Pantetheine
Pantothenic Acid
Coenzyme A
Tyrothricin
Cysteamine
Acetyl Coenzyme A
Fatty Acid Synthases
Analysis of 4-phosphopantetheinylation of polyhydroxybutyrate synthase from Ralstonia eutropha: generation of beta-alanine auxotrophic Tn5 mutants and cloning of the panD gene region. (1/116)
The postulated posttranslational modification of the polyhydroxybutyrate (PHA) synthase from Ralstonia eutropha by 4-phosphopantetheine was investigated. Four beta-alanine auxotrophic Tn5-induced mutants of R. eutropha HF39 were isolated, and two insertions were mapped in an open reading frame with strong similarity to the panD gene from Escherichia coli, encoding L-aspartate-1-decarboxylase (EC 4.1.1.15), whereas two other insertions were mapped in an open reading frame (ORF) with strong similarity to the NAD(P)+ transhydrogenase (EC 1.6.1.1) alpha 1 subunit, encoded by the pntAA gene from Escherichia coli. The panD gene was cloned by complementation of the panD mutant of R. eutropha Q20. DNA sequencing of the panD gene region (3,312 bp) revealed an ORF of 365 bp, encoding a protein with 63 and 67% amino acid sequence similarity to PanD from E. coli and Bacillus subtilis, respectively. Subcloning of only this ORF into vectors pBBR1MCS-3 and pBluescript KS- led to complementation of the panD mutants of R. eutropha and E. coli SJ16, respectively. panD-encoded L-aspartate-1-decarboxylase was further confirmed by an enzymatic assay. Upstream of panD, an ORF with strong similarity to pntAA from E. coli, encoding NAD(P)+ transhydrogenase subunit alpha 1 was found; downstream of panD, two ORFs with strong similarity to pntAB and pntB, encoding subunits alpha 2 and beta of the NAD(P)+ transhydrogenase, respectively, were identified. Thus, a hitherto undetermined organization of pan and pnt genes was found in R. eutropha. Labeling experiments using one of the R. eutropha panD mutants and [2-14C]beta-alanine provided no evidence that R. eutropha PHA synthase is covalently modified by posttranslational attachment of 4-phosphopantetheine, nor did the E. coli panD mutant exhibit detectable labeling of functional PHA synthase from R. eutropha. (+info)Aminoacyl-CoAs as probes of condensation domain selectivity in nonribosomal peptide synthesis. (2/116)
In nonribosomal biosynthesis of peptide antibiotics by multimodular synthetases, amino acid monomers are activated by the adenylation domains of the synthetase and loaded onto the adjacent carrier protein domains as thioesters, then the formation of peptide bonds and translocation of the growing chain are effected by the synthetase's condensation domains. Whether the condensation domains have any editing function has been unknown. Synthesis of aminoacyl-coenzyme A (CoA) molecules and direct enzymatic transfer of aminoacyl-phosphopantetheine to the carrier domains allow the adenylation domain editing function to be bypassed. This method was used to demonstrate that the first condensation domain of tyrocidine synthetase shows low selectivity at the donor residue (D-phenylalanine) and higher selectivity at the acceptor residue (L-proline) in the formation of the chain-initiating D-Phe-L-Pro dipeptidyl-enzyme intermediate. (+info)Dibromopropanone cross-linking of the phosphopantetheine and active-site cysteine thiols of the animal fatty acid synthase can occur both inter- and intrasubunit. Reevaluation of the side-by-side, antiparallel subunit model. (3/116)
The objective of this study was to test a new model for the homodimeric animal FAS which implies that the condensation reaction can be catalyzed by the amino-terminal beta-ketoacyl synthase domain in cooperation with the penultimate carboxyl-terminal acyl carrier protein domain of either subunit. Treatment of animal fatty acid synthase dimers with dibromopropanone generates three new molecular species with decreased electrophoretic mobilities; none of these species are formed by fatty acid synthase mutant dimers lacking either the active-site cysteine of the beta-ketoacyl synthase domain (C161A) or the phosphopantetheine thiol of the acyl carrier protein domain (S2151A). A double affinity-labeling strategy was used to isolate dimers that carried one or both mutations on one or both subunits; the heterodimers were treated with dibromopropanone and analyzed by a combination of sodium dodecyl sulfate/polyacrylamide gel electrophoresis, Western blotting, gel filtration, and matrix-assisted laser desorption mass spectrometry. Thus the two slowest moving of these species, which accounted for 45 and 15% of the total, were identified as doubly and singly cross-linked dimers, respectively, whereas the fastest moving species, which accounted for 35% of the total, was identified as originating from internally cross-linked subunits. These results show that the two polypeptides of the fatty acid synthase are oriented such that head-to-tail contacts are formed both between and within subunits, and provide the first structural evidence in support of the new model. (+info)Holo-(acyl carrier protein) synthase and phosphopantetheinyl transfer in Escherichia coli. (4/116)
Holo-(acyl carrier protein) synthase (AcpS) post-translationally modifies apoacyl carrier protein (apoACP) via transfer of 4'-phosphopantetheine from coenzyme A (CoA) to the conserved serine 36 gamma-OH of apoACP. The resulting holo-acyl carrier protein (holo-ACP) is then active as the central coenzyme of fatty acid biosynthesis. The acpS gene has previously been identified and shown to be essential for Escherichia coli growth. Earlier mutagenic studies isolated the E. coli MP4 strain, whose elevated growth requirement for CoA was ascribed to a deficiency in holoACP synthesis. Sequencing of the acpS gene from the E. coli MP4 strain (denoted acpS1) showed that the AcpS1 protein contains a G4D mutation. AcpS1 exhibited a approximately 5-fold reduction in its catalytic efficiency when compared with wild type AcpS, accounting for the E. coli MP4 strain phenotype. It is shown that a conditional acpS mutant accumulates apoACP in vivo under nonpermissive conditions in a manner similar to the E. coli MP4 strain. In addition, it is demonstrated that the gene product, YhhU, of a previously identified E. coli open reading frame can completely suppress the acpS conditional, lethal phenotype upon overexpression of the protein, suggesting that YhhU may be involved in an alternative pathway for phosphopantetheinyl transfer and holoACP synthesis in E. coli. (+info)Molecular characterization of lantibiotic-synthesizing enzyme EpiD reveals a function for bacterial Dfp proteins in coenzyme A biosynthesis. (5/116)
The lantibiotic-synthesizing flavoprotein EpiD catalyzes the oxidative decarboxylation of peptidylcysteines to peptidyl-aminoenethiols. The sequence motif responsible for flavin coenzyme binding and enzyme activity is conserved in different proteins from all kingdoms of life. Dfp proteins of eubacteria and archaebacteria and salt tolerance proteins of yeasts and plants belong to this new family of flavoproteins. The enzymatic function of all these proteins was not known, but our experiments suggested that they catalyze a similar reaction like EpiD and/or may have similar substrates and are homododecameric flavoproteins. We demonstrate that the N-terminal domain of the Escherichia coli Dfp protein catalyzes the decarboxylation of (R)-4'-phospho-N-pantothenoylcysteine to 4'-phosphopantetheine. This reaction is essential for coenzyme A biosynthesis. (+info)Identification of an NADH-linked disulfide reductase from Bacillus megaterium specific for disulfides containing pantethine 4',4''-diphosphate moieties. (6/116)
Bacillus megaterium contains an NADH-linked disulfide reductase that is specific for disulfides containing pantethine 4',4''-diphosphate moieties. This reductase is at its highest level in cells late in sporulation and in dormant spores, and could be involved in the formation and cleavage of coenzyme A-protein disulfides which take place late in sporulation and early in spore germination, respectively. (+info)Purification, priming, and catalytic acylation of carrier protein domains in the polyketide synthase and nonribosomal peptidyl synthetase modules of the HMWP1 subunit of yersiniabactin synthetase. (7/116)
The 207-kDa polyketide synthase (PKS) module (residues 1-1895) and the 143-kDa nonribosomal peptidyl synthetase (NRPS) module (1896-3163) of the 350-kDa HMWP1 subunit of yersiniabactin synthetase have been expressed in and purified from Escherichia coli in soluble forms to characterize the acyl carrier protein (ACP) domain of the PKS module and the homologous peptidyl carrier protein (PCP(3)) domain of the NRPS module. The apo-ACP and PCP domains could be selectively posttranslationally primed by the E. coli ACPS and EntD phosphopantetheinyl transferases (PPTases), respectively, whereas the Bacillus subtilis PPTase Sfp primed both carrier protein domains in vitro or during in vivo coexpression. The holo-NRPS module but not the holo-PKS module was then selectively aminoacylated with cysteine by the adenylation domain embedded in the HMWP2 subunit of yersiniabactin synthetase, acting in trans. When the acyltransferase (AT) domain of HMWP1 was analyzed for its ability to malonylate the holo carrier protein domains, in cis acylation was first detected. Then, in trans malonylation of the excised holo-ACP or holo-PCP(3)-TE fragments by HMWP1 showed both were malonylated with a 3:1 catalytic efficiency ratio, showing a promiscuity to the AT domain. (+info)Arabidopsis thaliana flavoprotein AtHAL3a catalyzes the decarboxylation of 4'-Phosphopantothenoylcysteine to 4'-phosphopantetheine, a key step in coenzyme A biosynthesis. (8/116)
The Arabidopsis thaliana flavoprotein AtHAL3a is related to plant growth and salt and osmotic tolerance. AtHAL3a shows sequence homology to the bacterial flavoproteins EpiD and Dfp. EpiD, Dfp, and AtHAL3a are members of the homo-oligomeric flavin-containing Cys decarboxylase (HFCD) protein family. We demonstrate that AtHAL3a catalyzes the decarboxylation of (R)-4'-phospho-N-pantothenoylcysteine to 4'-phosphopantetheine. This key step in coenzyme A biosynthesis is catalyzed in bacteria by the Dfp proteins. Exchange of His-90 of AtHAL3a for Asn led to complete inactivation of the enzyme. Dfp and AtHAL3a are characterized by a shortened substrate binding clamp compared with EpiD. Exchange of the cysteine residue of the conserved ACGD motif of this binding clamp resulted in loss of (R)-4'-phospho-N-pantothenoylcysteine decarboxylase activity. Based on the crystal structures of EpiD H67N with bound substrate peptide and of AtHAL3a, we present a model for the binding of (R)-4'-phospho-N-pantothenoylcysteine to AtHAL3a. (+info)Pantetheine is not a medical term per se, but it is a biochemical compound with relevance to medicine. Pantetheine is the alcohol form of pantothenic acid (vitamin B5), and it plays a crucial role in the metabolism of proteins, carbohydrates, and fats. It is a component of coenzyme A, which is involved in numerous biochemical reactions within the body.
Coenzyme A, containing pantetheine, participates in oxidation-reduction reactions, energy production, and the synthesis of various compounds, such as fatty acids, cholesterol, steroid hormones, and neurotransmitters. Therefore, pantetheine is essential for maintaining proper cellular function and overall health.
While there isn't a specific medical condition associated with pantetheine deficiency, ensuring adequate intake of vitamin B5 (through diet or supplementation) is vital for optimal health and well-being.
Pantothenic Acid, also known as Vitamin B5, is a water-soluble vitamin that plays a vital role in the metabolism of proteins, carbohydrates, and fats. It is essential for the synthesis of coenzyme A (CoA), which is involved in various biochemical reactions in the body, including energy production, fatty acid synthesis, and cholesterol metabolism.
Pantothenic Acid is widely distributed in foods, including meat, poultry, fish, whole grains, legumes, and vegetables. Deficiency of this vitamin is rare but can lead to symptoms such as fatigue, irritability, sleep disturbances, muscle cramps, and gastrointestinal problems.
In addition to its role in metabolism, Pantothenic Acid also has potential benefits for wound healing, reducing inflammation, and supporting the immune system.
Coenzyme A, often abbreviated as CoA or sometimes holo-CoA, is a coenzyme that plays a crucial role in several important chemical reactions in the body, particularly in the metabolism of carbohydrates, fatty acids, and amino acids. It is composed of a pantothenic acid (vitamin B5) derivative called pantothenate, an adenosine diphosphate (ADP) molecule, and a terminal phosphate group.
Coenzyme A functions as a carrier molecule for acetyl groups, which are formed during the breakdown of carbohydrates, fatty acids, and some amino acids. The acetyl group is attached to the sulfur atom in CoA, forming acetyl-CoA, which can then be used as a building block for various biochemical pathways, such as the citric acid cycle (Krebs cycle) and fatty acid synthesis.
In summary, Coenzyme A is a vital coenzyme that helps facilitate essential metabolic processes by carrying and transferring acetyl groups in the body.
Tyrothricin is not typically considered a medical term, but it is a chemical compound with some medical applications. Medically, tyrothricin is often referred to as a polypeptide antibiotic, which is derived from the gram-positive bacteria Bacillus brevis. It is a complex mixture of several chemically related polypeptides, including tyrocidine and gramicidin. Tyrothricin has broad-spectrum antimicrobial activity against many gram-positive and gram-negative bacteria, as well as some fungi and viruses. However, its clinical use is limited due to its potential toxicity and the availability of safer and more effective antibiotics.
Cysteamine is a medication and a naturally occurring aminothiol compound, which is composed of the amino acid cysteine and a sulfhydryl group. It has various uses in medicine, including as a treatment for cystinosis, a rare genetic disorder that causes an accumulation of cystine crystals in various organs and tissues. Cysteamine works by reacting with cystine to form a compound that can be more easily eliminated from the body. It is available in oral and topical forms and may also be used for other indications, such as treating lung diseases and radiation-induced damage.
Acetyl Coenzyme A, often abbreviated as Acetyl-CoA, is a key molecule in metabolism, particularly in the breakdown and oxidation of carbohydrates, fats, and proteins to produce energy. It is a coenzyme that plays a central role in the cellular process of transforming the energy stored in the chemical bonds of nutrients into a form that the cell can use.
Acetyl-CoA consists of an acetyl group (two carbon atoms) linked to coenzyme A, a complex organic molecule. This linkage is facilitated by an enzyme called acetyltransferase. Once formed, Acetyl-CoA can enter various metabolic pathways. In the citric acid cycle (also known as the Krebs cycle), Acetyl-CoA is further oxidized to release energy in the form of ATP, NADH, and FADH2, which are used in other cellular processes. Additionally, Acetyl-CoA is involved in the biosynthesis of fatty acids, cholesterol, and certain amino acids.
In summary, Acetyl Coenzyme A is a vital molecule in metabolism that connects various biochemical pathways for energy production and biosynthesis.
Fatty acid synthases (FAS) are a group of enzymes that are responsible for the synthesis of fatty acids in the body. They catalyze a series of reactions that convert acetyl-CoA and malonyl-CoA into longer chain fatty acids, which are then used for various purposes such as energy storage or membrane formation.
The human genome encodes two types of FAS: type I and type II. Type I FAS is a large multifunctional enzyme complex found in the cytoplasm of cells, while type II FAS consists of individual enzymes located in the mitochondria. Both types of FAS play important roles in lipid metabolism, but their regulation and expression differ depending on the tissue and physiological conditions.
Inhibition of FAS has been explored as a potential therapeutic strategy for various diseases, including cancer, obesity, and metabolic disorders. However, more research is needed to fully understand the complex mechanisms regulating FAS activity and its role in human health and disease.
Sulfhydryl compounds, also known as thiol compounds, are organic compounds that contain a functional group consisting of a sulfur atom bonded to a hydrogen atom (-SH). This functional group is also called a sulfhydryl group. Sulfhydryl compounds can be found in various biological systems and play important roles in maintaining the structure and function of proteins, enzymes, and other biomolecules. They can also act as antioxidants and help protect cells from damage caused by reactive oxygen species. Examples of sulfhydryl compounds include cysteine, glutathione, and coenzyme A.