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RTX Toxin
The RTX toxin superfamily is a group of cytolysins and cytotoxins produced by bacteria. There are over 1000 known members with a variety of functions. The RTX family is defined by two common features: characteristic repeats in the toxin protein sequences, and extracellular secretion by the type I secretion systems (T1SS). The name RTX (repeats in toxin) refers to the glycine and aspartate-rich repeats located at the C-terminus of the toxin proteins, which facilitate export by a dedicated T1SS encoded within the ''rtx'' operon. Structure and function RTX proteins range from 40 to over 600 kDa in size and all contain C-terminally located glycine and aspartate-rich repeat sequences of nine amino acids. The repeats contain the common sequence structure , (where X represents any amino acid), but the number of repeats varies within RTX protein family members. These consensus regions function as sites for Ca2+ binding, which facilitate folding of the RTX protein following export via an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytotoxicity
Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are an immune cell or some types of venom, e.g. from the puff adder (''Bitis arietans'') or brown recluse spider (''Loxosceles reclusa''). Cell physiology Treating cells with the cytotoxic compound can result in a variety of cell fates. The cells may undergo necrosis, in which they lose membrane integrity and die rapidly as a result of cell lysis. The cells can stop actively growing and dividing (a decrease in cell viability), or the cells can activate a genetic program of controlled cell death (apoptosis). Cells undergoing necrosis typically exhibit rapid swelling, lose membrane integrity, shut down metabolism, and release their contents into the environment. Cells that undergo rapid necrosis in vitro do not have sufficient time or energy to activate apoptotic machinery and will not express apoptotic markers. Apoptosis is characterized by well defined cytological and molecular events including a change i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clostridial Cytotoxin Family
The Clostridial Cytotoxin (CCT) FamilyTC# 1.C.57 is a member of the RTX-toxin superfamily. There are currently 13 classified members belonging to the CCT family. A representative list of these proteins is available in thTransporter Classification Database Homologues are found in a variety of Gram-positive and Gram-negative bacteria. ''Clostridium difficile'' cytotoxins ''Clostridium difficile'', the causative agent of nosocomial antibiotic-associated diarrhea and pseudomembranous colitis, possesses two main virulence factors: the large clostridial cytotoxins A (TcdATC# 1.C.57.1.2 and B (TcdBTC# 1.C.57.1.1. Action by large clostridial toxins (LCTs) from Clostridium difficile includes four steps: (1) receptor-mediated endocytosis, (2) translocation of a catalytic glucosyltransferase domain across the membrane, (3) release of the enzymatic part by auto-proteolysis, and (4) inactivation of Rho family proteins. Cleavage of toxin B and all other large clostridial cytotoxins, is an au ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Urinary Tract Infection
A urinary tract infection (UTI) is an infection that affects part of the urinary tract. When it affects the lower urinary tract it is known as a bladder infection (cystitis) and when it affects the upper urinary tract it is known as a kidney infection (pyelonephritis). Symptoms from a lower urinary tract infection include pain with urination, frequent urination, and feeling the need to urinate despite having an empty bladder. Symptoms of a kidney infection include fever and flank pain usually in addition to the symptoms of a lower UTI. Rarely the urine may appear bloody. In the very old and the very young, symptoms may be vague or non-specific. The most common cause of infection is ''Escherichia coli'', though other bacteria or fungi may sometimes be the cause. Risk factors include female anatomy, sexual intercourse, diabetes, obesity, and family history. Although sexual intercourse is a risk factor, UTIs are not classified as sexually transmitted infections (STIs). Kidney ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
UPEC
''Escherichia coli'' ( Anglicized to ; commonly abbreviated ''E. coli'') is a gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms (endotherms). Most ''E. coli'' strains are harmless, but pathogenic varieties cause serious food poisoning, septic shock, meningitis, or urinary tract infections in humans. Unlike normal flora ''E. coli'', the pathogenic varieties produce toxins and other virulence factors that enable them to reside in parts of the body normally not inhabited by ''E. coli'', and to damage host cells. These pathogenic traits are encoded by virulence genes carried only by the pathogens. Introduction ''E. coli'' and related bacteria constitute about 0.1% of gut flora, and fecal–oral transmission is the major route through which pathogenic strains of the bacterium cause disease. Cells are able to survive outside the body for only a limited amount of time, which makes them ideal indicator organisms to test envir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virulence Factor
Virulence factors (preferably known as pathogenicity factors or effectors in plant science) are cellular structures, molecules and regulatory systems that enable microbial pathogens (bacteria, viruses, fungi, and protozoa) to achieve the following: * colonization of a niche in the host (this includes movement towards and attachment to host cells) * immunoevasion, evasion of the host's immune response * immunosuppression, inhibition of the host's immune response (this includes leukocidin-mediated cell death) * entry into and exit out of cells (if the pathogen is an intracellular one) * obtain nutrition from the host Specific pathogens possess a wide array of virulence factors. Some are chromosomally encoded and intrinsic to the bacteria (e.g. capsules and endotoxin), whereas others are obtained from mobile genetic elements like plasmids and bacteriophages (e.g. some exotoxins). Virulence factors encoded on mobile genetic elements spread through horizontal gene transfer, and can co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pathogenic Escherichia Coli
''Escherichia coli'' ( Anglicized to ; commonly abbreviated ''E. coli'') is a gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms (endotherms). Most ''E. coli'' strains are harmless, but pathogenic varieties cause serious food poisoning, septic shock, meningitis, or urinary tract infections in humans. Unlike normal flora ''E. coli'', the pathogenic varieties produce toxins and other virulence factors that enable them to reside in parts of the body normally not inhabited by ''E. coli'', and to damage host cells. These pathogenic traits are encoded by virulence genes carried only by the pathogens. Introduction ''E. coli'' and related bacteria constitute about 0.1% of gut flora, and fecal–oral transmission is the major route through which pathogenic strains of the bacterium cause disease. Cells are able to survive outside the body for only a limited amount of time, which makes them ideal indicator organisms to test en ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vibrio Vulnificus
''Vibrio vulnificus'' is a species of Gram-negative, motile, curved rod-shaped (bacillus), pathogenic bacteria of the genus ''Vibrio''. Present in marine environments such as estuaries, brackish ponds, or coastal areas, ''V. vulnificus'' is related to '' ''V. cholerae'''', the causative agent of cholera. At least one strain of ''V. vulnificus'' is bioluminescent. Infection with ''V. vulnificus'' leads to rapidly expanding cellulitis or sepsis. It was first isolated as a source of disease in 1976. Signs and symptoms ''Vibrio vulnificus'' is an extremely virulent bacterium that can cause three types of infections: * Acute gastroenteritis from eating raw or undercooked shellfish: ''V. vulnificus'' causes an infection often incurred after eating seafood, especially raw or undercooked oysters. It does not alter the appearance, taste, or odor of oysters. Symptoms include vomiting, diarrhea, and abdominal pain. * Necrotizing wound infections can occur in injured skin exposed to contam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vibrio
''Vibrio'' is a genus of Gram-negative bacteria, possessing a curved-rod (comma) shape, several species of which can cause foodborne infection, usually associated with eating undercooked seafood. Being highly salt tolerant and unable to survive in fresh water, ''Vibrio'' spp. are commonly found in various salt water environments. ''Vibrio'' spp. are facultative anaerobes that test positive for oxidase and do not form spores. All members of the genus are motile. They are able to have polar or lateral flagellum with or without sheaths. ''Vibrio'' species typically possess two chromosomes, which is unusual for bacteria. Each chromosome has a distinct and independent origin of replication, and are conserved together over time in the genus. Recent phylogenies have been constructed based on a suite of genes (multilocus sequence analysis). O. F. Müller (1773, 1786) described eight species of the genus ''Vibrio'' (included in Infusoria), three of which were spirilliforms. Some of the o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pasteurellaceae
The Pasteurellaceae comprise a large family of Gram-negative bacteria. Most members live as commensals on mucosal surfaces of birds and mammals, especially in the upper respiratory tract. Pasteurellaceae are typically rod-shaped, and are a notable group of facultative anaerobes. Their biochemical characteristics can be distinguished from the related Enterobacteriaceae by the presence of oxidase, and from most other similar bacteria by the absence of flagella. Bacteria in the family Pasteurellaceae have been classified into a number of genera based on metabolic properties, but these classifications are not generally accurate reflections of the evolutionary relationships between different species. ''Haemophilus influenzae'' was the first organism to have its genome sequenced and has been studied intensively by genetic and molecular methodologies. The genus ''Haemophilus'' is a notorious human pathogen associated with bacteremia, pneumonia, meningitis and chancroid. Other pathogenic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bordetella Pertussis
''Bordetella pertussis'' is a Gram-negative, aerobic, pathogenic, encapsulated coccobacillus of the genus ''Bordetella'', and the causative agent of pertussis or whooping cough. Like '' B. bronchiseptica'', ''B. pertussis'' is motile and expresses a flagellum-like structure. Its virulence factors include pertussis toxin, adenylate cyclase toxin, filamentous hæmagglutinin, pertactin, fimbria, and tracheal cytotoxin. The bacterium is spread by airborne droplets; its incubation period is 7–10 days on average (range 6–20 days). Humans are the only known reservoir for ''B. pertussis''. The complete ''B. pertussis'' genome of 4,086,186 base pairs was published in 2003. Compared to its closest relative ''B. bronchiseptica'', the genome size is greatly reduced. This is mainly due to the adaptation to one host species (human) and the loss of capability of survival outside of a host body. History The disease pertussis was first described by French physician Guillaume de Baillo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apoptosis
Apoptosis (from grc, ἀπόπτωσις, apóptōsis, 'falling off') is a form of programmed cell death that occurs in multicellular organisms. Biochemical events lead to characteristic cell changes (morphology) and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, DNA fragmentation, and mRNA decay. The average adult human loses between 50 and 70 billion cells each day due to apoptosis. For an average human child between eight and fourteen years old, approximately twenty to thirty billion cells die per day. In contrast to necrosis, which is a form of traumatic cell death that results from acute cellular injury, apoptosis is a highly regulated and controlled process that confers advantages during an organism's life cycle. For example, the separation of fingers and toes in a developing human embryo occurs because cells between the digits undergo apoptosis. Unlike necrosis, apoptosis produces cell fragments called apoptotic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neutrophil Granulocyte
Neutrophils (also known as neutrocytes or heterophils) are the most abundant type of granulocytes and make up 40% to 70% of all white blood cells in humans. They form an essential part of the innate immune system, with their functions varying in different animals. They are formed from stem cells in the bone marrow and differentiated into subpopulations of neutrophil-killers and neutrophil-cagers. They are short-lived and highly mobile, as they can enter parts of tissue where other cells/molecules cannot. Neutrophils may be subdivided into segmented neutrophils and banded neutrophils (or bands). They form part of the polymorphonuclear cells family (PMNs) together with basophils and eosinophils. The name ''neutrophil'' derives from staining characteristics on hematoxylin and eosin ( H&E) histological or cytological preparations. Whereas basophilic white blood cells stain dark blue and eosinophilic white blood cells stain bright red, neutrophils stain a neutral pink. Normal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
