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Rsa RNA
Rsa RNAs are non-coding RNAs found in the bacterium ''Staphylococcus aureus''. The shared name comes from their discovery, and does not imply homology. Bioinformatics scans identified the 16 Rsa RNA families named RsaA-K and RsaOA-OG. Others, RsaOH-OX, were found thanks to an RNomic approach. Although the RNAs showed varying expression patterns, many of the newly discovered RNAs were shown to be Hfq-independent and most carried a C-rich motif (UCCC). RsaA Represses the translation of the transcriptional regulator MgrA by binding to its mRNA, enhances biofilm formation and decreases bacterial virulence. Other mRNAs: including SsaA-like enzymes involved in peptidoglycan metabolism and the secreted anti-inflammatory FLIPr protein were validated as direct targets of RsaA. RsaE RsaE is found in other members of the genus ''Staphylococcus'' such as ''Staphylococcus epidermidis'' and ''Staphylococcus saprophyticus'' and is the only Rsa RNA to be found outside of this genus, in '' Mac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Non-coding RNA
A non-coding RNA (ncRNA) is a functional RNA molecule that is not translated into a protein. The DNA sequence from which a functional non-coding RNA is transcribed is often called an RNA gene. Abundant and functionally important types of non-coding RNAs include transfer RNAs (tRNAs) and ribosomal RNAs (rRNAs), as well as small RNAs such as microRNAs, siRNAs, piRNAs, snoRNAs, snRNAs, exRNAs, scaRNAs and the long ncRNAs such as Xist and HOTAIR. The number of non-coding RNAs within the human genome is unknown; however, recent transcriptomic and bioinformatic studies suggest that there are thousands of non-coding transcripts. Many of the newly identified ncRNAs have not been validated for their function. There is no consensus in the literature on how much of non-coding transcription is functional. Some researchers have argued that many ncRNAs are non-functional (sometimes referred to as "junk RNA"), spurious transcriptions. Others, however, disagree, arguing instead that many ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antisense RNA
Antisense RNA (asRNA), also referred to as antisense transcript, natural antisense transcript (NAT) or antisense oligonucleotide, is a single stranded RNA that is complementary to a protein coding messenger RNA (mRNA) with which it hybridizes, and thereby blocks its translation into protein. asRNAs (which occur naturally) have been found in both prokaryotes and eukaryotes, and can be classified into short (200 nucleotides) non-coding RNAs (ncRNAs). The primary function of asRNA is regulating gene expression. asRNAs may also be produced synthetically and have found wide spread use as research tools for gene knockdown. They may also have therapeutic applications. Discovery and history in drug development Some of the earliest asRNAs were discovered while investigating functional proteins. An example was micF asRNA. While characterizing the outer membrane porin in ''E.coli'', some of the promoter clones observed were capable of repressing the expression of other membrane porin s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transcriptional Interference
Transcription is the process of copying a segment of DNA into RNA. The segments of DNA transcribed into RNA molecules that can encode proteins are said to produce messenger RNA (mRNA). Other segments of DNA are copied into RNA molecules called non-coding RNAs (ncRNAs). mRNA comprises only 1–3% of total RNA samples. Less than 2% of the human genome can be transcribed into mRNA ( Human genome#Coding vs. noncoding DNA), while at least 80% of mammalian genomic DNA can be actively transcribed (in one or more types of cells), with the majority of this 80% considered to be ncRNA. Both DNA and RNA are nucleic acids, which use base pairs of nucleotides as a complementary language. During transcription, a DNA sequence is read by an RNA polymerase, which produces a complementary, antiparallel RNA strand called a primary transcript. Transcription proceeds in the following general steps: # RNA polymerase, together with one or more general transcription factors, binds to promoter DN ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Osmotic Stress
Osmotic shock or osmotic stress is physiologic dysfunction caused by a sudden change in the solute concentration around a cell, which causes a rapid change in the movement of water across its cell membrane. Under hypertonic conditions - conditions of high concentrations of either salts, substrates or any solute in the supernatant - water is drawn out of the cells through osmosis. This also inhibits the transport of substrates and cofactors into the cell thus “shocking” the cell. Alternatively, under hypotonic conditions - when concentrations of solutes are low - water enters the cell in large amounts, causing it to swell and either burst or undergo apoptosis. All organisms have mechanisms to respond to osmotic shock, with sensors and signal transduction networks providing information to the cell about the osmolarity of its surroundings; these signals activate responses to deal with extreme conditions. Cells that have a cell wall tend to be more resistant to osmotic shock becau ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cold Shock
Cold shock response is a series of neurogenic cardio-respiratory responses caused by sudden immersion in cold water. In cold water immersions, such as by falling through thin ice, cold shock response is perhaps the most common cause of death. Also, the abrupt contact with very cold water may cause involuntary inhalation, which, if underwater, can result in fatal drowning. Death which occurs in such scenarios is complex to investigate and there are several possible causes and phenomena that can take part. The cold water can cause heart attack due to severe vasoconstriction, where the heart has to work harder to pump the same volume of blood throughout the arteries. For people with pre-existing cardiovascular disease, the additional workload can result in myocardial infarction and/or acute heart failure, which ultimately may lead to a cardiac arrest. A vagal response to an extreme stimulus as this one, may, in very rare cases, render ''per se'' a cardiac arrest. Hypothermia and ext ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudoknot
__NOTOC__ A pseudoknot is a nucleic acid secondary structure containing at least two stem-loop structures in which half of one stem is intercalated between the two halves of another stem. The pseudoknot was first recognized in the turnip yellow mosaic virus in 1982. Pseudoknots fold into knot-shaped three-dimensional conformations but are not true topological knots. Prediction and identification The structural configuration of pseudoknots does not lend itself well to bio-computational detection due to its context-sensitivity or "overlapping" nature. The base pairing in pseudoknots is not well nested; that is, base pairs occur that "overlap" one another in sequence position. This makes the presence of pseudoknots in RNA sequences more difficult to predict by the standard method of dynamic programming, which use a recursive scoring system to identify paired stems and consequently, most cannot detect non-nested base pairs. The newer method of stochastic context-free grammars su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secondary Structure
Protein secondary structure is the three dimensional conformational isomerism, form of ''local segments'' of proteins. The two most common Protein structure#Secondary structure, secondary structural elements are alpha helix, alpha helices and beta sheets, though beta turns and omega loops occur as well. Secondary structure elements typically spontaneously form as an intermediate before the protein protein folding, folds into its three dimensional protein tertiary structure, tertiary structure. Secondary structure is formally defined by the pattern of hydrogen bonds between the Amine, amino hydrogen and carboxyl oxygen atoms in the peptide backbone chain, backbone. Secondary structure may alternatively be defined based on the regular pattern of backbone Dihedral angle#Dihedral angles of proteins, dihedral angles in a particular region of the Ramachandran plot regardless of whether it has the correct hydrogen bonds. The concept of secondary structure was first introduced by Kaj Ulrik ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trans-acting
In the field of molecular biology, ''trans''-acting (''trans''-regulatory, ''trans''-regulation), in general, means "acting from a different molecule" (''i.e.'', intermolecular). It may be considered the opposite of ''cis''-acting (''cis''-regulatory, ''cis''-regulation), which, in general, means "acting from the same molecule" (''i.e.'', intramolecular). In the context of transcription regulation, a ''trans''-acting factor is usually a regulatory protein that binds to DNA. The binding of a ''trans''-acting factor to a ''cis''-regulatory element in DNA can cause changes in transcriptional expression levels. microRNAs or other diffusible molecules are also examples of ''trans''-acting factors that can regulate target sequences. The ''trans''-acting gene may be on a different chromosome to the target gene, but the activity is via the intermediary protein or RNA that it encodes. ''Cis''-acting elements, on the other hand, do not code for protein or RNA. Both the ''trans''-acti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antitermination
Antitermination is the prokaryotic cell's aid to fix premature termination factor, termination of RNA synthesis during the Transcription (genetics), transcription of RNA. It occurs when the RNA polymerase ignores the termination signal and continues elongating its transcript until a second signal is reached. Antitermination provides a mechanism whereby one or more genes at the end of an operon can be switched either on or off, depending on the polymerase either recognizing or not recognizing the termination signal. Antitermination is used by some Bacteriophage, phages to regulate progression from one stage of gene expression to the next. The lambda gene N, codes for an antitermination protein (pN) that is necessary to allow RNA polymerase to read through the terminators located at the ends of the immediate early genes. Another antitermination protein, pQ, is required later in phage infection. pN and pQ act on RNA polymerase as it passes specific sites. These sites are located at diff ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PEP Group Translocation
PEP group translocation, also known as the phosphotransferase system or PTS, is a distinct method used by bacteria for sugar uptake where the source of energy is from phosphoenolpyruvate (PEP). It is known to be a multicomponent system that always involves enzymes of the plasma membrane and those in the cytoplasm. The PTS system uses active transport. After the translocation across the membrane, the metabolites transported are modified. The system was discovered by Saul Roseman in 1964. The bacterial phosphoenolpyruvate:sugar phosphotransferase system (PTS) transports and phosphorylates its sugar substrates in a single energy-coupled step. This transport process is dependent on several cytoplasmic phosphoryl transfer proteins - Enzyme I (I), HPr, Enzyme IIA (IIA), and Enzyme IIB (IIB)) as well as the integral membrane sugar permease (IIC).The PTS Enzyme II complexes are derived from independently evolving 4 PTS Enzyme II complex superfamilies, that include the (1) Glucose (Glc),(2) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. Almost all metabolic processes in the cell need enzyme catalysis in order to occur at rates fast enough to sustain life. Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called ''enzymology'' and the field of pseudoenzyme analysis recognizes that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties. Enzymes are known to catalyze more than 5,000 biochemical reaction types. Other biocatalysts are catalytic RNA molecules, called ribozymes. Enzymes' specificity comes from their unique three-dimensional structures. Like all catalysts, enzymes increase the reaction ra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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