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Potyvirus
''Potyvirus'' is a genus of positive-strand RNA viruses in the family ''Potyviridae''. Plants serve as natural hosts. The genus is named after member virus ''potato virus Y''. Potyviruses account for about thirty percent of the currently known plant viruses. Like begomoviruses, members of this genus may cause significant losses in agricultural, pastoral, horticultural, and ornamental crops. More than 200 species of aphids spread potyviruses, and most are from the subfamily ''Aphidinae'' (genera ''Macrosiphum'' and ''Myzus''). The genus contains 190 species. Virology Structure The virion is non-enveloped with a flexuous and filamentous nucleocapsid, 680 to 900 nanometers (nm) long and is 11–20 nm in diameter. The nucleocapsid contains around 2000 copies of the capsid protein. The symmetry of the nucleocapsid is helical with a pitch of 3.4 nm. Genome The genome is a linear, positive-sense, single-stranded RNA ranging in size from 9,000–12,000 nucleotide bas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potato Virus Y
Potato virus Y (PVY) is a plant pathogenic virus of the family '' Potyviridae'', and one of the most important plant viruses affecting potato production. PVY infection of potato plants results in a variety of symptoms depending on the viral strain. The mildest of these symptoms is production loss, but the most detrimental is 'potato tuber necrotic ringspot disease' (PTNRD). Necrotic ringspots render potatoes unmarketable and can therefore result in a significant loss of income. PVY is transmissible by aphid vectors but may also remain dormant in seed potatoes. This means that using the same line of potato for production of seed potatoes for several consecutive generations will lead to a progressive increase in viral load and subsequent loss of crop. An increase in potato plant infection with viruses over the past few years has led to considerable losses to the South African potato industry. The increased rate of infection may be attributed to several factors. These include a mar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potyviridae
''Potyviridae'' is a family of positive-strand RNA viruses that encompasses more than 30% of known plant viruses, many of which are of great agricultural significance. The family has 12 genera and 235 species, three of which are unassigned to a genus. Structure Potyvirid virions are nonenveloped, flexuous filamentous, rod-shaped particles. The diameter is around 12–15 nm, with a length of 200–300 nm. Genome Genomes are linear and usually nonsegmented, around 8–12kb in length, consisting of positive-sense RNA, which is surrounded by a protein coat made up of a single viral encoded protein called a capsid. All induce the formation of virus inclusion bodies called cylindrical inclusions (‘pinwheels’) in their hosts. These consist of a single protein (about 70 kDa) made in their hosts from a single viral genome product. Member viruses encode large polypeptides that are cleaved into mature proteins. In 5'–3' order these proteins are * P1 (a serine prot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helper-component Proteinase
Helper-component proteinase (, ''HC-Pro'') is an enzyme. This enzyme catalyses the following chemical reaction : Hydrolyses a Gly-Gly bond at its own C-terminus, commonly in the sequence -Tyr-Xaa-Val-Gly-Gly, in the processing of the potyviral polyprotein This enzyme is present in plant RNA viruses of the '' Potyviridae'' family. HC-Pro is encoded by all potyviruses, but is absent in some members of the ''Ipomovirus ''Ipomovirus'' is a genus of positive-strand RNA viruses in the family '' Potyviridae''. Member viruses infect plants and are transmitted by whiteflies ('' Bemisia tabaci''). The name of the genus is derived from '' Ipomoea'' – the generic na ...'' genus. HC-Pro is involved in virus transmission, virus polyprotein processing, and suppression of RNA silencing, an antiviral mechanism of plants. References External links * {{Portal bar, Biology, border=no EC 3.4.22 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Open Reading Frame
In molecular biology, open reading frames (ORFs) are defined as spans of DNA sequence between the start and stop codons. Usually, this is considered within a studied region of a Prokaryote, prokaryotic DNA sequence, where only one of the #Six-frame translation, six possible reading frames will be "open" (the "reading", however, refers to the RNA produced by Transcription (biology), transcription of the DNA and its subsequent interaction with the ribosome in Translation (biology), translation). Such an ORF may contain a start codon (usually AUG in terms of RNA) and by definition cannot extend beyond a stop codon (usually UAA, UAG or UGA in RNA). That start codon (not necessarily the first) indicates where translation may start. The transcription terminator, transcription termination site is located after the ORF, beyond the Translation (biology), translation stop codon. If transcription were to cease before the stop codon, an incomplete protein would be made during translation. In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aphidinae
Aphidinae is an aphid subfamily in the family Aphididae. Many species of aphids spread potyviruses and most are from the subfamily Aphidinae (genera ''Macrosiphum'' and ''Myzus''). Most have alternative hosts, the primary host plant is usually a tree, and the secondary one is herbaceous. See also * List of Aphidinae genera These 283 genera belong to Aphidinae, a subfamily of aphids in the family Aphididae. There are at least 3,200 described species in Aphidinae. Aphidinae genera * '' Abstrusomyzus'' Jensen & Stoetzel, 1999 * '' Acaudella'' Nevsky, 1929 * '' Acaudi ... References External links * * Hemiptera subfamilies {{Aphididae-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Positive-strand RNA Virus
Positive-strand RNA viruses (+ssRNA viruses) are a group of related viruses that have positive-sense, single-stranded genomes made of ribonucleic acid. The positive-sense genome can act as messenger RNA (mRNA) and can be directly translated into viral proteins by the host cell's ribosomes. Positive-strand RNA viruses encode an RNA-dependent RNA polymerase (RdRp) which is used during replication of the genome to synthesize a negative-sense antigenome that is then used as a template to create a new positive-sense viral genome. Positive-strand RNA viruses are divided between the phyla '' Kitrinoviricota'', '' Lenarviricota'', and '' Pisuviricota'' (specifically classes '' Pisoniviricetes'' and '' Stelpavirictes'') all of which are in the kingdom '' Orthornavirae'' and realm ''Riboviria''. They are monophyletic and descended from a common RNA virus ancestor. In the Baltimore classification system, +ssRNA viruses belong to Group IV. Positive-sense RNA viruses include patho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proteolysis
Proteolysis is the breakdown of proteins into smaller polypeptides or amino acids. Uncatalysed, the hydrolysis of peptide bonds is extremely slow, taking hundreds of years. Proteolysis is typically catalysed by cellular enzymes called proteases, but may also occur by intra-molecular digestion. Proteolysis in organisms serves many purposes; for example, digestive enzymes break down proteins in food to provide amino acids for the organism, while proteolytic processing of a polypeptide chain after its synthesis may be necessary for the production of an active protein. It is also important in the regulation of some physiological and cellular processes including apoptosis, as well as preventing the accumulation of unwanted or misfolded proteins in cells. Consequently, abnormality in the regulation of proteolysis can cause disease. Proteolysis can also be used as an analytical tool for studying proteins in the laboratory, and it may also be used in industry, for example in food pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ribosomal Frameshift
Ribosomal frameshifting, also known as translational frameshifting or translational recoding, is a biological phenomenon that occurs during translation that results in the production of multiple, unique proteins from a single mRNA. The process can be programmed by the nucleotide sequence of the mRNA and is sometimes affected by the secondary, 3-dimensional mRNA structure. It has been described mainly in viruses (especially retroviruses), retrotransposons and bacterial insertion elements, and also in some cellular genes. Process overview Proteins are translated by reading tri-nucleotides on the mRNA strand, also known as codons, from one end of the mRNA to the other (from the 5' to the 3' end) starting with the amino acid methionine as the start (initiation) codon AUG. Each codon is translated into a single amino acid. The code itself is considered degenerate, meaning that a particular amino acid can be specified by more than one codons. However, a shift of any number of nucleoti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dalton (unit)
The dalton or unified atomic mass unit (symbols: Da or u) is a non-SI unit of mass widely used in physics and chemistry. It is defined as of the mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state and at rest. The atomic mass constant, denoted ''m''u, is defined identically, giving . This unit is commonly used in physics and chemistry to express the mass of atomic-scale objects, such as atoms, molecules, and elementary particles, both for discrete instances and multiple types of ensemble averages. For example, an atom of helium-4 has a mass of . This is an intrinsic property of the isotope and all helium-4 atoms have the same mass. Acetylsalicylic acid (aspirin), , has an average mass of approximately . However, there are no acetylsalicylic acid molecules with this mass. The two most common masses of individual acetylsalicylic acid molecules are , having the most common isotopes, and , in which one carbon is carbon-13. The molecular ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plum Pox Virus
A plum is a fruit of some species in ''Prunus'' subg. ''Prunus''''.'' Dried plums are called prunes. History Plums may have been one of the first fruits domesticated by humans. Three of the most abundantly cultivated species are not found in the wild, only around human settlements: ''Prunus domestica'' has been traced to East European and Caucasian mountains, while ''Prunus salicina'' and ''Prunus simonii'' originated in China. Plum remains have been found in Neolithic age archaeological sites along with olives, grapes and figs. According to Ken Albala, plums originated in Iran. They were brought to Britain from Asia. An article on plum tree cultivation in Andalusia (southern Spain) appears in Ibn al-'Awwam's 12th-century agricultural work, ''Book on Agriculture''. Etymology and names The name plum derived from Old English ''plume'' "plum, plum tree", borrowed from Germanic or Middle Dutch, derived from Latin ' and ultimately from Ancient Greek ''proumnon'', itself believ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Serine
Serine (symbol Ser or S) is an α-amino acid that is used in the biosynthesis of proteins. It contains an α- amino group (which is in the protonated − form under biological conditions), a carboxyl group (which is in the deprotonated − form under biological conditions), and a side chain consisting of a hydroxymethyl group, classifying it as a polar amino acid. It can be synthesized in the human body under normal physiological circumstances, making it a nonessential amino acid. It is encoded by the codons UCU, UCC, UCA, UCG, AGU and AGC. Occurrence This compound is one of the naturally occurring proteinogenic amino acids. Only the L- stereoisomer appears naturally in proteins. It is not essential to the human diet, since it is synthesized in the body from other metabolites, including glycine. Serine was first obtained from silk protein, a particularly rich source, in 1865 by Emil Cramer. Its name is derived from the Latin for silk, ''sericum''. Serine's structure w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protease
A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalyzes (increases reaction rate or "speeds up") proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the formation of new protein products. They do this by cleaving the peptide bonds within proteins by hydrolysis, a reaction where water breaks bonds. Proteases are involved in many biological functions, including digestion of ingested proteins, protein catabolism (breakdown of old proteins), and cell signaling. In the absence of functional accelerants, proteolysis would be very slow, taking hundreds of years. Proteases can be found in all forms of life and viruses. They have independently evolved multiple times, and different classes of protease can perform the same reaction by completely different catalytic mechanisms. Hierarchy of proteases Based on catalytic residue Proteases can be classified into seven broad groups: * Serine prot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
