scholarly journals Post translational modifications of Trifolitoxin: a blue fluorescent peptide antibiotic*

2022 ◽  
Author(s):  
Benjamin J. Lethbridge ◽  
Robert E. Asenstorfer ◽  
Laura S. Bailey ◽  
Brenda T. Breil ◽  
Jodie V. Johnson ◽  
...  
Keyword(s):  
Brucella Abortus ◽  
Rhizobium Leguminosarum ◽  
Heterocyclic Ring ◽  
Side Chain ◽  
Peptide Antibiotic ◽  
Geometric Isomers ◽  
Post Translational Modifications ◽  
Plant Symbiont ◽  
Fluorescent Peptide ◽  
Primary Amino

AbstractTrifolitoxin (TFX, C41H63N15O15S) is a selective, ribosomally-synthesized, post-translationally modified, peptide antibiotic, produced by Rhizobium leguminosarum bv. trifolii T24. TFX specifically inhibits α-proteobacteria, including the plant symbiont Rhizobium spp., the plant pathogen Agrobacterium spp. and the animal pathogen Brucella abortus. TFX-producing strains prevent legume root nodulation by TFX-sensitive rhizobia. TFX has been isolated as a pair of geometric isomers, TFX1 and TFX2, which are derived from the biologically inactive primary amino acid sequence: Asp-Ile-Gly-Gly-Ser-Arg-Gln-Gly-Cys-Val-Ala. Gly-Cys is present as a thiazoline ring and the Arg-Gln-Gly sequence is extensively modified to a UV absorbing, blue fluorescent chromophore. The chromophore consists of a conjugated, 5-membered heterocyclic ring and side chain of modified glutamine.

Characterization of acetylated histidine b1-ion structure: A competition between oxazolone and side chain imidazole moiety

2018 ◽  
Vol 24 (3) ◽  
pp. 261-268 ◽  
Author(s):  
Kranthikumar Yadav ◽  
J Laxmikanth Rao ◽  
R Srinivas ◽  
R Nagaraj ◽  
MV Jagannadham
Keyword(s):  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Mass Spectrometric Study ◽  
Research Area ◽  
Side Chain ◽  
Oxazolone Structure ◽  
Post Translational Modifications ◽  
Tandem Mass Spectrometric ◽  
Oxazolone Ring

The detection of post-translational modifications of proteins is an important comprehensive research area. Over the years, proteomic studies involving protein acetylation have attracted a great deal of attention. In the present study, we have focussed on the acetylation of histidine and the intrinsic stability of b1-ion of oxazolone ring and/or with side chain imidazole bicyclic product. The formation of oxazolone structure may occur when an amino moiety undergoes acetylation reaction and when it is present in the vicinity of the side chain imidazole moiety. Tryptic peptides generated from the proteins of Acenitobacter radioresistens MMC5-containing N-terminal histidine were explored in a standard proteomic workflow. Formation of [Formula: see text] ion with an oxazolone ring in these peptides has been supported by a tandem mass spectrometric study of a synthetic peptide and density functional theory calculations. The results obtained from this study have implications in understanding the fragmentation of the peptides generated in the proteomic workflows.

scholarly journals Studies on the synthesis and stability of α-ketoacyl peptides

Amino Acids ◽  
2020 ◽  
Vol 52 (10) ◽  
pp. 1425-1438
Author(s):  
Johann Sajapin ◽  
Michael Hellwig
Keyword(s):  
Peptide Bond ◽  
Side Chain ◽  
Peptide Backbone ◽  
Post Translational Modifications ◽  
Degradation Reactions ◽  
Keto Acids ◽  
Strecker Aldehydes ◽  
The Stability ◽  
Dehydration Processes ◽  
Hydrolysis Of

Abstract Oxidative stress, an excess of reactive oxygen species (ROS), may lead to oxidative post-translational modifications of proteins resulting in the cleavage of the peptide backbone, known as α-amidation, and formation of fragments such as peptide amides and α-ketoacyl peptides (α-KaP). In this study, we first compared different approaches for the synthesis of different model α-KaP and then investigated their stability compared to the corresponding unmodified peptides. The stability of peptides was studied at room temperature or at temperatures relevant for food processing (100 °C for cooking and 150 °C as a simulation of roasting) in water, in 1% (m/v) acetic acid or as the dry substance (to simulate the thermal treatment of dehydration processes) by HPLC analysis. Oxidation of peptides by 2,5-di-tert-butyl-1,4-benzoquinone (DTBBQ) proved to be the most suited method for synthesis of α-KaPs. The acyl side chain of the carbonyl-terminal α-keto acid has a crucial impact on the stability of α-KaPs. This carbonyl group has a catalytic effect on the hydrolysis of the neighboring peptide bond, leading to the release of α-keto acids. Unmodified peptides were significantly more stable than the corresponding α-KaPs. The possibility of further degradation reactions was shown by the formation of Schiff bases from glyoxylic or pyruvic acids with glycine and proven through detection of transamination products and Strecker aldehydes of α-keto acids by HPLC–MS/MS. We propose here a mechanism for the decomposition of α-ketoacyl peptides.

scholarly journals Evaluation of Brucella abortus Phosphoglucomutase (pgm) Mutant as a New Live Rough-Phenotype Vaccine

2003 ◽  
Vol 71 (11) ◽  
pp. 6264-6269 ◽  
Author(s):  
Juan Esteban Ugalde ◽  
Diego José Comerci ◽  
M. Susana Leguizamón ◽  
Rodolfo Augusto Ugalde
Keyword(s):  
Brucella Abortus ◽  
Cytokine Production ◽  
Side Chain ◽  
Bovine Brucellosis ◽  
Vaccine Candidates ◽  
Th1 Response ◽  
O Antigen ◽  
Intracellular Multiplication ◽  
Fluorescence Polarization Assay ◽  
Antigen Antibody

ABSTRACT Brucella abortus S19 is the vaccine most frequently used against bovine brucellosis. Although it induces good protection levels, it cannot be administered to pregnant cattle, revaccination is not advised due to interference in the discrimination between infected and vaccinated animals during immune-screening procedures, and the vaccine is virulent for humans. Due to these reasons, there is a continuous search for new bovine vaccine candidates that may confer protection levels comparable to those conferred by S19 but without its disadvantages. A previous study characterized the phenotype associated with the phosphoglucomutase (pgm) gene disruption in Brucella abortus S2308, as well as the possible role for the smooth lipopolysaccharide (LPS) in virulence and intracellular multiplication in HeLa cells (J. E. Ugalde, C. Czibener, M. F. Feldman, and R. A. Ugalde, Infect. Immun. 68:5716-5723, 2000). In this report, we analyze the protection, proliferative response, and cytokine production induced in BALB/c mice by a Δpgm deletion strain. We show that this strain synthesizes O antigen with a size of approximately 45 kDa but is rough. This is due to the fact that the Δpgm strain is unable to assemble the O side chain in the complete LPS. Vaccination with the Δpgm strain induced protection levels comparable to those induced by S19 and generated a proliferative splenocyte response and a cytokine profile typical of a Th1 response. On the other hand, we were unable to detect a specific anti-O-antigen antibody response by using the fluorescence polarization assay. In view of these results, the possibility that the Δpgm mutant could be used as a vaccination strain is discussed.

scholarly journals (2R,4R)-4-(2-Ethoxy-2-oxoethyl)-2,6,6-trimethyl–2-oxo-1,3,6,2λ5-dioxazaphosphocan-6-ium iodide

2012 ◽  
Vol 68 (6) ◽  
pp. o1596-o1596
Author(s):  
Bradford W. Fulfer ◽  
Frank R. Fronczek ◽  
Steven F. Watkins
Keyword(s):  
Title Compound ◽  
Chair Conformation ◽  
Heterocyclic Ring ◽  
Side Chain ◽  
Boat Conformation ◽  
Compound C ◽  
Chiral Centers

The title compound, C11H23NO5P+·I−, consists of an eight-membered cationic heterocyclic ring in a boat–chair conformation. The ring features a tetraalkylammonium N and a methylphosphonate P atom. A –CH2(CO)OC2H5 ester side chain at the C adjacent to oxygen produces two chiral centers at that substituted C atom and the P atom, both of which were determined to have absolute R,R configurations. A previously determined racemic bromide analog has exactly the same ring but with a –C15H31 side chain. In that structure, both chiral centers show the same relative R/S,R/S configurations, but the ring in the bromide analog is in a boat conformation.

scholarly journals Genetic Characterization of a Tn5-Disrupted Glycosyltransferase Gene Homolog in Brucella abortus and Its Effect on Lipopolysaccharide Composition and Virulence

1999 ◽  
Vol 67 (8) ◽  
pp. 3830-3835 ◽  
Author(s):  
J. R. McQuiston ◽  
R. Vemulapalli ◽  
T. J. Inzana ◽  
G. G. Schurig ◽  
N. Sriranganathan ◽  
...  
Keyword(s):  
Brucella Abortus ◽  
Genomic Dna ◽  
Homology Search ◽  
Side Chain ◽  
Broad Host Range ◽  
Genomic Fragment ◽  
Wild Type ◽  
Reading Frame ◽  
Whole Cells ◽  
Chain Synthesis

ABSTRACT We constructed a rough mutant of Brucella abortus 2308 by transposon (Tn5) mutagenesis. Neither whole cells nor extracted lipopolysaccharide (LPS) from this mutant, designated RA1, reacted with a Brucella O-side-chain-specific monoclonal antibody (MAb), Bru-38, indicating the absence of O-side-chain synthesis. Compositional analyses of LPS from strain RA1 showed reduced levels of quinovosamine and mannose relative to the levels in the parental, wild-type strain, 2308. We isolated DNA flanking the Tn5 insertion in strain RA1 by cloning a 25-kbXbaI genomic fragment into pGEM-3Z to create plasmid pJM6. Allelic exchange of genomic DNA in B. abortus 2308 mediated by electroporation of pJM6 produced kanamycin-resistant clones that were not reactive with MAb Bru-38. Southern blot analysis of genomic DNA from these rough clones revealed Tn5 in a 25-kbXbaI genomic fragment. A homology search with the deduced amino acid sequence of the open reading frame disrupted by Tn5 revealed limited homology with various glycosyltransferases. This B. abortus gene has been namedwboA. Transformation of strain RA1 with a broad-host-range plasmid bearing the wild-type B. abortus wboA gene resulted in the restoration of O-side-chain synthesis and the smooth phenotype.B. abortus RA1 was attenuated for survival in mice. However, strain RA1 persisted in mice spleens for a longer time than the B. abortus vaccine strain RB51, but as expected, neither strain induced antibodies specific for the O side chain.

Gausemycins A,B – Cyclic Lipoglycopeptides from Streptomyces Sp.

2020 ◽  
Author(s):  
Anton Tyurin ◽  
Vera Alferova ◽  
Alexander Paramonov ◽  
Maxim Shuvalov ◽  
Gulnara Kudryakova ◽  
...  
Keyword(s):  
Cyclic Peptides ◽  
Pore Formation ◽  
Structural Features ◽  
Side Chain ◽  
Peptide Antibiotic ◽  
Streptomyces Sp ◽  
Gram Positive Bacteria ◽  
Low Concentrations ◽  
Phenylbutyric Acid ◽  
Peptide Core

We report a novel family of natural lipoglycopeptides produced by Streptomyces sp. INA-Ac-5812. Two major components of the mixture, named gausemycins A and B, were isolated, and their structures were elucidated. The compounds are cyclic peptides with a unique peptide core and several remarkable structural features, including unusual positions of D-amino acids, lack of the Ca2+ -binding Asp-X-Asp-Gly (DXDG) motif, tyrosine glycosylation with arabinose, presence of 2-amino-4-hydroxy-4- phenylbutyric acid (Ahpb) and chlorinated kynurenine (ClKyn), N-acylation of the ornithine side chain. These major components of the peptide antibiotic family have pronounced activity against Gram-positive bacteria. The mechanism of action of gausemycins was explored by a number of methods, showing significant differences compared to glycopeptides and related lipopeptides. For example, gausemycins exhibit no Ca2+ -dependence of antimicrobial activity and induce no pore formation at low concentrations. Moreover, there is no detectable accumulation of cell wall biosynthesis precursors under treatment with gausemycins.

Identification of Lysine Carboxylation Sites in Proteins by Integrating Statistical Moments and Position Relative Features via General PseAAC

2020 ◽  
Vol 15 (5) ◽  
pp. 396-407 ◽  
Author(s):  
Saba Amanat ◽  
Adeel Ashraf ◽  
Waqar Hussain ◽  
Nouman Rasool ◽  
Yaser D. Khan
Keyword(s):  
Prediction Model ◽  
Model Validation ◽  
Cross Validation ◽  
Covalent Attachment ◽  
Side Chain ◽  
Consistency Test ◽  
Post Translational Modifications ◽  
Independent Dataset ◽  
Proposed Model ◽  
Self Consistency

Background: Carboxylation is one of the most biologically important post-translational modifications and occurs on lysine, arginine, and glutamine residues of a protein. Among all these three, the covalent attachment of the carboxyl group with the lysine side chain is the most frequent and biologically important type of carboxylation. For studying such biological functions, it is essential to correctly determine the lysine sites sensitive to carboxylation. Objective: Herein, we present a computational model for the prediction of the carboxylysine site which is based on machine learning. Methods: Various position and composition relative features have been incorporated into the Pse- AAC for construction of feature vectors and a neural network is employed as a classifier. The model is validated by jackknife, cross-validation, self-consistency, and independent testing. Results: The results of the self-consistency test elaborated that model has 99.76% Acc, 99.76% Sp, 99.76% Sp, and 0.99 MCC..Using the jackknife method, prediction model validation gave 97.07% Acc, while for 10-fold cross-validation, prediction model validation gave 95.16% Acc. Conclusion: The results of independent dataset testing were 94.3% which illustrated that the proposed model has better performance as compared to the existing model PreLysCar; however, the accuracy can be improved further, in the future, due to the increasing number of carboxylysine sites in proteins.

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