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PreQ1-III Riboswitch
PreQ1-III riboswitches are a class of riboswitches that bind pre-queuosine1 (PreQ1), a precursor to the modified nucleoside queuosine. PreQ1-III riboswitches are the third class of riboswitches to be discovered that sense this ligand, and are structurally distinct from preQ1-I and preQ1-II riboswitches. Most sequenced examples of preQ1-III riboswitches are obtained from uncultivated metagenome samples, but the few examples in cultivated organisms are present in strains that are known to or suspected to be ''Faecalibacterium prausnitzii'', a species of Gram-positive Clostridia The Clostridia are a highly polyphyletic class of Bacillota, including '' Clostridium'' and other similar genera. They are distinguished from the Bacilli by lacking aerobic respiration. They are obligate anaerobes and oxygen is toxic to them .... Known examples of preQ1-III riboswitches are found upstream of ''queT'' genes, which are expected to encode transporters of a queuosine derivative. The othe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Riboswitch
In molecular biology, a riboswitch is a regulatory segment of a messenger RNA molecule that binds a small molecule, resulting in a change in Translation (biology), production of the proteins encoded by the mRNA. Thus, an mRNA that contains a riboswitch is directly involved in regulating its own activity, in response to the concentrations of its Effector (biology), effector molecule. The discovery that modern organisms use RNA to bind small molecules, and discriminate against closely related analogs, expanded the known natural capabilities of RNA beyond its ability to code for proteins, ribozyme, catalyze reactions, or to bind other RNA or protein macromolecules. The original definition of the term "riboswitch" specified that they directly sense small-molecule metabolite concentrations. Although this definition remains in common use, some biologists have used a broader definition that includes other cis-regulatory element, cis-regulatory RNAs. However, this article will discuss o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Queuosine
Queuosine is a modified nucleoside that is present in certain tRNAs in bacteria and eukaryotes. It contains the nucleobase queuine. Originally identified in ''E. coli'', queuosine was found to occupy the first anticodon position of tRNAs for histidine, aspartic acid, asparagine and tyrosine. The first anticodon position pairs with the third "wobble" position in codons, and queuosine improves accuracy of translation compared to guanosine. Synthesis of queuosine begins with GTP. In bacteria, three structurally unrelated classes of riboswitch are known to regulate gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...s that are involved in the synthesis or transport of pre-queuosine1, a precursor to queuosine: PreQ1-I riboswitches, PreQ1-II riboswitches and PreQ1-III riboswitc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PreQ1 Riboswitch
The PreQ1-I riboswitch is a cis-acting element identified in bacteria which regulates expression of genes involved in biosynthesis of the nucleoside queuosine (Q) from Guanosine triphosphate, GTP. PreQ1 (pre-queuosine1) is an intermediate in the queuosine pathway, and preQ1 riboswitch, as a type of riboswitch, is an RNA element that binds preQ1. The preQ1 riboswitch is distinguished by its unusually small aptamer, compared to other riboswitches. Its atomic-resolution three-dimensional structure has been determined, with thPDB ID 2L1V PreQ1 classification Three subcategories of the PreQ1 riboswitch exist: preQ1-I, preQ1-II, and preQ1-III. PreQ1-I has a distinctly small aptamer, ranging from 25 to 45 nucleotides long, compared to the structures of PreQ1-II riboswitch, PreQ1-II riboswitch and PreQ1-III riboswitch, preQ1-III riboswitch. PreQ1-II riboswitch, only found in ''Lactobacillales'', has a larger and more complex consensus sequence and structure than preQ1-I riboswitch, with an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PreQ1-II Riboswitch
PreQ1-II riboswitches form a class of riboswitches that specifically bind pre-queuosine1 (PreQ1), a precursor of the modified nucleoside queuosine. They are found in certain species of ''Streptococcus'' and ''Lactococcus'', and were originally identified as a conserved RNA secondary structure called the "COG4708 motif". All known members of this riboswitch class appear to control members of COG4708 genes. These genes are predicted to encode membrane-bound proteins and have been proposed to be a transporter of preQ1, or a related metabolite, based on their association with preQ1-binding riboswitches. PreQ1-II riboswitches have no apparent similarities in sequence or structure to preQ1-I riboswitches, a previously discovered class of preQ1-binding riboswitches. PreQ1 thus joins S-adenosylmethionine ''S''-Adenosyl methionine (SAM), also known under the commercial names of SAMe, SAM-e, or AdoMet, is a common cosubstrate involved in methyl group transfers, transsulfuration, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metagenome
Metagenomics is the study of all genetic material from all organisms in a particular environment, providing insights into their composition, diversity, and functional potential. Metagenomics has allowed researchers to profile the microbial composition of environmental and clinical samples without the need for time-consuming culture of individual species. Metagenomics has transformed microbial ecology and evolutionary biology by uncovering previously hidden biodiversity and metabolic capabilities. As the cost of DNA sequencing continues to decline, metagenomic studies now routinely profile hundreds to thousands of samples, enabling large-scale exploration of microbial communities and their roles in health and global ecosystems. Metagenomic studies most commonly employ shotgun sequencing though long-read sequencing is being increasingly utilised as technologies advance. The field is also referred to as environmental genomics, ecogenomics, community genomics, or microbiomics ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Faecalibacterium Prausnitzii
''Faecalibacterium'' is a genus of bacteria. The genus contains several species including ''Faecalibacterium prausnitzii'', ''Faecalibacterium butyricigenerans'', ''Faecalibacterium longum'', ''Faecalibacterium duncaniae'', ''Faecalibacterium hattorii'', and ''Faecalibacterium gallinarum''. Its first known species, ''Faecalibacterium prausnitzii'' (renamed as Faecalibacterium ''duncaniae'') is gram-positive, mesophilic, rod-shaped, and anaerobic, and is one of the most abundant and important commensal bacteria of the human gut microbiota. It is non-spore forming and non-motile. These bacteria produce butyrate and other short-chain fatty acids through the fermentation of dietary fiber. The production of butyrate makes them an important member of the gut microbiota, fighting against inflammation. History Formerly assigned to the genus ''Fusobacterium'' in the phylum Fusobacteriota, ''Faecalibacterium prausnitzii'' was re-assigned to its own genus when phylogenetic analysis of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gram-positive
In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. The Gram stain is used by microbiologists to place bacteria into two main categories, gram-positive (+) and gram-negative bacteria, gram-negative (−). Gram-positive bacteria have a thick layer of peptidoglycan within the cell wall, and gram-negative bacteria have a thin layer of peptidoglycan. Gram-positive bacteria retain the crystal violet stain used in the test, resulting in a purple color when observed through an optical microscope. The thick layer of peptidoglycan in the bacterial cell wall retains the Stain (biology), stain after it has been fixed in place by iodine. During the decolorization step, the decolorizer removes crystal violet from all other cells. Conversely, gram-negative bacteria cannot retain the violet stain after the decolorization ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clostridia
The Clostridia are a highly polyphyletic class of Bacillota, including '' Clostridium'' and other similar genera. They are distinguished from the Bacilli by lacking aerobic respiration. They are obligate anaerobes and oxygen is toxic to them. Species of the class Clostridia are often but not always Gram-positive (see '' Halanaerobium'') and have the ability to form spores. Studies show they are not a monophyletic group, and their relationships are not entirely certain. Currently, most are placed in a single order called Clostridiales, but this is not a natural group and is likely to be redefined in the future. Most species of the genus ''Clostridium'' are saprophytic organisms that ferment plant polysaccharides and are found in many places in the environment, most notably the soil. However, the genus does contain some human pathogens (outlined below). The toxins produced by certain members of the genus ''Clostridium'' are among the most dangerous known. Examples are tetan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cis-regulatory RNA Elements
''Cis-acting replication elements (cre)'' bring together the 5′ and 3′ ends during replication of positive-sense single-stranded RNA viruses (for example Picornavirus, Flavivirus, Coronavirus, Togaviruses, Hepatitis C virus) and double-stranded RNA viruses (for example rotavirus and reovirus). ''Cre'' are regions of the viral RNA that act as regulatory signals for essential steps in the virus life cycle. These regions typically fold into loop-like structures and are located in the protein-making part of the genome called the translated region or flanking these regions in parts of the genome called the untranslated region. These folded RNA structures interact with proteins from the virus or host to manage processes like making new viral proteins and replicating the virus’ genetic material. The exact shape and role of these structures vary between different types of viruses. Function of ''cres'' in Viral Replication Positive-Sense RNA Virus Replication The replication ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
