Structure and function of the important internalins of Listeria monocytogenes

2021 ◽  
Vol 22 ◽  
Author(s):  
Shabir Ahmad Mir
Keyword(s):  
Listeria Monocytogenes ◽  
Virulence Factors ◽  
Causative Agent ◽  
Structure And Function ◽  
Intracellular Bacterium ◽  
Infection Cycle ◽  
Current Review ◽  
Functional Aspects ◽  
Structural Details ◽  
And Function

: Listeria monocytogenes, a facultative intracellular gram-positive pathogen, is the causative agent of the disease listeriosis. The virulence of this intracellular bacterium is dependent on the coordinated activity of various bacterial factors, which are in turn tightly controlled by a specific set of regulators. The arsenal of virulence factors employed by L. monocytogenes for its infection cycle is available in the literature. Although the internalins of L. monocytogenes have been studied in detail their structural details are currently scattered and fragmented. Therefore, in the current review, we provide a brief account of the existing knowledge on structural details of the key internalins of L. monocytogenes and also highlight the recent advances in their functional aspects.

scholarly journals Molecular Mechanisms and Therapeutics for SBMA/Kennedy’s Disease

2019 ◽  
Vol 16 (4) ◽  
pp. 928-947 ◽  
Author(s):  
Frederick J. Arnold ◽  
Diane E. Merry
Keyword(s):  
Motor Neurons ◽  
Molecular Mechanisms ◽  
Muscular Atrophy ◽  
Structure And Function ◽  
Loss Of Function ◽  
Mechanisms Of Toxicity ◽  
Current Review ◽  
And Function ◽  
Positive Results ◽  
Polyq Expansion

Abstract Spinal and bulbar muscular atrophy (SBMA) is a neuromuscular disease caused by a polyglutamine (polyQ) expansion in the androgen receptor (AR). Despite the fact that the monogenic cause of SBMA has been known for nearly 3 decades, there is no effective treatment for this disease, underscoring the complexity of the pathogenic mechanisms that lead to a loss of motor neurons and muscle in SBMA patients. In the current review, we provide an overview of the system-wide clinical features of SBMA, summarize the structure and function of the AR, discuss both gain-of-function and loss-of-function mechanisms of toxicity caused by polyQ-expanded AR, and describe the cell and animal models utilized in the study of SBMA. Additionally, we summarize previously conducted clinical trials which, despite being based on positive results from preclinical studies, proved to be largely ineffective in the treatment of SBMA; nonetheless, these studies provide important insights as researchers develop the next generation of therapies.

Calycinal trichomes in Ipomoea cairica (Convolvulaceae): ontogenesis, structure and functional aspects

2011 ◽  
Vol 59 (1) ◽  
pp. 91 ◽  
Author(s):  
Elder Antônio Sousa Paiva ◽  
Luiza Coutinho Martins
Keyword(s):  
Electron Microscopy ◽  
Developmental Stages ◽  
Glandular Trichomes ◽  
Structure And Function ◽  
Short Stalk ◽  
Transmission Electron ◽  
Functional Aspects ◽  
Acidic Polysaccharides ◽  
Low Humidity ◽  
And Function

The presence of calycinal trichomes in Ipomoea has been neglected, which renders the interpretation of their functions difficult. The present work aims to characterise the structure, as well as the composition of the secretion of calycinal trichomes in Ipomoea cairica, in order to establish a relationship between their structure and function. Samples of floral buds at different developmental stages and sepals from fruits were collected and fixed for study under light as well as under scanning and transmission electron microscopy. The calyx of I. cairica is persistent and presents glandular trichomes which produce acidic polysaccharides. The trichomes are peltate and consist of a short stalk and a pluricellular secretory portion. The cells from the secretory portion contain a dense and organelle-rich cytoplasm. The fresh secretion is hyaline and fluid, but solidifies when exposed to low humidity, taking on a crystalline and fragile aspect, and they return to a gel state when in the presence of water. The calycinal trichomes in I. cairica show great structural and ultrastructural similarities to colleters and can be considered functionally analogous. The secretion, which is highly hygroscopic, spreads along the surface of the corolla and of the fruit, apparently protecting these structures against desiccation.

scholarly journals Tales from topographic oceans: topologically associated domains and cancer

2019 ◽  
Vol 26 (11) ◽  
pp. R611-R626 ◽  
Author(s):  
Moray J Campbell
Keyword(s):  
Ovarian Cancer ◽  
Cell Nucleus ◽  
Structure And Function ◽  
Future Directions ◽  
Chromatin Interactions ◽  
Sharp Focus ◽  
Current Review ◽  
Topologically Associated Domains ◽  
Altered Regulation ◽  
And Function

The 3D organization of the genome within the cell nucleus has come into sharp focus over the last decade. This has largely arisen because of the application of genomic approaches that have revealed numerous levels of genomic and chromatin interactions, including topologically associated domains (TADs). The current review examines how these domains were identified, are organized, how their boundaries arise and are regulated, and how genes within TADs are coordinately regulated. There are many examples of the disruption to TAD structure in cancer and the altered regulation, structure and function of TADs are discussed in the context of hormone responsive cancers, including breast, prostate and ovarian cancer. Finally, some aspects of the statistical insight and computational skills required to interrogate TAD organization are considered and future directions discussed.

scholarly journals Characterization and Genetic Diversity of Listeria monocytogenes Isolated from Cattle Abortions in Latvia, 2013–2018

2021 ◽  
Vol 8 (9) ◽  
pp. 195
Author(s):  
Žanete Šteingolde ◽  
Irēna Meistere ◽  
Jeļena Avsejenko ◽  
Juris Ķibilds ◽  
Ieva Bergšpica ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Listeria Monocytogenes ◽  
Virulence Factors ◽  
Causative Agent ◽  
Animal Species ◽  
Clonal Complex ◽  
The Third ◽  
Wide Range ◽  
Sequence Types

Listeria monocytogenes can cause disease in humans and in a wide range of animal species, especially in farm ruminants. The aim of the study was to determine the prevalence and genetic diversity of L. monocytogenes related to 1185 cattle abortion cases in Latvia during 2013–2018. The prevalence of L. monocytogenes among cattle abortions was 16.1% (191/1185). The seasonality of L. monocytogenes abortions was observed with significantly higher occurrence (p < 0.01) in spring (March–May). In 61.0% of the cases, the affected cattle were under four years of age. L. monocytogenes abortions were observed during the third (64.6%) and second (33.3%) trimesters of gestation. Overall, 27 different sequence types (ST) were detected, and four of them, ST29 (clonal complex, CC29), ST37 (CC37), ST451 (CC11) and ST7 (CC7), covered more than half of the L. monocytogenes isolates. Key virulence factors like the prfA-dependent virulence cluster and inlA, inlB were observed in all the analyzed isolates, but lntA, inlF, inlJ, vip were associated with individual sequence types. Our results confirmed that L. monocytogenes is the most important causative agent of cattle abortions in Latvia and more than 20 different STs were observed in L. monocytogenes abortions in cattle.

The gastroenterological manifestations of AIDS and HIV infection

1986 ◽  
Vol 72 (3) ◽  
pp. 129-134
Author(s):  
A. R. O. Miller
Keyword(s):  
Hiv Infection ◽  
Causative Agent ◽  
Structure And Function ◽  
Aids Patients ◽  
Clinical Consequences ◽  
And Function ◽  
Gastrointestinal Upset

AbstractDisturbance of gastrointestinal structure and function is common in AIDS patients and may be due to infection, neoplasia or other, as yet unidentified factors. Gastrointestinal upset also occurs in individuals who have been infected with the causative agent of AIDS but have not developed clinical consequences severe enough to define them as having AIDS. This review examines the various disease processes which can affect the gut in these groups.

scholarly journals Pneumococcal Virulence Factors: Structure and Function

2001 ◽  
Vol 65 (2) ◽  
pp. 187-207 ◽  
Author(s):  
Mark J. Jedrzejas
Keyword(s):  
Virulence Factors ◽  
Surface Antigen ◽  
Pneumococcal Disease ◽  
Protein A ◽  
The Elderly ◽  
Structure And Function ◽  
Structural Level ◽  
Hyaluronate Lyase ◽  
Antigen A ◽  
And Function

SUMMARY The overall goal for this review is to summarize the current body of knowledge about the structure and function of major known antigens of Streptococcus pneumoniae, a major gram-positive bacterial pathogen of humans. This information is then related to the role of these proteins in pneumococcal pathogenesis and in the development of new vaccines and/or other antimicrobial agents. S. pneumoniae is the most common cause of fatal community-acquired pneumonia in the elderly and is also one of the most common causes of middle ear infections and meningitis in children. The present vaccine for the pneumococcus consists of a mixture of 23 different capsular polysaccharides. While this vaccine is very effective in young adults, who are normally at low risk of serious disease, it is only about 60% effective in the elderly. In children younger than 2 years the vaccine is ineffective and is not recommended due to the inability of this age group to mount an antibody response to the pneumococcal polysaccharides. Antimicrobial drugs such as penicillin have diminished the risk from pneumococcal disease. Several pneumococcal proteins including pneumococcal surface proteins A and C, hyaluronate lyase, pneumolysin, autolysin, pneumococcal surface antigen A, choline binding protein A, and two neuraminidase enzymes are being investigated as potential vaccine or drug targets. Essentially all of these antigens have been or are being investigated on a structural level in addition to being characterized biochemically. Recently, three-dimensional structures for hyaluronate lyase and pneumococcal surface antigen A became available from X-ray crystallography determinations. Also, modeling studies based on biophysical measurements provided more information about the structures of pneumolysin and pneumococcal surface protein A. Structural and biochemical studies of these pneumococcal virulence factors have facilitated the development of novel antibiotics or protein antigen-based vaccines as an alternative to polysaccharide-based vaccines for the treatment of pneumococcal disease.

scholarly journals Structure and Function of the T4 Spackle Protein Gp61.3

Viruses ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1070
Author(s):  
Shuji Kanamaru ◽  
Kazuya Uchida ◽  
Mai Nemoto ◽  
Alec Fraser ◽  
Fumio Arisaka ◽  
...  
Keyword(s):  
Phage Particle ◽  
Bacteriophage T4 ◽  
Structure And Function ◽  
Lysozyme Activity ◽  
T4 Lysozyme ◽  
Infection Cycle ◽  
Active Site Cleft ◽  
Targeting Peptide ◽  
And Function ◽  
Peptidoglycan Layer

The bacteriophage T4 genome contains two genes that code for proteins with lysozyme activity—e and 5. Gene e encodes the well-known T4 lysozyme (commonly called T4L) that functions to break the peptidoglycan layer late in the infection cycle, which is required for liberating newly assembled phage progeny. Gene product 5 (gp5) is the tail-associated lysozyme, a component of the phage particle. It forms a spike at the tip of the tail tube and functions to pierce the outer membrane of the Escherichia coli host cell after the phage has attached to the cell surface. Gp5 contains a T4L-like lysozyme domain that locally digests the peptidoglycan layer upon infection. The T4 Spackle protein (encoded by gene 61.3) has been thought to play a role in the inhibition of gp5 lysozyme activity and, as a consequence, in making cells infected by bacteriophage T4 resistant to later infection by T4 and closely related phages. Here we show that (1) gp61.3 is secreted into the periplasm where its N-terminal periplasm-targeting peptide is cleaved off; (2) gp61.3 forms a 1:1 complex with the lysozyme domain of gp5 (gp5Lys); (3) gp61.3 selectively inhibits the activity of gp5, but not that of T4L; (4) overexpression of gp5 causes cell lysis. We also report a crystal structure of the gp61.3-gp5Lys complex that demonstrates that unlike other known lysozyme inhibitors, gp61.3 does not interact with the active site cleft. Instead, it forms a “wall” that blocks access of an extended polysaccharide substrate to the cleft and, possibly, locks the enzyme in an “open-jaw”-like conformation making catalysis impossible.

scholarly journals THE FINE STRUCTURE AND FUNCTION OF THE TENTACLE IN TOKOPHRYA INFUSIONUM

1965 ◽  
Vol 25 (3) ◽  
pp. 459-477 ◽  
Author(s):  
Maria A. Rudzinska
Keyword(s):  
Electron Microscope Study ◽  
Structure And Function ◽  
The Body ◽  
Feeding Apparatus ◽  
Dense Bodies ◽  
Structural Details ◽  
Flow Through ◽  
Feeding Process ◽  
Fine Structure And Function ◽  
And Function

The feeding apparatus of Suctoria consists of long, thin, stiff tubes called tentacles. When a swimming prey attaches to the tip of the tentacle a number of events follow in rapid succession. The tentacle broadens, a stream of tiny granules starts to move upward at its periphery to the tip, the prey becomes immobilized and shortly thereafter the cytoplasm of the still living prey begins to flow through the center of the tentacle to the body of the predator. An electron microscope study of the tentacle in Tokophrya infusionum, a protozoan of the subclass Suctoria, has disclosed a number of structural details which help to clarify some of the mechanisms involved in this unusual way of feeding. Each tentacle is composed of two concentric tubes. The lumen of the inner tube is surrounded by 49 tubular fibrils most probably of contractile nature. In the inner tube the cytoplasm of the prey is present during feeding, and in the outer tube are small dense bodies. It was found that the dense bodies originate in the cytoplasm of Tokophrya. They have an elongate, missile-like appearance, pointed at one end, rounded at the other, and are composed of several distinct segments. At the tip of the tentacle they penetrate the plasma membrane, with their pointed ends sticking out. It is assumed that the missile-like bodies play a major role in the feeding process. Their composite structure suggests that they might contain a number of enzymes which most probably are responsible for the various events preceding the actual food intake.

scholarly journals Structure and function of the complex formed by the tuberculosis virulence factors CFP-10 and ESAT-6

2005 ◽  
Vol 24 (14) ◽  
pp. 2491-2498 ◽  
Author(s):  
Philip S Renshaw ◽  
Kirsty L Lightbody ◽  
Vaclav Veverka ◽  
Fred W Muskett ◽  
Geoff Kelly ◽  
...  
Keyword(s):  
Virulence Factors ◽  
Structure And Function ◽  
And Function
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