Target type: biologicalprocess
The splicing of Group I introns. This occurs by a ribozymic mechanism where the intron sequence forms a distinct 3D structure, characteristic of Group I introns and involved in determining the locations of the splice sites (there do not appear to be consensus splice site sequences) as well as having a role in catalyzing the splicing reactions, though protein factors are also required in vivo. Splicing occurs by a series of two transesterification reactions, generally with exogenous guanosine as the initiating nucleophile. The intron is excised as a linear piece (though it may subsequently circularize). [GOC:krc, PMID:11377794]
Group I introns are self-splicing ribozymes that catalyze their own excision from precursor RNA molecules. This process is a highly conserved mechanism in diverse organisms, including bacteria, archaea, and eukaryotes. The splicing reaction involves a series of steps, beginning with the recognition and binding of the intron to a specific site on the pre-mRNA. This recognition is mediated by base pairing interactions between the intron and the flanking exons. Once bound, the intron undergoes a series of conformational changes that facilitate the catalytic steps of splicing. The splicing reaction proceeds through a two-step mechanism:
1. **First Step:** The 5' splice site is cleaved, and the 5' exon is joined to a free guanosine cofactor, forming a 3'-OH group at the 5' splice site. This step is often called the "first transesterification reaction."
2. **Second Step:** The 3' splice site is cleaved, and the 3' exon is joined to the 5' exon. This step is often called the "second transesterification reaction," and it results in the ligation of the exons and the release of the intron as a linear molecule.
The splicing reaction is catalyzed by the intron itself, with the RNA molecule acting as both a substrate and a catalyst. This self-splicing activity is a remarkable example of RNA catalysis, and it has been instrumental in understanding the origins of life and the evolution of biological systems. Group I introns are often found in genes that encode essential cellular functions, and their splicing is tightly regulated to ensure the proper expression of these genes. The splicing process is influenced by a variety of factors, including the presence of specific proteins and the availability of cofactors.'
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| Protein | Definition | Taxonomy |
|---|---|---|
| 30S ribosomal protein S12 | A small ribosomal subunit protein uS12 that is encoded in the genome of Escherichia coli K-12. [PRO:DNx, UniProtKB:P0A7S3] | Escherichia coli K-12 |
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| chloramphenicol | Amphenicol: Chloramphenicol and its derivatives. | C-nitro compound; carboxamide; diol; organochlorine compound | antibacterial drug; antimicrobial agent; Escherichia coli metabolite; geroprotector; Mycoplasma genitalium metabolite; protein synthesis inhibitor |
| framycetin | framycetin : A tetracyclic antibacterial agent derived from neomycin, being a glycoside ester of neamine and neobiosamine B. Framycetin: A component of NEOMYCIN that is produced by Streptomyces fradiae. On hydrolysis it yields neamine and neobiosamine B. (From Merck Index, 11th ed) | aminoglycoside | allergen; antibacterial drug; Escherichia coli metabolite |
| erythromycin | erythromycin : Any of several wide-spectrum macrolide antibiotics obtained from actinomycete Saccharopolyspora erythraea (formerly known as Streptomyces erythraeus). erythromycin A : An erythromycin that consists of erythronolide A having 2,6-dideoxy-3-C-methyl-3-O-methyl-alpha-L-ribo-hexopyranosyl and 3,4,6-trideoxy-3-(dimethylamino)-beta-D-xylo-hexopyranosyl residues attahced at positions 4 and 6 respectively. Erythromycin: A bacteriostatic antibiotic macrolide produced by Streptomyces erythreus. Erythromycin A is considered its major active component. In sensitive organisms, it inhibits protein synthesis by binding to 50S ribosomal subunits. This binding process inhibits peptidyl transferase activity and interferes with translocation of amino acids during translation and assembly of proteins. | cyclic ketone; erythromycin | |
| neamine | neamine : 2-Deoxy-D-streptamine glycosylated at the 4-oxygen with a 6-amino-alpha-D-glucosaminyl group. neamine: fragment of NEOMYCIN B; structure in first source | 2,6-dideoxy-alpha-D-glucoside; aminoglycoside | antibacterial agent |
| florfenicol | florfenicol : A carboxamide that is the N-dichloroacetyl derivative of (1R,2S)-2-amino-3-fluoro-1-[4-(methanesulfonyl)phenyl]propan-1-ol. A synthetic veterinary antibiotic that is used for treatment of bovine respiratory disease and foot rot; also used in aquaculture. florfenicol: structure given in first source | organochlorine compound; organofluorine compound; secondary alcohol; secondary carboxamide; sulfone | antimicrobial agent |
| antibiotic g 418 | antibiotic G 418: from Micromonospora rhodorangea | ||
| paromomycin | paromomycin : An amino cyclitol glycoside that is the 1-O-(2-amino-2-deoxy-alpha-D-glucopyranoside) and the 3-O-(2,6-diamino-2,6-dideoxy-beta-L-idopyranosyl)-beta-D-ribofuranoside of 4,6-diamino-2,3-dihydroxycyclohexane (the 1R,2R,3S,4R,6S diastereoisomer). It is obtained from various Streptomyces species. A broad-spectrum antibiotic, it is used (generally as the sulfate salt) for the treatment of acute and chronic intestinal protozoal infections, but is not effective for extraintestinal protozoal infections. It is also used as a therapeutic against visceral leishmaniasis. Paromomycin: An aminoglycoside antibacterial and antiprotozoal agent produced by species of STREPTOMYCES. | amino cyclitol glycoside; aminoglycoside antibiotic | anthelminthic drug; antibacterial drug; antiparasitic agent; antiprotozoal drug |
| puromycin | puromycins | antiinfective agent; antimicrobial agent; antineoplastic agent; EC 3.4.11.14 (cytosol alanyl aminopeptidase) inhibitor; EC 3.4.14.2 (dipeptidyl-peptidase II) inhibitor; nucleoside antibiotic; protein synthesis inhibitor | |
| netilmicin | Netilmicin: Semisynthetic 1-N-ethyl derivative of SISOMYCIN, an aminoglycoside antibiotic with action similar to gentamicin, but less ear and kidney toxicity. | ||
| linezolid | acetamides; morpholines; organofluorine compound; oxazolidinone | antibacterial drug; protein synthesis inhibitor | |
| zithromax | azithromycin : A macrolide antibiotic useful for the treatment of bacterial infections. Azithromycin: A semi-synthetic macrolide antibiotic structurally related to ERYTHROMYCIN. It has been used in the treatment of Mycobacterium avium intracellulare infections, toxoplasmosis, and cryptosporidiosis. | macrolide antibiotic | antibacterial drug; environmental contaminant; xenobiotic |
| tiamulin | tiamulin : A carbotricyclic compound that is pleuromutilin in which the hydroxyacetate group is replaced by a 2-{[2-(diethylamino)ethyl]sulfanyl}acetate group. An antibacterial drug, tiamulin is used in veterinary medicine (generally as its hydrogen fumarate salt) for the treatment of swine dysentery caused by Serpulina hyodysenteriae. tiamulin: 81723 HFU and tiamutin are for fumarate salt; prevents senescence in ascomycete; pleuromutilin derivative; RN given refers to ((3aS-(3aalpha,4beta,5alpha,6alpha,8beta,9alpha,9abeta,10S*))-isomer | carbotricyclic compound; carboxylic ester; cyclic ketone; organic sulfide; secondary alcohol; semisynthetic derivative; tertiary amino compound; tetracyclic diterpenoid | antibacterial drug |
| hmr 3647 | |||
| josamycin | acetate ester; aldehyde; disaccharide derivative; glycoside; macrolide antibiotic; tertiary alcohol; tertiary amino compound | antibacterial drug; metabolite | |
| albocycline | albocycline: macrolide antibiotic isolated from Streptomyces bruneogriseus nov. sp. MCRL-0129; specifically anti-staphylococcal, including antibiotic-resistant strains; structure | macrolide | |
| evernimicin | |||
| gentamicin sulfate | |||
| pristinamycin iib | virginiamycin M2: structure in first source | ||
| cem 101 | solithromycin: an antibacterial fluoroketolide; structure in first source | ||
| tetracycline | tetracycline : A broad-spectrum polyketide antibiotic produced by the Streptomyces genus of actinobacteria. Tetracycline: A naphthacene antibiotic that inhibits AMINO ACYL TRNA binding during protein synthesis. | ||
| eravacycline | eravacycline: has antibacterial activity | tetracyclines |