scholarly journals Conformation and membrane interaction studies of the potent antimicrobial and anticancer peptide palustrin-Ca

2021 ◽  
Author(s):  
Patrick Brendan Timmons ◽  
Chandralal M Hewage
Keyword(s):  
Sodium Dodecyl ◽  
Three Dimensional ◽  
Dynamics Simulation ◽  
Peptide Sequence ◽  
Helical Conformation ◽  
Dimensional Structure ◽  
Amino Acid Residues ◽  
Anticancer Activities ◽  
American Bullfrog ◽  
Α Helix

Palustrin-Ca (GFLDIIKDTGKEFAVKILNNLKCKLAGGCPP) is a host defense peptide with potent antimicrobial and anticancer activities, first isolated from the skin of the American bullfrog Lithobates catesbeianus. The peptide is 31 amino acid residues long, cationic and amphipathic. Two-dimensional NMR spectroscopy was employed to characterise its three-dimensional structure in a 50/50% water/2,2,2-trifluoroethanol-d3 mixture. The structure is defined by an α-helix that spans between Ile6-Ala26, and a cyclic disulphide bridged domain at the C-terminal end of the peptide sequence, between residues 23 and 29. A molecular dynamics simulation was employed to model the peptide's interactions with sodium dodecyl sulphate micelles, a widely used bacterial membrane-mimicking environment. Throughout the simulation, the peptide was found to maintain its α-helical conformation between residues Ile6-Ala26, while adopting a position parallel to the surface to micelle, which is energetically-favourable due to many hydrophobic and electrostatic contacts with the micelle.

scholarly journals Conformation and membrane interaction studies of the potent antimicrobial and anticancer peptide palustrin-Ca

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Patrick B. Timmons ◽  
Chandralal M. Hewage
Keyword(s):  
Sodium Dodecyl ◽  
Three Dimensional ◽  
Dynamics Simulation ◽  
Peptide Sequence ◽  
Helical Conformation ◽  
Dimensional Structure ◽  
Amino Acid Residues ◽  
Anticancer Activities ◽  
Anticancer Peptide ◽  
American Bullfrog

AbstractPalustrin-Ca (GFLDIIKDTGKEFAVKILNNLKCKLAGGCPP) is a host defence peptide with potent antimicrobial and anticancer activities, first isolated from the skin of the American bullfrog Lithobates catesbeianus. The peptide is 31 amino acid residues long, cationic and amphipathic. Two-dimensional NMR spectroscopy was employed to characterise its three-dimensional structure in a 50/50% water/2,2,2-trifluoroethanol-$$d_{3}$$ d 3 mixture. The structure is defined by an $$\alpha$$ α -helix that spans between Ile$$^{6}$$ 6 -Ala$$^{26}$$ 26 , and a cyclic disulfide-bridged domain at the C-terminal end of the peptide sequence, between residues 23 and 29. A molecular dynamics simulation was employed to model the peptide’s interactions with sodium dodecyl sulfate micelles, a widely used bacterial membrane-mimicking environment. Throughout the simulation, the peptide was found to maintain its $$\alpha$$ α -helical conformation between residues Ile$$^{6}$$ 6 -Ala$$^{26}$$ 26 , while adopting a position parallel to the surface to micelle, which is energetically-favourable due to many hydrophobic and electrostatic contacts with the micelle.

scholarly journals Discovery of Novel Inhibitors for Nek6 Protein through Homology Model Assisted Structure Based Virtual Screening and Molecular Docking Approaches

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
P. Srinivasan ◽  
P. Chella Perumal ◽  
A. Sudha
Keyword(s):  
Virtual Screening ◽  
Cell Cycle Progression ◽  
Three Dimensional ◽  
Homology Model ◽  
Mitotic Cell ◽  
Binding Pocket ◽  
Dynamics Simulation ◽  
Dimensional Structure ◽  
Amino Acid Residues ◽  
Relationship Of

Nek6 is a member of the NIMA (never in mitosis, gene A)-related serine/threonine kinase family that plays an important role in the initiation of mitotic cell cycle progression. This work is an attempt to emphasize the structural and functional relationship of Nek6 protein based on homology modeling and binding pocket analysis. The three-dimensional structure of Nek6 was constructed by molecular modeling studies and the best model was further assessed by PROCHECK, ProSA, and ERRAT plot in order to analyze the quality and consistency of generated model. The overall quality of computed model showed 87.4% amino acid residues under the favored region. A 3 ns molecular dynamics simulation confirmed that the structure was reliable and stable. Two lead compounds (Binding database ID: 15666, 18602) were retrieved through structure-based virtual screening and induced fit docking approaches as novel Nek6 inhibitors. Hence, we concluded that the potential compounds may act as new leads for Nek6 inhibitors designing.

scholarly journals Solution Structure of Acidocin B, a Circular Bacteriocin Produced by Lactobacillus acidophilus M46

2015 ◽  
Vol 81 (8) ◽  
pp. 2910-2918 ◽  
Author(s):  
Jeella Z. Acedo ◽  
Marco J. van Belkum ◽  
Christopher T. Lohans ◽  
Ryan T. McKay ◽  
Mark Miskolzie ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Lactobacillus Acidophilus ◽  
Solution Structure ◽  
Sequence Similarity ◽  
Sodium Dodecyl ◽  
Three Dimensional ◽  
Peptide Sequence ◽  
Dimensional Structure ◽  
Content Type ◽  
Circular Bacteriocin

ABSTRACTAcidocin B, a bacteriocin produced byLactobacillus acidophilusM46, was originally reported to be a linear peptide composed of 59 amino acid residues. However, its high sequence similarity to gassericin A, a circular bacteriocin fromLactobacillus gasseriLA39, suggested that acidocin B might be circular as well. Acidocin B was purified from culture supernatant by a series of hydrophobic interaction chromatographic steps. Its circular nature was ascertained by matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry and tandem mass spectrometry (MS/MS) sequencing. The peptide sequence was found to consist of 58 amino acids with a molecular mass of 5,621.5 Da. The sequence of the acidocin B biosynthetic gene cluster was also determined and showed high nucleotide sequence similarity to that of gassericin A. The nuclear magnetic resonance (NMR) solution structure of acidocin B in sodium dodecyl sulfate micelles was elucidated, revealing that it is composed of four α-helices of similar length that are folded to form a compact, globular bundle with a central pore. This is a three-dimensional structure for a member of subgroup II circular bacteriocins, which are classified based on their isoelectric points of ∼7 or lower. Comparison of acidocin B with carnocyclin A, a subgroup I circular bacteriocin with four α-helices and a pI of 10, revealed differences in the overall folding. The observed variations could be attributed to inherent diversity in their physical properties, which also required the use of different solvent systems for three-dimensional structural elucidation.

scholarly journals Functional Analysis of the Mycobacterium tuberculosis FAD-Dependent Thymidylate Synthase, ThyX, Reveals New Amino Acid Residues Contributing to an Extended ThyX Motif

2008 ◽  
Vol 190 (6) ◽  
pp. 2056-2064 ◽  
Author(s):  
Jonathan E. Ulmer ◽  
Yap Boum ◽  
Christopher D. Thouvenel ◽  
Hannu Myllykallio ◽  
Carol Hopkins Sibley
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Thymidylate Synthase ◽  
Three Dimensional ◽  
Pyrimidine Ring ◽  
Dimensional Structure ◽  
Directed Mutagenesis ◽  
Catalytic Residue ◽  
Amino Acid Residues ◽  
Insight Into

ABSTRACT A novel FAD-dependent thymidylate synthase, ThyX, is present in a variety of eubacteria and archaea, including the mycobacteria. A short motif found in all thyX genes, RHRX7-8S, has been identified. The three-dimensional structure of the Mycobacterium tuberculosis ThyX enzyme has been solved. Building upon this information, we used directed mutagenesis to produce 67 mutants of the M. tuberculosis thyX gene. Each enzyme was assayed to determine its ability to complement the defect in thymidine biosynthesis in a ΔthyA strain of Escherichia coli. Enzymes from selected strains were then tested in vitro for their ability to catalyze the oxidation of NADPH and the release of a proton from position 5 of the pyrimidine ring of dUMP. The results defined an extended motif of amino acids essential to enzyme activity in M. tuberculosis (Y44X24 H69X25R95HRX7 S105XRYX90R199 [with the underlined histidine acting as the catalytic residue and the underlined serine as the nucleophile]) and provided insight into the ThyX reaction mechanism. ThyX is found in a variety of bacterial pathogens but is absent in humans, which depend upon an unrelated thymidylate synthase, ThyA. Therefore, ThyX is a potential target for development of antibacterial drugs.

scholarly journals Generalized predictive model of estimation of inhibition of muscarinic receptors M1-M5

2020 ◽  
Vol 3 (3) ◽  
pp. e00129
Author(s):  
A.V. Mikurova ◽  
V.S. Skvortsov ◽  
V.V. Grigoryev
Keyword(s):  
Predictive Model ◽  
Muscarinic Receptors ◽  
Three Dimensional ◽  
Dynamics Simulation ◽  
Dimensional Structure ◽  
Regression Equations ◽  
Energy Characteristics ◽  
Value Prediction ◽  
M3 Receptor ◽  
The Mean

A general predictive model for assessing the inhibition constant (K<sub>i</sub>) value of human acetylcholine muscarinic receptors M1-M5 by potential ligands has been constructed. We used information on the three-dimensional structure of human M1, M2, M4, and M5 receptors, as well as a model of the M3 receptor constructed according to homology based on the structure of the rat M3 receptor. A set of complexes of known inhibitors with the target receptor constructed by means of molecular docking, was selected using an additional option: the coincidence of the spatial position of 4 pharmacophore points of a tested inhibitor and tiotropium, for which the position in the crystal structure was known. For five types of M receptors 199 complexes with known K<sub>i</sub> values were selected. Based on the data obtained during molecular dynamics simulation of these complexes by means of the MM-PBSA/MM-GBSA methods, their energy characteristics were calculated. They were used as independent variables in linear regression equations for pK<sub>i</sub> value prediction. The R<sup>2</sup> prediction for the generalized equation was 0.7, and the mean prediction error was 0.55 logarithmic units with a range for pK<sub>i</sub>=4.7.

scholarly journals Evolutionary conservation of the intrinsic disorder-based Radical-Induced Cell Death1 hub interactome

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Lise Friis Christensen ◽  
Lasse Staby ◽  
Katrine Bugge ◽  
Charlotte O’Shea ◽  
Birthe B. Kragelund ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Stress Responses ◽  
Plant Stress ◽  
Three Dimensional ◽  
Intrinsic Disorder ◽  
Dimensional Structure ◽  
Linear Motif ◽  
Intrinsically Disordered ◽  
Helix Formation ◽  
Α Helix

AbstractRadical-Induced Cell Death1 (RCD1) functions as a cellular hub interacting with intrinsically disordered transcription factor regions, which lack a well-defined three-dimensional structure, to regulate plant stress. Here, we address the molecular evolution of the RCD1-interactome. Using bioinformatics, its history was traced back more than 480 million years to the emergence of land plants with the RCD1-binding short linear motif (SLiM) identified from mosses to flowering plants. SLiM variants were biophysically verified to be functional and to depend on the same RCD1 residues as the DREB2A transcription factor. Based on this, numerous additional members may be assigned to the RCD1-interactome. Conservation was further strengthened by similar intrinsic disorder profiles of the transcription factor homologs. The unique structural plasticity of the RCD1-interactome, with RCD1-binding induced α-helix formation in DREB2A, but not detectable in ANAC046 or ANAC013, is apparently conserved. Thermodynamic analysis also indicated conservation with interchangeability between Arabidopsis and soybean RCD1 and DREB2A, although with fine-tuned co-evolved binding interfaces. Interruption of conservation was observed, as moss DREB2 lacked the SLiM, likely reflecting differences in plant stress responses. This whole-interactome study uncovers principles of the evolution of SLiM:hub-interactions, such as conservation of α-helix propensities, which may be paradigmatic for disorder-based interactomes in eukaryotes.

scholarly journals Ribokinase fromLeishmania donovani: purification, characterization and X-ray crystallographic analysis

2018 ◽  
Vol 74 (2) ◽  
pp. 99-104 ◽  
Author(s):  
Santhosh Gatreddi ◽  
Sayanna Are ◽  
Insaf Ahmed Qureshi
Keyword(s):  
Functional Characterization ◽  
Three Dimensional ◽  
Protozoan Parasite ◽  
Crystallographic Analysis ◽  
Size Exclusion ◽  
Dimensional Structure ◽  
Diffusion Method ◽  
Gene Encoding ◽  
Cell Parameters ◽  
Α Helix

Leishmaniais an auxotrophic protozoan parasite which acquires D-ribose by transporting it from the host cell and also by the hydrolysis of nucleosides. The enzyme ribokinase (RK) catalyzes the first step of ribose metabolism by phosphorylating D-ribose using ATP to produce D-ribose-5-phosphate. To understand its structure and function, the gene encoding RK fromL. donovaniwas cloned, expressed and purified using affinity and size-exclusion chromatography. Circular-dichroism spectroscopy of the purified protein showed comparatively more α-helix in the secondary-structure content, and thermal unfolding revealed theTmto be 317.2 K. Kinetic parameters were obtained by functional characterization ofL. donovaniRK, and theKmvalues for ribose and ATP were found to be 296 ± 36 and 116 ± 9.0 µM, respectively. Crystals obtained by the hanging-drop vapour-diffusion method diffracted to 1.95 Å resolution and belonged to the hexagonal space groupP61, with unit-cell parametersa=b= 100.25,c= 126.77 Å. Analysis of the crystal content indicated the presence of two protomers in the asymmetric unit, with a Matthews coefficient (VM) of 2.45 Å3 Da−1and 49.8% solvent content. Further study revealed that human counterpart of this protein could be used as a template to determine the first three-dimensional structure of the RK from trypanosomatid parasites.

Characteristics of Two Forms of α-Amylases and Structural Implication

1999 ◽  
Vol 65 (10) ◽  
pp. 4652-4658 ◽  
Author(s):  
Kohji Ohdan ◽  
Takashi Kuriki ◽  
Hiroki Kaneko ◽  
Jiro Shimada ◽  
Toshikazu Takada ◽  
...  
Keyword(s):  
Amino Acid ◽  
Three Dimensional ◽  
Amino Acid Sequences ◽  
Dimensional Structure ◽  
Amino Acid Residues ◽  
Amylase Gene ◽  
Raw Starch ◽  
Raw Starch Binding ◽  
Terminal Amino ◽  
Carboxyl Terminal

ABSTRACT Complete (Ba-L) and truncated (Ba-S) forms of α-amylases fromBacillus subtilis X-23 were purified, and the amino- and carboxyl-terminal amino acid sequences of Ba-L and Ba-S were determined. The amino acid sequence deduced from the nucleotide sequence of the α-amylase gene indicated that Ba-S was produced from Ba-L by truncation of the 186 amino acid residues at the carboxyl-terminal region. The results of genomic Southern analysis and Western analysis suggested that the two enzymes originated from the same α-amylase gene and that truncation of Ba-L to Ba-S occurred during the cultivation of B. subtilis X-23 cells. Although the primary structure of Ba-S was approximately 28% shorter than that of Ba-L, the two enzyme forms had the same enzymatic characteristics (molar catalytic activity, amylolytic pattern, transglycosylation ability, effect of pH on stability and activity, optimum temperature, and raw starch-binding ability), except that the thermal stability of Ba-S was higher than that of Ba-L. An analysis of the secondary structure as well as the predicted three-dimensional structure of Ba-S showed that Ba-S retained all of the necessary domains (domains A, B, and C) which were most likely to be required for functionality as α-amylase.

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