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Molecular Microbiology Oct 1990Many microorganisms metabolize their substrates (precursors) only partially and excrete the products of the metabolism into the medium. Although uptake of precursor and... (Review)
Review
Many microorganisms metabolize their substrates (precursors) only partially and excrete the products of the metabolism into the medium. Although uptake of precursor and exit of product can proceed as two independent steps, there is increasing evidence that these processes are often linked and that transport is facilitated by a single antiport mechanism. Features of antiport mechanisms and advantages for the organism of catalysing precursor/product antiport will be illustrated by discussing a number of well-characterized systems. Based on precursor-product conversion stoichiometries, structural relatedness between precursors and products, and energetic and kinetic considerations, new examples of antiport systems will be proposed.
Topics: Bacteria; Biological Transport, Active
PubMed: 2077354
DOI: 10.1111/j.1365-2958.1990.tb00539.x -
Experimental and Therapeutic Medicine Feb 2020-Allyl-L-cysteine sulfoxide (ACSO) is an odour precursor in garlic bulbs. One plausible pathway for the biosynthesis of ACSO involves -2-carboxypropyl glutathione... (Review)
Review
-Allyl-L-cysteine sulfoxide (ACSO) is an odour precursor in garlic bulbs. One plausible pathway for the biosynthesis of ACSO involves -2-carboxypropyl glutathione produced from glutathione and methacrylic acid via valine or from γ-glutamyl cysteine. The elimination of glycine and glutamic acid from -2-carboxypropyl glutathione produces -2-carboxypropyl cysteine, which is converted to -allyl cysteine by decarboxylation and oxidation. -Allyl cysteine is also biosynthesized via the elimination of glutamic acid from γ-glutamyl -allyl cysteine by γ-glutamyl transpeptidase. The sulfur oxidation of -allyl cysteine by flavin-containing monooxygenase forms ACSO. When cells are damaged by slicing or grating, ACSO in the cytoplasm or cytoplasmic vesicle is immediately converted to allylsulfenic acid, pyruvic acid, and ammonia by alliinase (C-S lyase), which is located in the vacuoles of vascular bundle sheath cells. Two molecules of allylsulfenic acid form diallyl thiosulfinate (allicin), which exhibits potent antimicrobial activity. Allicin eventually yields garlic odour compounds, such as diallyl disulfide (DADS) and diallyl trisulfide (DATS). Although these sulfides are known to exert various physiological functions, their strong odour limits their use in foods. On the other hand, ACSO is water-soluble and odourless and enhances sweet, salty, and umami tastes, characteristics of which are desirable for food additives. Upon consumption, ACSO is primarily absorbed from the small intestine in the intact form, but is also partly decomposed to allylsulfenic acid, pyruvic acid and ammonia. Allylsulfenic acid is then further converted to DADS and diallyl monosulfide (DAS). ACSO has numerous functions, such as the prevention of diabetes, myocardial ischaemia, hepatic injury, platelet aggregation and blood ethanol elevation. Although some of these effects may be attributed to its metabolites, ACSO itself contributes to many of these physiological functions.
PubMed: 32010334
DOI: 10.3892/etm.2019.8385 -
Annals of the New York Academy of... Apr 2005The prolactin-releasing hormone (PRLH) is implicated in food intake and is expressed in several parts of the mammalian brain. The origin of the peptide precursor (PRH)... (Review)
Review
The prolactin-releasing hormone (PRLH) is implicated in food intake and is expressed in several parts of the mammalian brain. The origin of the peptide precursor (PRH) has been unclear, and the only feature resembling other known human neuropeptide sequences is the C-terminal RF-motif, also present in the neuropeptide FF and the neuropeptide RF amide-related peptide families (RFRP). We have recently found sequences of PRH and the closely related precursor C-RF amide in chicken, shedding light on the PRH ancestry.
Topics: Animals; Humans; Protein Precursors; Structural Homology, Protein; Thyrotropin-Releasing Hormone
PubMed: 15891064
DOI: 10.1196/annals.1327.064 -
Cell Aug 1989
Review
Topics: Aging; Alzheimer Disease; Amyloid; Amyloid beta-Protein Precursor; Brain; Humans; Protein Precursors
PubMed: 2504495
DOI: 10.1016/0092-8674(89)90093-7 -
Biochimie May 2009Protealysin, a protease previously described by us in Serratia proteamaculans, belongs to the group of thermolysin-like proteases (TLPs) that differ from classical TLPs...
Protealysin, a protease previously described by us in Serratia proteamaculans, belongs to the group of thermolysin-like proteases (TLPs) that differ from classical TLPs by the precursor structural organization. The propeptide of protealysin precursor has no significant structural similarity to the propeptides of most TLPs. The functions of protealysin-like precursors and mechanisms of their action remain unclear. We studied the pathway of protealysin precursor processing in vitro using standard approaches: modification of the catalytic site and monitoring immobilized precursor maturation. The Glu(113) --> Ala substitution inhibited the precursor maturation, which pointed to the autocatalytic processing. The mutant precursor exposure to active protealysin converted it to the mature enzyme, thus, indicating the intermolecular processing. Intermolecular processing of the mutant protein by other proteases such as thermolysin or subtilisin is also possible. The intact protealysin precursor was efficiently autoprocessed in solution but not after immobilization. These data indicate that the processing of protealysin precursor differs from that of classical TLPs. The protealysin propeptide is cleaved by an autocatalytic or heterocatalytic intermolecular mechanism and is most likely not removed intramolecularly.
Topics: Bacterial Proteins; Genetic Vectors; Hydrogen-Ion Concentration; Kinetics; Protein Precursors; Serratia; Thermolysin
PubMed: 19324072
DOI: 10.1016/j.biochi.2009.03.008 -
Journal of Neurochemistry Feb 1991Amyloid A4 protein (beta-protein) is deposited in the brain of a patient with Alzheimer's disease (AD) as one of the main components of extracellular cerebrovascular... (Review)
Review
Amyloid A4 protein (beta-protein) is deposited in the brain of a patient with Alzheimer's disease (AD) as one of the main components of extracellular cerebrovascular amyloid, as well as neurofibrillary tangles. It is derived from a precursor protein, and its formation has been considered to be a rate-limiting step for brain degeneration in AD. In this article, proteolytic cleavage events that can degrade amyloid precursor protein are reviewed with respect to how the topographical distribution of the proteinase and its substrates disturbs normal processing steps in AD brain.
Topics: Alzheimer Disease; Amino Acid Sequence; Amyloid beta-Peptides; Amyloid beta-Protein Precursor; Animals; Brain; Endopeptidases; Humans; Molecular Sequence Data; Protein Precursors
PubMed: 1899108
DOI: 10.1111/j.1471-4159.1991.tb08160.x -
Science (New York, N.Y.) Jun 1990
Review
Topics: Alzheimer Disease; Amyloid; Amyloid beta-Protein Precursor; Animals; Brain; Humans; Molecular Structure; Mutation; Nerve Tissue Proteins; Protein Precursors; Protein Processing, Post-Translational
PubMed: 2111582
DOI: 10.1126/science.2111582 -
Annals of the New York Academy of... 1992
Review
Topics: Amino Acid Sequence; Animals; Cats; Dogs; Humans; Molecular Sequence Data; Neurotensin; Pepsin A; Peptides; Protein Precursors; Protein Processing, Post-Translational; Protein Structure, Secondary
PubMed: 1463268
DOI: 10.1111/j.1749-6632.1992.tb27335.x -
Cell Dec 1979An immediate precursor of 5S ribosomal RNA (rRNA) from Bacillus subtilis has 21 and 42 nucleotide precursor-specific segments associated with its 5' and 3' termini,...
An immediate precursor of 5S ribosomal RNA (rRNA) from Bacillus subtilis has 21 and 42 nucleotide precursor-specific segments associated with its 5' and 3' termini, respectively. On the basis of its nucleotide sequence, predicted secondary structure and location in the rRNA transcriptional unit, the 3' precursor element apparently functions during the termination of transcription. A portion of the 5' precursor element is shown to facilitate the native folding of the mature domain of the precursor. Precursor 5S rRNA molecules which lack the 5' terminal 8-9 nucleotides of the 5' precursor elements were fabricated. These abbreviated constructs assume a non-native conformation, as revealed by their behavior during polyacrylamide gel electrophoresis. The aberrant conformation is evidently forced upon the abbreviated constructs by the residual 5' precursor sequence, since its removal by the maturation endonuclease RNAase M5 precipitates the reordering of the mature domain into its native conformation. Inspection of the nucleotide sequence of the 5S precursor suggested the nature of the conformational aberration, and gel electrophoresis analyses of limited nuclease digests of end-labeled precursors in the native and aberrant conformations are consistent with the derived model. We conclude taht the 5' terminal six nucleotides in the intact 5S precursor assist in the folding of the mature domain by forming a base-paired duplex with neighboring nucleotides, thereby preventing that adjacent sequence from engendering the abnormal conformation. The involvement of precursor-specific sequences and conformational dynamics in RNA function are discussed.
Topics: Bacillus subtilis; Base Sequence; Nucleic Acid Conformation; Nucleic Acid Precursors; RNA, Bacterial; RNA, Ribosomal; Ribonucleases; Temperature; Transcription, Genetic
PubMed: 117902
DOI: 10.1016/0092-8674(79)90226-5 -
Multiple precursor proteins bind individual Tat receptor complexes and are collectively transported.The EMBO Journal May 2010The thylakoid twin arginine protein translocation (Tat) system is thought to have a multivalent receptor complex with each cpTatC-Hcf106 pair constituting a signal...
The thylakoid twin arginine protein translocation (Tat) system is thought to have a multivalent receptor complex with each cpTatC-Hcf106 pair constituting a signal peptide-binding unit. Conceptual models suggest that translocation of individual precursor proteins occurs upon assembly of a Tha4 oligomer with a precursor-occupied cpTatC-Hcf106. However, results reported here reveal that multiple precursor proteins bound to a single receptor complex can be transported together. Precursor proteins that contain one or two cysteine residues readily formed intermolecular disulphide bonds upon binding to the receptor complex, resulting in dimeric and tetrameric precursor proteins. Three lines of evidence indicate that all members of precursor oligomers were specifically bound to a receptor unit. Blue native-polyacrylamide gel electrophoresis analysis showed that oligomers were present on individual receptor complexes rather than bridging two or more receptor complexes. Upon energizing the membrane, the dimeric and tetrameric precursors were transported across the membrane with efficiencies comparable with that of monomeric precursors. These results imply a novel aspect of Tat systems, whereby multiple precursor-binding sites can act in concert to transport an interlinked oligo-precursor protein.
Topics: Arginine; Cysteine; Disulfides; Intracellular Membranes; Membrane Transport Proteins; Pisum sativum; Plant Proteins; Protein Binding; Protein Multimerization; Protein Precursors; Protein Transport; Thylakoids
PubMed: 20339348
DOI: 10.1038/emboj.2010.44