scholarly journals LuxR-family ‘solos’: bachelor sensors/regulators of signalling molecules

Microbiology ◽  
2009 ◽  
Vol 155 (5) ◽  
pp. 1377-1385 ◽  
Author(s):  
Sujatha Subramoni ◽  
Vittorio Venturi
Keyword(s):  
Bacterial Species ◽  
Signalling Molecules ◽  
Acylhomoserine Lactone ◽  
Family Protein ◽  
Density Response ◽  
A Cell ◽  
Biochemical Mechanisms ◽  
Molecular And Biochemical Mechanisms ◽  
Interkingdom Communication ◽  
Mixed Communities

N-Acylhomoserine lactone (AHL) quorum-sensing (QS) signalling is the best-understood chemical language in proteobacteria. In the last 15 years a large amount of research in several bacterial species has revealed in detail the genetic, molecular and biochemical mechanisms underlying AHL signalling. These studies have revealed the role played by protein pairs of the AHL synthase belonging to the LuxI family and cognate LuxR-family AHL sensor–regulator. Proteobacteria however commonly possess a QS LuxR-family protein for which there is no obvious cognate LuxI synthase; these proteins are found in bacteria which possess a complete AHL QS system(s) as well as in bacteria that do not. Scientists are beginning to address the roles played by these proteins and it is emerging that they could allow bacteria to respond to endogenous and exogenous signals produced by their neighbours. AHL QS research thus far has mainly focused on a cell-density response involving laboratory monoculture studies. Recent findings on the role played by the unpaired LuxR-family proteins highlight the need to address bacterial behaviour and response to signals in mixed communities. Here we review recent progress with respect to these LuxR proteins, which we propose to call LuxR ‘solos’ since they act on their own without the need for a cognate signal generator. Initial investigations have revealed that LuxR solos have diverse roles in bacterial interspecies and interkingdom communication.

scholarly journals Environmental modification via a quorum sensing molecule influences the social landscape of siderophore production

2017 ◽  
Vol 284 (1852) ◽  
pp. 20170200 ◽  
Author(s):  
Roman Popat ◽  
Freya Harrison ◽  
Ana C. da Silva ◽  
Scott A. S. Easton ◽  
Luke McNally ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Public Goods ◽  
Bacterial Species ◽  
Relative Fitness ◽  
Iron Starvation ◽  
Signal Molecule ◽  
Signalling Molecules ◽  
Signalling Molecule ◽  
The Impact ◽  
Social Trait

Bacteria produce a wide variety of exoproducts that favourably modify their environment and increase their fitness. These are often termed ‘public goods’ because they are costly for individuals to produce and can be exploited by non-producers (cheats). The outcome of conflict over public goods is dependent upon the prevailing environment and the phenotype of the individuals in competition. Many bacterial species use quorum sensing (QS) signalling molecules to regulate the production of public goods. QS, therefore, determines the cooperative phenotype of individuals, and influences conflict over public goods. In addition to their regulatory functions, many QS molecules have additional properties that directly modify the prevailing environment. This leads to the possibility that QS molecules could influence conflict over public goods indirectly through non-signalling effects, and the impact of this on social competition has not previously been explored. The Pseudomonas aeruginosa QS signal molecule PQS is a powerful chelator of iron which can cause an iron starvation response. Here, we show that PQS stimulates a concentration-dependent increase in the cooperative production of iron scavenging siderophores, resulting in an increase in the relative fitness of non-producing siderophore cheats. This is likely due to an increased cost of siderophore output by producing cells and a concurrent increase in the shared benefits, which accrue to both producers and cheats. Although PQS can be a beneficial signalling molecule for P. aeruginosa , our data suggest that it can also render a siderophore-producing population vulnerable to competition from cheating strains. More generally, our results indicate that the production of one social trait can indirectly affect the costs and benefits of another social trait.

Archaeal biofilms: widespread and complex

2013 ◽  
Vol 41 (1) ◽  
pp. 393-398 ◽  
Author(s):  
Sabrina Fröls
Keyword(s):  
Biofilm Formation ◽  
Extracellular Polymeric Substances ◽  
Bacterial Species ◽  
Surface Adhesion ◽  
Form Complex ◽  
Abiotic Surfaces ◽  
Archaeal Species ◽  
Physical And Chemical ◽  
Insight Into ◽  
Mixed Communities

Biofilms or multicellular structures become accepted as the dominant microbial lifestyle in Nature, but in the past they were only studied extensively in bacteria. Investigations on archaeal monospecies cultures have shown that many archaeal species are able to adhere on biotic and abiotic surfaces and form complex biofilm structures. Biofilm-forming archaea were identified in a broad range of extreme and moderate environments. Natural biofilms observed are mostly mixed communities composed of archaeal and bacterial species of various abundances. The physiological functions of the archaea identified in such mixed communities suggest a significant impact on the biochemical cycles maintaining the flow and recycling of the nutrients on earth. Therefore it is of high interest to investigate the characteristics and mechanisms underlying the archaeal biofilm formation. In the present review, I summarize and discuss the present investigations of biofilm-forming archaeal species, i.e. their diverse biofilm architectures in monospecies or mixed communities, the identified EPSs (extracellular polymeric substances), archaeal structures mediating surface adhesion or cell–cell connections, and the response to physical and chemical stressors implying that archaeal biofilm formation is an adaptive reaction to changing environmental conditions. A first insight into the molecular differentiation of cells within archaeal biofilms is given.

Atmospheric reactive oxygen species and some aspects of the antiviral protection of the respiratory epithelium

2021 ◽  
Vol 67 (5) ◽  
pp. 383-393
Author(s):  
V.V. Salmin ◽  
A.V. Morgun ◽  
R.Ya. Olovyannikova ◽  
V.A. Kutyakov ◽  
E.V. Lychkovskaya ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Expression Profiles ◽  
Respiratory Epithelium ◽  
Antibacterial Effects ◽  
Pharmacological Agents ◽  
Pathological Conditions ◽  
Lactoperoxidase System ◽  
Biochemical Mechanisms ◽  
Atmospheric Factors ◽  
Molecular And Biochemical Mechanisms

The review focuses on molecular and biochemical mechanisms of nonspecific protection of respiratory epithelium. The authors provide a comprehensive analysis of up-to-date data on the activity of the lactoperoxidase system expressed on the surface of the respiratory epithelium which provides the generation of hypothiocyanate and hypoiodite in the presence of locally produced or inhaled hydrogen peroxide. Molecular mechanisms of production of active compounds with antiviral and antibacterial effects, expression profiles of enzymes, transporters and ion channels involved in the generation of hypothiocyanite and hypoiodate in the mucous membrane of the respiratory system in physiological and pathological conditions (inflammation) are discussed. In the context of antibacterial and antiviral defense special attention is paid to recent data confirming the effects of atmospheric air composition on the efficiency of hypothiocyanite and hypoiodate synthesis in the respiratory epithelium. The causes and outcomes of lactoperoxidase system impairment due to the action of atmospheric factors are discussed in the context of controlling the sensitivity of the epithelium to the action of bacterial agents and viruses. Restoration of the lactoperoxidase system activity can be achieved by application of pharmacological agents aimed to compensate for the lack of halides in tissues, and by the control of chemical composition of the inhaled air.

F-actin as a functional target for retro-retinoids: a potential role in anhydroretinol-triggered cell death

1999 ◽  
Vol 112 (15) ◽  
pp. 2521-2528 ◽  
Author(s):  
I. Korichneva ◽  
U. Hammerling
Keyword(s):  
Cell Death ◽  
Early Event ◽  
Pattern Reversal ◽  
Cell Periphery ◽  
Growth And Survival ◽  
Signalling Molecules ◽  
Herbimycin A ◽  
Morphological Studies ◽  
A Cell ◽  
Survival Potential

The retro-retinoids, metabolites of vitamin A (retinol), belong to a family of lipophilic signalling molecules implicated in regulation of cell growth and survival. Growth-promoting properties have been ascribed to 14-hydroxy-retro-retinol (14HRR), while anhydroretinol (AR) was discovered to act as a natural antagonist triggering growth arrest and death by apoptosis. Based on morphological studies and inhibition of apoptosis by the kinase blocker, herbimycin A, it has been suggested that retro-retinoids exhibit their function in the cytosolic compartment. F-actin emerged as a functional target for retro-retinoid action. By FACS analysis and fluorescence microscopy of phalloidin-FITC labeled cells we demonstrated that F-actin reorganization was an early event in AR-triggered apoptosis. Fluorescence images of AR-treated fibroblasts displayed short, thick, stick-like and punctate structures, and membrane ruffles at the cell periphery along with an increased diffuse staining pattern. Reversal of the AR effect by 14HRR or retinol indicates that F-actin is a common site for regulation by retro-retinoids. Inhibition of both cell death and actin depolymerisation by bcl-2 implies that cytoskeleton reorganization is downstream of bcl-2-related processes. Furthermore, stabilization of microfilaments by jasplakinolide increased the survival potential of AR treated cells, while weakening the cytoskeleton by cytochalasin B abetted apoptosis. Thus the cytoskeleton is an important way station in a communication network that decides whether a cell should live or die.

scholarly journals Brain manganese and the balance between essential roles and neurotoxicity

2020 ◽  
Vol 295 (19) ◽  
pp. 6312-6329 ◽  
Author(s):  
Rekha C. Balachandran ◽  
Somshuvra Mukhopadhyay ◽  
Danielle McBride ◽  
Jennifer Veevers ◽  
Fiona E. Harrison ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Normal Development ◽  
The Body ◽  
Neurological Dysfunction ◽  
Cellular Transport ◽  
Brain Health ◽  
Biochemical Mechanisms ◽  
Molecular And Biochemical Mechanisms ◽  
Neuronal Physiology ◽  
The Brain

Manganese (Mn) is an essential micronutrient required for the normal development of many organs, including the brain. Although its roles as a cofactor in several enzymes and in maintaining optimal physiology are well-known, the overall biological functions of Mn are rather poorly understood. Alterations in body Mn status are associated with altered neuronal physiology and cognition in humans, and either overexposure or (more rarely) insufficiency can cause neurological dysfunction. The resultant balancing act can be viewed as a hormetic U-shaped relationship for biological Mn status and optimal brain health, with changes in the brain leading to physiological effects throughout the body and vice versa. This review discusses Mn homeostasis, biomarkers, molecular mechanisms of cellular transport, and neuropathological changes associated with disruptions of Mn homeostasis, especially in its excess, and identifies gaps in our understanding of the molecular and biochemical mechanisms underlying Mn homeostasis and neurotoxicity.

scholarly journals Gut Microbiota Metabolism and Interaction with Food Components

2020 ◽  
Vol 21 (10) ◽  
pp. 3688 ◽  
Author(s):  
Pamela Vernocchi ◽  
Federica Del Chierico ◽  
Lorenza Putignani
Keyword(s):  
Gut Microbiota ◽  
Disease Onset ◽  
Human Gut ◽  
Food Components ◽  
Host Health ◽  
Wide Variability ◽  
Gut Microbe ◽  
A Cell ◽  
Health And Disease ◽  
Biochemical Mechanisms

The human gut contains trillions of microbes that play a central role in host biology, including the provision of key nutrients from the diet. Food is a major source of precursors for metabolite production; in fact, diet modulates the gut microbiota (GM) as the nutrients, derived from dietary intake, reach the GM, affecting both the ecosystem and microbial metabolic profile. GM metabolic ability has an impact on human nutritional status from childhood. However, there is a wide variability of dietary patterns that exist among individuals. The study of interactions with the host via GM metabolic pathways is an interesting field of research in medicine, as microbiota members produce myriads of molecules with many bioactive properties. Indeed, much evidence has demonstrated the importance of metabolites produced by the bacterial metabolism from foods at the gut level that dynamically participate in various biochemical mechanisms of a cell as a reaction to environmental stimuli. Hence, the GM modulate homeostasis at the gut level, and the alteration in their composition can concur in disease onset or progression, including immunological, inflammatory, and metabolic disorders, as well as cancer. Understanding the gut microbe–nutrient interactions will increase our knowledge of how diet affects host health and disease, thus enabling personalized therapeutics and nutrition.

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