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Curli
The Curli protein is a type of amyloid fiber produced by certain strains of enterobacteria. They are extracellular fibers located on bacteria such as ''E. coli'' and ''Salmonella'' spp. These fibers serve to promote cell community behavior through biofilm formation in the extracellular matrix. Amyloids are associated with several human neurodegenerative diseases such as Alzheimer's disease, Huntington's disease, Parkinson's disease, and prion diseases. The study of curli may help to understand human diseases thought to arise from improper amyloid fiber formation. The curli pili are generally assembled through the extracellular nucleation precipitation pathway. Gene biosynthesis and regulation A convenient way to identify genes important for curli production is by growing curliated bacteria on plates supplemented with Congo red diazo dye, which causes a red shift. Curli fibers, and thus the curli protein, are coded by two divergently-transcribed operons in ''E. coli:'' the csg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extracellular Nucleation Precipitation Pathway
A Type VIII secretion system is a type of secretion system found within the inner and outer membranes of gram-negative bacteria. This system is also referred to as the curli biogenesis pathway or the extracellular nucleation-precipitation pathway. It is associated with the formation of biofilms and infecting hosts. Curli formation is especially efficient at evading the host's immune system due to the subunits being able to quickly assemble in a single process and not having intermediates. This system is associated with curli-specific genes and utilizes multiple proteins in its process to form curli fibers. These proteins include CsgA CsgB, CsgC, CsgD, CsgE, CsgF, and CsgG. Type VIII secretion system facilitates the assembly and translocation of curli fibers. Curli fibers and their virulence Curli fibers are made through the curli biogenesis system, also known as the type VIII secretion system, and are essentially long, linear structures made from proteins that are secreted to t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amyloid
Amyloids are aggregates of proteins characterised by a fibrillar morphology of typically 7–13 nm in diameter, a β-sheet secondary structure (known as cross-β) and ability to be stained by particular dyes, such as Congo red. In the human body, amyloids have been linked to the development of various diseases. Pathogenic amyloids form when previously healthy proteins lose their normal structure and physiological functions ( misfolding) and form fibrous deposits within and around cells. These protein misfolding and deposition processes disrupt the healthy function of tissues and organs. Such amyloids have been associated with (but not necessarily as the cause of) more than 50 human diseases, known as amyloidosis, and may play a role in some neurodegenerative diseases. Some of these diseases are mainly sporadic and only a few cases are familial. Others are only familial. Some result from medical treatment. Prions are an infectious form of amyloids that can act as a templa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pilus
A pilus (Latin for 'hair'; : pili) is a hair-like cell-surface appendage found on many bacteria and archaea. The terms ''pilus'' and '' fimbria'' (Latin for 'fringe'; plural: ''fimbriae'') can be used interchangeably, although some researchers reserve the term ''pilus'' for the appendage required for bacterial conjugation. All conjugative pili are primarily composed of pilin – fibrous proteins, which are oligomeric. Dozens of these structures can exist on the bacterial and archaeal surface. Some bacteria, viruses or bacteriophages attach to receptors on pili at the start of their reproductive cycle. Pili are antigenic. They are also fragile and constantly replaced, sometimes with pili of different composition, resulting in altered antigenicity. Specific host responses to old pili structures are not effective on the new structure. Recombination between genes of some (but not all) pili code for variable (V) and constant (C) regions of the pili (similar to immunoglobulin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biofilm
A biofilm is a Syntrophy, syntrophic Microbial consortium, community of microorganisms in which cell (biology), cells cell adhesion, stick to each other and often also to a surface. These adherent cells become embedded within a slimy extracellular matrix that is composed of extracellular polymeric substances (EPSs). The cells within the biofilm produce the EPS components, which are typically a polymeric combination of extracellular polysaccharides, proteins, lipids and DNA. Because they have a three-dimensional structure and represent a community lifestyle for microorganisms, they have been metaphorically described as "cities for microbes". Biofilms may form on living (biotic) or non-living (abiotic) surfaces and can be common in natural, industrial, and hospital settings. They may constitute a microbiome or be a portion of it. The microbial cells growing in a biofilm are physiology, physiologically distinct from planktonic cells of the same organism, which, by contrast, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enterobacteria
Enterobacteriaceae is a large family (biology), family of Gram-negative bacteria. It includes over 30 genera and more than 100 species. Its classification above the level of Family (taxonomy), family is still a subject of debate, but one classification places it in the order Enterobacterales of the class Gammaproteobacteria in the phylum Pseudomonadota. In 2016, the description and members of this family were emended based on comparative genomic analyses by Adeolu et al. Enterobacteriaceae includes, along with many harmless Symbiosis, symbionts, many of the more familiar pathogenic bacteria, pathogens, such as ''Salmonella'', ''Escherichia coli'', ''Klebsiella'', and ''Shigella''. Other disease-causing bacteria in this family include ''Enterobacter'' and ''Citrobacter''. Members of the Enterobacteriaceae can be Bacterial taxonomy#Nomenclature, trivially referred to as enterobacteria or "enteric bacteria", as several members live in the intestines of animals. In fact, the etymol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extracellular Matrix
In biology, the extracellular matrix (ECM), also called intercellular matrix (ICM), is a network consisting of extracellular macromolecules and minerals, such as collagen, enzymes, glycoproteins and hydroxyapatite that provide structural and biochemical support to surrounding cells. Because multicellularity evolved independently in different multicellular lineages, the composition of ECM varies between multicellular structures; however, cell adhesion, cell-to-cell communication and differentiation are common functions of the ECM. The animal extracellular matrix includes the interstitial matrix and the basement membrane. Interstitial matrix is present between various animal cells (i.e., in the intercellular spaces). Gels of polysaccharides and fibrous proteins fill the interstitial space and act as a compression buffer against the stress placed on the ECM. Basement membranes are sheet-like depositions of ECM on which various epithelial cells rest. Each type of connective tissue ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pathogen-associated Molecular Pattern
Pathogen-associated molecular patterns (PAMPs) are small molecular motifs conserved within a class of microbes, but not present in the host. They are recognized by toll-like receptors (TLRs) and other pattern recognition receptors (PRRs) in both plants and animals. This allows the innate immune system to recognize pathogens and thus, protect the host from infection. This initiation of the immune response consists of the secretion of inflammatory cytokines and chemokines. PAMPs can initiate the maturation of immune cells, which can travel to the primary lymph node and trigger the adaptive immune system that involves the production of antibodies against specific antigens. Although the term "PAMP" is relatively new, the concept that molecules derived from microbes must be detected by receptors from multicellular organisms has been held for many decades, and references to an "endotoxin receptor" are found in much of the older literature. The recognition of PAMPs by the PRRs triggers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Escherichia Coli
''Escherichia coli'' ( )Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. is a gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus '' Escherichia'' that is commonly found in the lower intestine of warm-blooded organisms. Most ''E. coli'' strains are part of the normal microbiota of the gut, where they constitute about 0.1%, along with other facultative anaerobes. These bacteria are mostly harmless or even beneficial to humans. For example, some strains of ''E. coli'' benefit their hosts by producing vitamin K2 or by preventing the colonization of the intestine by harmful pathogenic bacteria. These mutually beneficial relationships between ''E. coli'' and humans are a type of mutualistic biological relationship—where both the humans and the ''E. coli'' are benefitting each other. ''E. coli'' is expelled into the environment within fecal matter. The bacterium grows massi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salmonella
''Salmonella'' is a genus of bacillus (shape), rod-shaped, (bacillus) Gram-negative bacteria of the family Enterobacteriaceae. The two known species of ''Salmonella'' are ''Salmonella enterica'' and ''Salmonella bongori''. ''S. enterica'' is the type species and is further divided into six subspecies that include over 2,650 serotypes. ''Salmonella'' was named after Daniel Elmer Salmon (1850–1914), an American veterinary surgeon. ''Salmonella'' species are non-Endospore, spore-forming, predominantly motility, motile enterobacteriaceae, enterobacteria with cell diameters between about 0.7 and 1.5 micrometre, μm, lengths from 2 to 5 μm, and peritrichous flagella (all around the cell body, allowing them to move). They are chemotrophs, obtaining their energy from Redox, oxidation and reduction reactions, using organic sources. They are also facultative aerobic organism, facultative anaerobes, capable of generating adenosine triphosphate with oxygen ("aerobically") ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SDS-PAGE
SDS-PAGE (sodium dodecyl sulfate–polyacrylamide gel electrophoresis) is a Discontinuous electrophoresis, discontinuous electrophoretic system developed by Ulrich K. Laemmli which is commonly used as a method to separate proteins with molecular masses between 5 and 250 Kilodalton, kDa. The combined use of sodium dodecyl sulfate (SDS, also known as sodium lauryl sulfate) and polyacrylamide gel eliminates the influence of structure and charge, and proteins are separated by differences in their size. At least up to 2012, the publication describing it was the most frequently cited paper by a single author, and the second most cited overall. Properties SDS-PAGE is an electrophoresis method that allows protein separation by mass. The medium (also referred to as ′matrix′) is a polyacrylamide-based discontinuous gel. The polyacrylamide-gel is typically sandwiched between two glass plates in a slab gel. Although tube gels (in glass cylinders) were used historically, they were rapid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta Sheet
The beta sheet (β-sheet, also β-pleated sheet) is a common motif of the regular protein secondary structure. Beta sheets consist of beta strands (β-strands) connected laterally by at least two or three backbone hydrogen bonds, forming a generally twisted, pleated sheet. A β-strand is a stretch of polypeptide chain typically 3 to 10 amino acids long with backbone in an extended conformation. The supramolecular association of β-sheets has been implicated in the formation of the fibrils and protein aggregates observed in amyloidosis, Alzheimer's disease and other proteinopathies. History The first β-sheet structure was proposed by William Astbury in the 1930s. He proposed the idea of hydrogen bonding between the peptide bonds of parallel or antiparallel extended β-strands. However, Astbury did not have the necessary data on the bond geometry of the amino acids in order to build accurate models, especially since he did not then know that the peptide bond was planar. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
