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HilD 3'UTR Regulatory Element
The 3′ UTR of mRNA ''hilD'', a master regulator of ''Salmonella'' pathogenicity island 1 (SPI-1), is a prokaryotic example of functional 3'UTR. The 3'UTR is a target for ''hilD'' mRNA degradation by the degradosome and it may play a role in ''hilD'' and SPI-1 expression by serving as a target for the Hfq The Hfq protein (also known as HF-I protein) encoded by the ''hfq'' gene was discovered in 1968 as an ''Escherichia coli'' host factor that was essential for replication of the bacteriophage Qβ. It is now clear that Hfq is an abundant bacterial RN ... RNA chaperone. Under non-invasive conditions it is necessary to keep low levels of SPI-1 expression. It plays a role in S. Typhimurium virulence as a regulatory motif. References RNA Non-coding RNA {{molecular-cell-biology-stub ... [...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] |
Sequence Conservation
In evolutionary biology, conserved sequences are identical or similar sequences in nucleic acids ( DNA and RNA) or proteins across species ( orthologous sequences), or within a genome ( paralogous sequences), or between donor and receptor taxa ( xenologous sequences). Conservation indicates that a sequence has been maintained by natural selection. A highly conserved sequence is one that has remained relatively unchanged far back up the phylogenetic tree, and hence far back in geological time. Examples of highly conserved sequences include the RNA components of ribosomes present in all domains of life, the homeobox sequences widespread amongst Eukaryotes, and the tmRNA in Bacteria. The study of sequence conservation overlaps with the fields of genomics, proteomics, evolutionary biology, phylogenetics, bioinformatics and mathematics. History The discovery of the role of DNA in heredity, and observations by Frederick Sanger of variation between animal insulins in 1949, promp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among the first life forms to appear on Earth, and are present in most of its habitats. Bacteria inhabit soil, water, acidic hot springs, radioactive waste, and the deep biosphere of Earth's crust. Bacteria are vital in many stages of the nutrient cycle by recycling nutrients such as the fixation of nitrogen from the atmosphere. The nutrient cycle includes the decomposition of dead bodies; bacteria are responsible for the putrefaction stage in this process. In the biological communities surrounding hydrothermal vents and cold seeps, extremophile bacteria provide the nutrients needed to sustain life by converting dissolved compounds, such as hydrogen sulphide and methane, to energy. Bacteria also live in symbiotic and parasitic relationsh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pathogenicity Island
Pathogenicity islands (PAIs), as termed in 1990, are a distinct class of genomic islands acquired by microorganisms through horizontal gene transfer. Pathogenicity islands are found in both animal and plant pathogens. Additionally, PAIs are found in both gram-positive and gram-negative bacteria. They are transferred through horizontal gene transfer events such as transfer by a plasmid, phage, or conjugative transposon. Therefore, PAIs contribute to microorganisms' ability to evolve. One species of bacteria may have more than one PAI. For example, ''Salmonella'' has at least five. An analogous genomic structure in rhizobia is termed a '' symbiosis island''. Properties Pathogenicity islands (PAIs) are gene clusters incorporated in the genome, chromosomally or extrachromosomally, of pathogenic organisms, but are usually absent from those nonpathogenic organisms of the same or closely related species. They may be located on a bacterial chromosome or may be transferred within a plas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Three Prime Untranslated Region
In molecular genetics, the three prime untranslated region (3′-UTR) is the section of messenger RNA (mRNA) that immediately follows the translation termination codon. The 3′-UTR often contains regulatory regions that post-transcriptionally influence gene expression. During gene expression, an mRNA molecule is transcribed from the DNA sequence and is later translated into a protein. Several regions of the mRNA molecule are not translated into a protein including the 5' cap, 5' untranslated region, 3′ untranslated region and poly(A) tail. Regulatory regions within the 3′-untranslated region can influence polyadenylation, translation efficiency, localization, and stability of the mRNA. The 3′-UTR contains both binding sites for regulatory proteins as well as microRNAs (miRNAs). By binding to specific sites within the 3′-UTR, miRNAs can decrease gene expression of various mRNAs by either inhibiting translation or directly causing degradation of the transcript. The 3â ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Degradosome
The degradosome is a multiprotein complex present in most bacteria that is involved in the processing of ribosomal RNA and the degradation of messenger RNA and is regulated by Non-coding RNA. It contains the proteins RNA helicase B, RNase E and Polynucleotide phosphorylase. The store of cellular RNA in the cells is constantly fluctuating. For example, in ''Escherichia coli'', Messenger RNA's life expectancy is between 2 and 25 minutes, in other bacteria it might last longer. Even in resting cells, RNA is degraded in a steady state, and the nucleotide products of this process are later reused for fresh rounds of nucleic acid synthesis. RNA turnover is very important for gene regulation and quality control. All organisms have various tools for RNA degradation, for instance ribonucleases, helicases, 3'-end nucleotidyltransferases (which add tails to transcripts), 5'-end capping and decapping enzymes and assorted RNA-binding proteins that help to model RNA for presentation as subs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hfq Protein
The Hfq protein (also known as HF-I protein) encoded by the ''hfq'' gene was discovered in 1968 as an ''Escherichia coli'' host factor that was essential for replication of the bacteriophage Qβ. It is now clear that Hfq is an abundant bacterial RNA binding protein which has many important physiological roles that are usually mediated by interacting with Hfq binding sRNA. In ''E. coli'', Hfq mutants show multiple stress response related phenotypes. The Hfq protein is now known to regulate the translation of two major stress transcription factors ( σS (RpoS) and σE (RpoE) ) in Enterobacteria. It also regulates sRNA in ''Vibrio cholerae'', a specific example being MicX sRNA. In ''Salmonella typhimurium'', Hfq has been shown to be an essential virulence factor as its deletion attenuates the ability of ''S.typhimurium'' to invade epithelial cells, secrete virulence factors or survive in cultured macrophages. In ''Salmonella'', Hfq deletion mutants are also non motile and exhibit chro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
