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Corynebacteriophage
A corynebacteriophage (or just corynephage) is a DNA-containing bacteriophage specific for bacteria of genus ''Corynebacterium'' as its host.NCBICorynephages(list) ''Corynebacterium diphtheriae virus''NCBICorynebacterium diphtheriae virus/phage(species) strain Corynebacterium diphtheriae phage (aka Corynephage βNCBICorynephage beta(species) or just β-phage) introduces toxigenicity into strains of ''Corynebacterium diphtheriae'' as it encodes diphtheria toxin, from L. P. Johnson, M. A. Tomai, P. M. Schlievert [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diphtheria Toxin
Diphtheria toxin is an exotoxin secreted by '' Corynebacterium diphtheriae'', the pathogenic bacterium that causes diphtheria. The toxin gene is encoded by a prophageA prophage is a virus that has inserted itself into the genome of the host bacterium. called corynephage β. The toxin causes the disease in humans by gaining entry into the cell cytoplasm and inhibiting protein synthesis. Structure Diphtheria toxin is a single polypeptide chain of 535 amino acids consisting of two subunits linked by disulfide bridges, known as an A-B toxin. Binding to the cell surface of the B subunit (the less stable of the two subunits) allows the A subunit (the more stable part of the protein) to penetrate the host cell. The crystal structure of the diphtheria toxin homodimer has been determined to 2.5 Ångstrom resolution. The structure reveals a Y-shaped molecule consisting of three domains. Fragment A contains the catalytic C domain, and fragment B consists of the T and R domains: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Corynebacterium
''Corynebacterium'' () is a genus of Gram-positive bacteria and most are aerobe, aerobic. They are bacillus (shape), bacilli (rod-shaped), and in some phases of life they are, more specifically, club (weapon), club-shaped, which inspired the genus name (''coryneform'' means "club-shaped"). They are widely distributed in nature in the microbiota of animals (including the human microbiota) and are mostly innocuous, most commonly existing in commensalism, commensal relationships with their hosts. Some, such as ''Corynebacterium glutamicum, C. glutamicum'', are commercially useful. Others can cause human disease, including, most notably, diphtheria, which is caused by ''Corynebacterium diphtheriae, C. diphtheriae''. As with various species of amicrobiota (including their relatives in the genera ''Arcanobacterium'' and ''Trueperella''), they usually are not pathogenic, but can occasionally opportunistic infection, opportunistically capitalize on atypical access to tissue (biology), ti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bacteriophage
A bacteriophage (), also known informally as a ''phage'' (), is a duplodnaviria virus that infects and replicates within bacteria and archaea. The term was derived from "bacteria" and the Greek φαγεῖν ('), meaning "to devour". Bacteriophages are composed of proteins that encapsulate a DNA or RNA genome, and may have structures that are either simple or elaborate. Their genomes may encode as few as four genes (e.g. MS2) and as many as hundreds of genes. Phages replicate within the bacterium following the injection of their genome into its cytoplasm. Bacteriophages are among the most common and diverse entities in the biosphere. Bacteriophages are ubiquitous viruses, found wherever bacteria exist. It is estimated there are more than 1031 bacteriophages on the planet, more than every other organism on Earth, including bacteria, combined. Viruses are the most abundant biological entity in the water column of the world's oceans, and the second largest component of biom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Corynebacterium Diphtheriae
''Corynebacterium diphtheriae'' is the pathogenic bacterium that causes diphtheria. It is also known as the Klebs–Löffler bacillus, because it was discovered in 1884 by German bacteriologists Edwin Klebs (1834–1912) and Friedrich Löffler (1852–1915). The bacteria are usually harmless unless they are infected by a bacteriophage that carries a gene that gives rise to a toxin. This toxin causes the disease. Diphtheria is caused by the adhesion and infiltration of the bacteria into the mucosal layers of the body, primarily affecting the respiratory tract and the subsequent release of an endotoxin. The toxin has a localized effect on skin lesions, as well as a metastatic, proteolytic effects on other organ systems in severe infections. Originally a major cause of childhood mortality, diphtheria has been almost entirely eradicated due to the vigorous administration of the diphtheria vaccination in the 1910s. Diphtheria is no longer transmitted as frequently due to the d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetic Code
The genetic code is the set of rules used by living cells to translate information encoded within genetic material ( DNA or RNA sequences of nucleotide triplets, or codons) into proteins. Translation is accomplished by the ribosome, which links proteinogenic amino acids in an order specified by messenger RNA (mRNA), using transfer RNA (tRNA) molecules to carry amino acids and to read the mRNA three nucleotides at a time. The genetic code is highly similar among all organisms and can be expressed in a simple table with 64 entries. The codons specify which amino acid will be added next during protein biosynthesis. With some exceptions, a three-nucleotide codon in a nucleic acid sequence specifies a single amino acid. The vast majority of genes are encoded with a single scheme (see the RNA codon table). That scheme is often referred to as the canonical or standard genetic code, or simply ''the'' genetic code, though variant codes (such as in mitochondria) exist. History Effor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lambdavirus
''Lambdavirus'' (synonyms ''Lambda-like viruses'', ''Lambda-like phages'', ''Lambda phage group'', ''Lambda phage'') is a genus of viruses in the order ''Caudovirales'', in the family ''Siphoviridae''. Bacteria serve as natural hosts, with transmission achieved through passive diffusion. There are five species in this genus. The genus also includes several unclassified viruses—including the corynephages β and ω, which infect '' Corynebacterium diphtheriae'' and carry the deadly diphtheria toxin.NCBICorynephage beta(species)NCBICorynephage omega(species) Taxonomy The following species are recognized: * ''Enterobacteria virus O276'' * ''Escherichia virus DE3'' * ''Escherichia virus HK629'' * ''Escherichia virus HK630'' * '' Escherichia virus Lambda'' Structure Lambdaviruses are nonenveloped, with a head and tail. The head is about 60 nm in diameter, consisting of 72 capsomers (T=7, levo). Genome All species have been fully sequenced. They range between 42k and 49k nucle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siphoviridae
''Siphoviridae'' is a family of double-stranded DNA viruses in the order ''Caudovirales''. Bacteria and archaea serve as natural hosts. There are 1,166 species in this family, assigned to 366 genera and 22 subfamilies. The characteristic structural features of this family are a nonenveloped head and noncontractile tail. Structure Viruses in ''Siphoviridae'' are non-enveloped, with icosahedral and head-tail geometries (morphotype B1) or a prolate capsid (morphotype B2), and T=7 symmetry. The diameter is around 60 nm. Members of this family are also characterized by their filamentous, cross-banded, noncontractile tails, usually with short terminal and subterminal fibers. Genomes are double stranded and linear, around 50 kb in length, containing about 70 genes. The guanine/cytosine content is usually around 52%. Life cycle Viral replication is cytoplasmic. Entry into the host cell is achieved by adsorption into the host cell. Replication follows the replicative transposition ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
