scholarly journals Enzymes and Mechanisms Employed by Tailed Bacteriophages to Breach the Bacterial Cell Barriers

Viruses ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 396 ◽  
Author(s):  
Sofia Fernandes ◽  
Carlos São-José
Keyword(s):  
Cell Wall ◽  
Host Cell ◽  
Bacterial Cell ◽  
Cell Envelope ◽  
Genetic Material ◽  
Cell Types ◽  
Virus Multiplication ◽  
Virus Particles ◽  
Bacterial Cell Envelope ◽  
A Cell

Monoderm bacteria possess a cell envelope made of a cytoplasmic membrane and a cell wall, whereas diderm bacteria have and extra lipid layer, the outer membrane, covering the cell wall. Both cell types can also produce extracellular protective coats composed of polymeric substances like, for example, polysaccharidic capsules. Many of these structures form a tight physical barrier impenetrable by phage virus particles. Tailed phages evolved strategies/functions to overcome the different layers of the bacterial cell envelope, first to deliver the genetic material to the host cell cytoplasm for virus multiplication, and then to release the virion offspring at the end of the reproductive cycle. There is however a major difference between these two crucial steps of the phage infection cycle: virus entry cannot compromise cell viability, whereas effective virion progeny release requires host cell lysis. Here we present an overview of the viral structures, key protein players and mechanisms underlying phage DNA entry to bacteria, and then escape of the newly-formed virus particles from infected hosts. Understanding the biological context and mode of action of the phage-derived enzymes that compromise the bacterial cell envelope may provide valuable information for their application as antimicrobials.

The outer layer of the cell envelope of Halobacterium halobium

1969 ◽  
Vol 47 (1) ◽  
pp. 71-74 ◽  
Author(s):  
Carolyn L. Marshall ◽  
A. J. Wicken ◽  
A. D. Brown
Keyword(s):  
Cell Wall ◽  
Chemical Analysis ◽  
Outer Layer ◽  
Bacterial Cell ◽  
Cell Walls ◽  
Cell Envelope ◽  
Halobacterium Halobium ◽  
A Cell ◽  
Bacterial Cell Walls

The outer layer of the cell envelope of Halobacterium halobium was isolated after suspending the envelope in either 1 M NaCl or 0.02 M MgCl2. Chemical analysis of the isolated, solubilized outer layer showed it to consist of protein or glycoprotein with about 3% RNA. No free or bound lipid was detected. No cytochromes were present in the outer layer. Components commonly associated with bacterial cell walls were absent.Chemical composition together with the marked instability of the outer layer in a slight ion deficit are not consistent with a function of this layer as a "cell wall" of the organism.

scholarly journals The importance of the bacterial cell wall in uranium(vi) biosorption

2021 ◽  
Author(s):  
Joseph Hufton ◽  
John Harding ◽  
Thomas Smith ◽  
Maria E. Romero-González
Keyword(s):  
Cell Wall ◽  
Bacterial Cell ◽  
Cell Envelope ◽  
Bacterial Cell Wall ◽  
Controlling Factor ◽  
Bacterial Cell Envelope

The bacterial cell envelope, in particular the cell wall, is considered the main controlling factor in the biosorption of aqueous uranium(vi) by microorganisms.

The Biology of Viruses

2019 ◽  
Author(s):  
Anna Jeffery-Smith ◽  
C. Y. William Tong
Keyword(s):  
Nucleic Acid ◽  
Host Cell ◽  
Genetic Material ◽  
Cell Types ◽  
Host Cells ◽  
Host Cell Membrane ◽  
Cell Receptors ◽  
A Cell ◽  
Independent Synthesis ◽  
Different Cell Types

In order to be classified as a virus, certain criteria have to be fulfilled. Viruses must ● Be only capable of growth and multiplication within living cells, i.e. obligate intracellular parasite. Host cells could include humans, animals, insects, plants, protozoa, or even bacteria. ● Have a nucleic acid genome (either RNA or DNA, but not both) surrounded by a protein coat (capsid). ● Have no semipermeable membrane, though some have an envelope formed of phospholipids and proteins. ● Be inert outside of the host cell. Enveloped viruses are susceptible to inactivation by organic solvents such as alcohol. ● Perform replication by independent synthesis of components followed by assembly (c.f. binary fission in bacteria). Viruses are considered as a bundle of genetic programmes encoded in nucleic acids and packaged with a capsid +/ - envelope protein, which can be activated on entry into a host cell (compare this with computer viruses packaged in an enticing way in order to infect and take over control of your PC). Although they share some similarities in their properties, mycoplasma and chlamydia are true bacteria. The virion (assembled infectious particle) consists of viral nucleic acid and capsid. The nucleic acid of a virus can either be ribonucleic acid (RNA) or deoxyribonucleic acid (DNA), and the amount of genetic material varies widely, with some viruses able to encode a few proteins and others having genetic material that encodes hundreds of proteins. In association with the nucleic acid there may be non- structural viral proteins, such as a viral polymerase. The nucleic acid and non- structural proteins are protected by a surrounding layer of capsid proteins. The capsid includes proteins which can attach to host cell receptors. The proteins and the cell receptors to which they bind determine a virus’ tropism, i.e., the ability to bind to and enter different cell types. The term nucleocapsid refers to the nucleic acid core surrounded by capsid protein. Some viruses also have an envelope made up of phospholipids and proteins surrounding the nucleocapsid. This envelope can be formed by the host cell membrane during the process of a virus budding from a cell during replication.

scholarly journals User experience: Using national Cryo EM centers towards studying lipid transport across the bacterial cell envelope

2021 ◽  
Vol 27 (S1) ◽  
pp. 1422-1422
Author(s):  
Gira Bhabha ◽  
Damian Ekiert ◽  
Nicolas Coudray ◽  
Georgia Isom ◽  
Mark MacRae ◽  
...  
Keyword(s):  
User Experience ◽  
Bacterial Cell ◽  
Cell Envelope ◽  
Lipid Transport ◽  
Bacterial Cell Envelope

scholarly journals L-form bacteria, cell walls and the origins of life

Open Biology ◽  
2013 ◽  
Vol 3 (1) ◽  
pp. 120143 ◽  
Author(s):  
Jeff Errington
Keyword(s):  
Cell Wall ◽  
Cell Envelope ◽  
Evolutionary Development ◽  
Last Common Ancestor ◽  
Bacterial Cells ◽  
A Cell ◽  
Evolutionary Radiations ◽  
Key Steps ◽  
Bacterial Domain

The peptidoglycan wall is a defining feature of bacterial cells and was probably already present in their last common ancestor. L-forms are bacterial variants that lack a cell wall and divide by a variety of processes involving membrane blebbing, tubulation, vesiculation and fission. Their unusual mode of proliferation provides a model for primitive cells and is reminiscent of recently developed in vitro vesicle reproduction processes. Invention of the cell wall may have underpinned the explosion of bacterial life on the Earth. Later innovations in cell envelope structure, particularly the emergence of the outer membrane of Gram-negative bacteria, possibly in an early endospore former, seem to have spurned further major evolutionary radiations. Comparative studies of bacterial cell envelope structure may help to resolve the early key steps in evolutionary development of the bacterial domain of life.

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