Mycoplasma Membranes as Models in Membrane Research

Razin, Shmuel

doi:10.1007/978-1-4615-2924-8_1

Cited by 10 publications

(8 citation statements)

References 115 publications

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“…Lacking a cell wall and intracytoplasmic membranes, the mollicutes have only one type of membrane, the plasma membrane. The ease with which this membrane can be isolated and the ability to introduce controlled alterations in its composition have made mycoplasma membranes effective tools in membrane research (356,362). A multiauthored treatise devoted to various aspects of mycoplasma membrane research was published in 1993 (395).…”

Section: Cell Membranementioning

confidence: 99%

Molecular Biology and Pathogenicity of Mycoplasmas

Razin

Yogev

Naot

1998

Microbiol Mol Biol Rev

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1,502

954

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SUMMARY The recent sequencing of the entire genomes of Mycoplasma genitalium and M. pneumoniae has attracted considerable attention to the molecular biology of mycoplasmas, the smallest self-replicating organisms. It appears that we are now much closer to the goal of defining, in molecular terms, the entire machinery of a self-replicating cell. Comparative genomics based on comparison of the genomic makeup of mycoplasmal genomes with those of other bacteria, has opened new ways of looking at the evolutionary history of the mycoplasmas. There is now solid genetic support for the hypothesis that mycoplasmas have evolved as a branch of gram-positive bacteria by a process of reductive evolution. During this process, the mycoplasmas lost considerable portions of their ancestors’ chromosomes but retained the genes essential for life. Thus, the mycoplasmal genomes carry a high percentage of conserved genes, greatly facilitating gene annotation. The significant genome compaction that occurred in mycoplasmas was made possible by adopting a parasitic mode of life. The supply of nutrients from their hosts apparently enabled mycoplasmas to lose, during evolution, the genes for many assimilative processes. During their evolution and adaptation to a parasitic mode of life, the mycoplasmas have developed various genetic systems providing a highly plastic set of variable surface proteins to evade the host immune system. The uniqueness of the mycoplasmal systems is manifested by the presence of highly mutable modules combined with an ability to expand the antigenic repertoire by generating structural alternatives, all compressed into limited genomic sequences. In the absence of a cell wall and a periplasmic space, the majority of surface variable antigens in mycoplasmas are lipoproteins. Apart from providing specific antimycoplasmal defense, the host immune system is also involved in the development of pathogenic lesions and exacerbation of mycoplasma induced diseases. Mycoplasmas are able to stimulate as well as suppress lymphocytes in a nonspecific, polyclonal manner, both in vitro and in vivo. As well as to affecting various subsets of lymphocytes, mycoplasmas and mycoplasma-derived cell components modulate the activities of monocytes/macrophages and NK cells and trigger the production of a wide variety of up-regulating and down-regulating cytokines and chemokines. Mycoplasma-mediated secretion of proinflammatory cytokines, such as tumor necrosis factor alpha, interleukin-1 (IL-1), and IL-6, by macrophages and of up-regulating cytokines by mitogenically stimulated lymphocytes plays a major role in mycoplasma-induced immune system modulation and inflammatory responses.

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Section: Cell Membranementioning

confidence: 99%

Molecular Biology and Pathogenicity of Mycoplasmas

Razin

Yogev

Naot

1998

Microbiol Mol Biol Rev

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1,502

954

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“…7). [29] It has been previously shown that at temperatures above the growth conditions the lipid membrane of microorganisms is in Ld state, [30,31] At temperatures lower than the growth temperature, the membranes of microorganisms are known to undergo a phase transition to a state characterized by a considerably higher, [1,2,3,4,5,6,7] including a microorganism closely related to M. mycoides. [32] Therefore, one should expect this effect to take place also for membranes of M. mycoides.…”

Section: Measuring Viscosity In Biologically Relevant Membranesmentioning

confidence: 99%

New method for high-throughput measurements of viscosity in submicrometer-sized membrane systems

Chwastek

Petrov

Sáenz

2019

Preprint

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In order to unravel the underlying principles of membrane adaptation in small systems like bacterial cells, robust approaches to characterize membrane fluidity are needed. Currently available relevant methods require advanced instrumentation and are not suitable for high throughput settings needed to elucidate the biochemical pathways involved in adaptation. We developed a fast, robust, and financially accessible quantitative method to measure microviscosity of lipid membranes in bulk suspension using a commercially available plate reader. Our approach, which is suitable for high-throughput screening, is based on the simultaneous measurements of absorbance and fluorescence emission of a viscosity-sensitive fluorescent dye DCVJ incorporated into a lipid membrane. We validated our method using artificial membranes with various lipid compositions over a range of temperatures and observed values that were in good agreement with previously published results. Using our approach, we were able to detect a lipid phase transition in the ruminant pathogen Mycoplasma mycoides.

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“…Interference with adherence will thus prevent colonization and infection, and could be a basis for prevention of the disease (Kahane et al, 1982;Razin, 1993). Direct or indirect damage to host tissues due to mycoplasma infection is believed to follow the adherence of mycoplasma to target cells.…”

Section: Mechanisms Of Mycoplasma Pathogenesismentioning

confidence: 99%

Role of phenotypic diversity in pathogenesis of avian mycoplasmosis

Noormohammadi

2007

Avian Pathology

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The interactions between avian mycoplasmas and their host cells are far more complex than might be anticipated from their apparent structural and functional simplicity. Phenotypic diversity in the form of reversible phase variation, antigenic variation or size variation is an adaptive mechanism that enables avian mycoplasmas to survive in a hostile and highly evolved host. Despite significant similarities between major membrane antigens of Mycoplasma gallisepticum and Mycoplasma synoviae, the molecular mechanisms that mediate phenotypic variation in these two pathogens are completely different. Throughout the years, these mechanisms have evolved side by side with their host immune system and provided mycoplasmas the capacity to colonize, invade and persist in an intricate host. In this article, recent advances in the understanding of the molecular mechanisms of phenotypic variation are reviewed, and implications of such variation in pathogenesis of the disease and development of vaccines and diagnostic assays are outlined.

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Mycoplasma Membranes as Models in Membrane Research

Cited by 10 publications

References 115 publications

Molecular Biology and Pathogenicity of Mycoplasmas

Molecular Biology and Pathogenicity of Mycoplasmas

New method for high-throughput measurements of viscosity in submicrometer-sized membrane systems

Role of phenotypic diversity in pathogenesis of avian mycoplasmosis

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