  
Protein Complexes ◽  
Critical Role ◽  
Chemical Production ◽  
Protein Subunits ◽  
Bacterial Microcompartments ◽  
Shell Protein ◽  
N Terminus ◽  
Complex Protein ◽  
Protein Shell

ABSTRACT Bacterial microcompartments (MCPs) are extremely large proteinaceous organelles that consist of an enzymatic core encapsulated within a complex protein shell. A key question in MCP biology is the nature of the interactions that guide the assembly of thousands of protein subunits into a well-ordered metabolic compartment. In this report, we show that the N-terminal 37 amino acids of the PduB protein have a critical role in binding the shell of the 1,2-propanediol utilization (Pdu) microcompartment to its enzymatic core. Several mutations were constructed that deleted short regions of the N terminus of PduB. Growth tests indicated that three of these deletions were impaired MCP assembly. Attempts to purify MCPs from these mutants, followed by gel electrophoresis and enzyme assays, indicated that the protein complexes isolated consisted of MCP shells depleted of core enzymes. Electron microscopy substantiated these findings by identifying apparently empty MCP shells but not intact MCPs. Analyses of 13 site-directed mutants indicated that the key region of the N terminus of PduB required for MCP assembly is a putative helix spanning residues 6 to 18. Considering the findings presented here together with prior work, we propose a new model for MCP assembly. IMPORTANCE Bacterial microcompartments consist of metabolic enzymes encapsulated within a protein shell and are widely used to optimize metabolic process. Here, we show that the N-terminal 37 amino acids of the PduB shell protein are essential for assembly of the 1,2-propanediol utilization microcompartment. The results indicate that it plays a key role in binding the outer shell to the enzymatic core. We propose that this interaction might be used to define the relative orientation of the shell with respect to the core. This finding is of fundamental importance to our understanding of microcompartment assembly and may have application to engineering microcompartments as nanobioreactors for chemical production.

scholarly journals Biological Functions of Type II Toxin-Antitoxin Systems in Bacteria

2021 ◽  
Vol 9 (6) ◽  
pp. 1276
Author(s):  
Muhammad Kamruzzaman ◽  
Alma Y. Wu ◽  
Jonathan R. Iredell
Keyword(s):  
Genetic Material ◽  
Type Ii ◽  
Biological Functions ◽  
Bacterial Physiology ◽  
Major Function ◽  
Maintenance System ◽  
System A ◽  
Bacterial Chromosomes ◽  
Bona Fide ◽  
Bacterial Type

After the first discovery in the 1980s in F-plasmids as a plasmid maintenance system, a myriad of toxin-antitoxin (TA) systems has been identified in bacterial chromosomes and mobile genetic elements (MGEs), including plasmids and bacteriophages. TA systems are small genetic modules that encode a toxin and its antidote and can be divided into seven types based on the nature of the antitoxin molecules and their mechanism of action to neutralise toxins. Among them, type II TA systems are widely distributed in chromosomes and plasmids and the best studied so far. Maintaining genetic material may be the major function of type II TA systems associated with MGEs, but the chromosomal TA systems contribute largely to functions associated with bacterial physiology, including the management of different stresses, virulence and pathogenesis. Due to growing interest in TA research, extensive work has been conducted in recent decades to better understand the physiological roles of these chromosomally encoded modules. However, there are still controversies about some of the functions associated with different TA systems. This review will discuss the most current findings and the bona fide functions of bacterial type II TA systems.

Work efficiently, like bacteriophages with icosahedral symmetry

2020 ◽  
pp. 201-210
Author(s):  
Susan D'Agostino
Keyword(s):  
Genetic Material ◽  
Icosahedral Symmetry ◽  
Mathematics Students ◽  
Small Virus ◽  
Protein Shell ◽  
Technical Terms

“Work efficiently, like bacteriophages with icosahedral symmetry” explains in non-technical terms how an exceptionally small virus that infects bacteria uses its geometry to efficiently encode instructions for assembling the protein shell that stores its genetic material. Readers may cut out a template and construct a model of the bacteriophage’s icosahedron-shaped head. In addition, numerous hand-drawn sketches illustrate the mathematical symmetries of the bacteriophage’s replication. Mathematics students and enthusiasts are encouraged to learn a lesson from the bacteriophage by economizing time and effort in mathematical and life pursuits. At the chapter’s end, readers may check their understanding by working on a problem. A solution is provided.

scholarly journals Muropeptides Stimulate Growth Resumption from Stationary Phase in Escherichia coli

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Arvi Jõers ◽  
Kristiina Vind ◽  
Sara B. Hernández ◽  
Regina Maruste ◽  
Marta Pereira ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Metabolic Activity ◽  
Immune Cells ◽  
Microbial Growth ◽  
Bacterial Species ◽  
Peptide Bond ◽  
Bacterial Spores ◽  
Dormant Cells ◽  
Growth Promoting

AbstractWhen nutrients run out, bacteria enter a dormant metabolic state. This low or undetectable metabolic activity helps bacteria to preserve their scant reserves for the future needs, yet it also diminishes their ability to scan the environment for new growth-promoting substrates. However, neighboring microbial growth is a reliable indicator of a favorable environment and can thus serve as a cue for exiting dormancy. Here we report that for Escherichia coli and Pseudomonas aeruginosa this cue is provided by the basic peptidoglycan unit (i.e. muropeptide). We show that several forms of muropeptides from a variety of bacterial species can stimulate growth resumption of dormant cells and the sugar – peptide bond is crucial for this activity. These results, together with previous research that identifies muropeptides as a germination signal for bacterial spores, and their detection by mammalian immune cells, show that muropeptides are a universal cue for bacterial growth.

scholarly journals The Bacillus Spore Coat

2004 ◽  
Vol 94 (11) ◽  
pp. 1249-1251 ◽  
Author(s):  
Adam Driks
Keyword(s):  
Cross Section ◽  
Surface Characterization ◽  
Cell Types ◽  
Distinct Pattern ◽  
Spore Coat ◽  
Dormant Cell ◽  
Future Directions ◽  
Bacillus Spore ◽  
Protein Shell

Bacilli, which are abundant in the soil, form highly resistant dormant cell types, called spores, in response to starvation. The spore is organized into a series of concentrically arranged structures, each of which contribute in a different way to resistance against environmental stress. In certain bacteria, including Bacillus subtilis, the outermost of these structures is a multilayered protein shell, called the coat. The coat is both an armor plating and, almost certainly, possesses enzymatic activities, allowing it to have active roles as well. Assembly of the proteins comprising the coat is carefully controlled during spore assembly, resulting in a distinct pattern of layers, seen in cross section, and a discreet pattern of ridges on the surface. Although our understanding of spore coat composition and assembly is deepening, we still know little about the roles of the coat in interactions between spores and other organisms, particularly in the soil. Critical future directions for spore coat research include continued identification of the proteins that comprise the coat surface, characterization of the global chemical characteristics of this surface, and elucidation of how these features impact on other organisms in the soil.

Ultrastructure and Drug Metabolism in the Developing Guinea Pig

1973 ◽  
Vol 31 ◽  
pp. 538-539
Author(s):  
W. Kuenzig ◽  
M. Boublik ◽  
J.J. Kamm ◽  
J.J. Burns
Keyword(s):  
Guinea Pig ◽  
Metabolic Activity ◽  
Animal Species ◽  
Adult Animal ◽  
Smooth Endoplasmic Reticulum ◽  
Fetal Life ◽  
Mixed Function Oxidase ◽  
Cytochrome P 450 ◽  
Microsomal Mixed Function Oxidase ◽  
Mixed Function Oxidase Activity

Unlike a variety of other animal species, such as the rabbit, mouse or rat, the guinea pig has a relatively long gestation period and is a more fully developed animal at birth. Kuenzig et al. reported that drug metabolic activity which increases very slowly during fetal life, increases rapidly after birth. Hepatocytes of a 3-day old neonate metabolize drugs and reduce cytochrome P-450 at a rate comparable to that observed in the adult animal. Moreover the administration of drugs like phenobarbital to pregnant guinea pigs increases the microsomal mixed function oxidase activity already in the fetus.Drug metabolic activity is, generally, localized within the smooth endoplasmic reticulum (SER) of the hepatocyte.

Fibroblasts During Hypertrophic Scar Formation and Resolution

1973 ◽  
Vol 31 ◽  
pp. 428-429
Author(s):  
C. W. Kischer
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Cell Proliferation ◽  
Fine Structure ◽  
Metabolic Activity ◽  
Hypertrophic Scar ◽  
Normal Skin ◽  
Ground Substance ◽  
Hypertrophic Scars ◽  
Scanning Electron

The morphology of the fibroblasts changes markedly as the healing period from burn wounds progresses, through development of the hypertrophic scar, to resolution of the scar by a self-limiting process of maturation or therapeutic resolution. In addition, hypertrophic scars contain an increased cell proliferation largely made up of fibroblasts. This tremendous population of fibroblasts seems congruous with the abundance of collagen and ground substance. The fine structure of these cells should reflect some aspects of the metabolic activity necessary for production of the scar, and might presage the stage of maturation.A comparison of the fine structure of the fibroblasts from normal skin, different scar types, and granulation tissue has been made by transmission (TEM) and scanning electron microscopy (SEM).

Ultrastructural aspects of gymnosperms reproductive organs tissues due to their functional condition

1978 ◽  
Vol 36 (2) ◽  
pp. 440-441
Author(s):  
G. M. Kozubov
Keyword(s):  
Metabolic Activity ◽  
Functional Condition ◽  
Reproductive Organs ◽  
Considerable Change ◽  
Complicated Structure ◽  
Tetrad Stage ◽  
Ubisch Bodies ◽  
Similar Organization ◽  
Female Reproductive Organs ◽  
High Metabolic Activity

The ultrastructure of reproductive organs of pine, spruce, larch and ginkgo was investigated. It was found that the male reproductive organs possess similar organization. The most considerable change in the ultrastructure of the microsporocytes occur in meiosis. Sporoderm is being laid at the late tetrad stage. The cells of the male gameto-phyte are distinguished according to the metabolic activity of the or- ganells. They are most weakly developed in the spermiogenic cell. Ta-petum of the gymnosperms is of the periplasmodic - secretorial type. The Ubisch bodies which possess similar structure in the types investigated but are specific in details in different species are produced in tapetum.Parietal and subepidermal layers are distinguished for their high metabolic activity and are capable of the autonomous photosynthesis. Female reproductive organs differ more greatly in their struture and have the most complicated structure in primitive groups. On the first stages of their formation the inner cells of nucellus are transformed into the nucellar tapetum in which the structures similar to the Ubisch bodies taking part in the formation of the sporoderm of female gametophyte have been found.

Comparison of Substructures Between Uniaxial and Biaxial Deformation in 1100-0 Aluminum

1981 ◽  
Vol 39 ◽  
pp. 52-53
Author(s):  
D. L. Rohr ◽  
S. S. Hecker
Keyword(s):  
Plastic Strain ◽  
Cell Walls ◽  
Room Temperature ◽  
Mechanical Response ◽  
Biaxial Tension ◽  
Initial Deformation ◽  
Uniaxial Deformation ◽  
Biaxial Deformation ◽  
Stress States ◽  
Comprehensive Study

As part of a comprehensive study of microstructural and mechanical response of metals to uniaxial and biaxial deformations, the development of substructure in 1100 A1 has been studied over a range of plastic strain for two stress states.Specimens of 1100 aluminum annealed at 350 C were tested in uniaxial (UT) and balanced biaxial tension (BBT) at room temperature to different strain levels. The biaxial specimens were produced by the in-plane punch stretching technique. Areas of known strain levels were prepared for TEM by lapping followed by jet electropolishing. All specimens were examined in a JEOL 200B run at 150 and 200 kV within 24 to 36 hours after testing.The development of the substructure with deformation is shown in Fig. 1 for both stress states. Initial deformation produces dislocation tangles, which form cell walls by 10% uniaxial deformation, and start to recover to form subgrains by 25%. The results of several hundred measurements of cell/subgrain sizes by a linear intercept technique are presented in Table I.

Head Size and DNA Content in Bacteriophage T4

1972 ◽  
Vol 30 ◽  
pp. 200-201
Author(s):  
Fred Eiserling ◽  
A. H. Doermann ◽  
Linde Boehner
Keyword(s):  
Electron Microscopy ◽  
Dna Content ◽  
Bacteriophage T4 ◽  
Head Size ◽  
Virus Particles ◽  
Altered Protein ◽  
A Cell ◽  
Bacterial Viruses ◽  
A Site ◽  
Protein Shell

The control of form or shape inheritance can be approached by studying the morphogenesis of bacterial viruses. Shape variants of bacteriophage T4 with altered protein shell (capsid) size and nucleic acid (DNA) content have been found by electron microscopy, and a mutant (E920g in gene 66) controlling head size has been described. This mutant produces short-headed particles which contain 2/3 the normal DNA content and which are non-viable when only one particle infects a cell (Fig. 1).We report here the isolation of a new mutant (191c) which also appears to be in gene 66 but at a site distinct from E920g. The most striking phenotype of the mutant is the production of about 10% of the phage yield as “giant” virus particles, from 3 to 8 times longer than normal phage (Fig. 2).

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