1
|
Grabeck J, Mayer J, Miltz A, Casoria M, Quagliata M, Meinberger D, Klatt AR, Wielert I, Maier B, Papini AM, Neundorf I. Triazole-Bridged Peptides with Enhanced Antimicrobial Activity and Potency against Pathogenic Bacteria. ACS Infect Dis 2024. [PMID: 38885643 DOI: 10.1021/acsinfecdis.4c00078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/20/2024]
Abstract
There are still no linear antimicrobial peptides (AMPs) available as a treatment option against bacterial infections. This is caused by several drawbacks that come with AMPs such as limited proteolytic stability and low selectivity against human cells. In this work, we screened a small library of rationally designed new peptides based on the cell-penetrating peptide sC18* toward their antimicrobial activity. We identified several effective novel AMPs and chose one out of this group to further increase its potency. Therefore, we introduced a triazole bridge at different positions to provide a preformed helical structure, assuming that this modification would improve (i) proteolytic stability and (ii) membrane activity. Indeed, placing the triazole bridge within the hydrophilic part of the linear analogue highly increased membrane activity as well as stability against enzymatic digestion. The new peptides, 8A and 8B, demonstrated high activity against several bacterial species tested including pathogenic N. gonorrhoeae and methicillin-resistant S. aureus. Since they exhibited significantly good tolerability against human fibroblast and blood cells, these novel peptides offer true alternatives for future clinical applications and are worth studying in more detail.
Collapse
Affiliation(s)
- Joshua Grabeck
- University of Cologne, Faculty of Mathematics and Natural Sciences, Department of Chemistry, Institute of Biochemistry, Zuelpicher Str. 47a, 50674 Cologne, Germany
| | - Jacob Mayer
- University of Cologne, Faculty of Mathematics and Natural Sciences, Department of Chemistry, Institute of Biochemistry, Zuelpicher Str. 47a, 50674 Cologne, Germany
| | - Axel Miltz
- University of Cologne, Faculty of Mathematics and Natural Sciences, Department of Chemistry, Institute of Biochemistry, Zuelpicher Str. 47a, 50674 Cologne, Germany
| | - Michele Casoria
- Interdepartmental Research Unit of Peptide and Protein Chemistry and Biology, Department of Chemistry "Ugo Schiff", University of Florence, Via della Lastruccia 13, 50019 Sesto Fiorentino, Italy
| | - Michael Quagliata
- Interdepartmental Research Unit of Peptide and Protein Chemistry and Biology, Department of Chemistry "Ugo Schiff", University of Florence, Via della Lastruccia 13, 50019 Sesto Fiorentino, Italy
| | - Denise Meinberger
- University of Cologne, Faculty of Medicine, Institute for Clinical Chemistry, Kerpener Str. 62, 50937 Cologne, Germany
| | - Andreas R Klatt
- University of Cologne, Faculty of Medicine, Institute for Clinical Chemistry, Kerpener Str. 62, 50937 Cologne, Germany
| | - Isabelle Wielert
- University of Cologne, Faculty of Mathematics and Natural Sciences, Department of Physics, Institute for Biological Physics, Zuelpicher Str. 47a, 50674 Cologne, Germany
| | - Berenike Maier
- University of Cologne, Faculty of Mathematics and Natural Sciences, Department of Physics, Institute for Biological Physics, Zuelpicher Str. 47a, 50674 Cologne, Germany
| | - Anna Maria Papini
- Interdepartmental Research Unit of Peptide and Protein Chemistry and Biology, Department of Chemistry "Ugo Schiff", University of Florence, Via della Lastruccia 13, 50019 Sesto Fiorentino, Italy
| | - Ines Neundorf
- University of Cologne, Faculty of Mathematics and Natural Sciences, Department of Chemistry, Institute of Biochemistry, Zuelpicher Str. 47a, 50674 Cologne, Germany
| |
Collapse
|
2
|
Peggion C, Panetta V, Lastella L, Formaggio F, Ricci A, Oancea S, Hilma G, Biondi B. Relevance of amphiphilicity and helicity on the antibacterial action of a histatin 5-derived peptide. J Pept Sci 2024:e3609. [PMID: 38676397 DOI: 10.1002/psc.3609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 04/09/2024] [Accepted: 04/10/2024] [Indexed: 04/28/2024]
Abstract
Peptide dhvar4, derived from the active domain of our salivary peptide histatin 5, bears a Phe residue in the middle of its hydrophilic face when folded into an α-helix. We then synthesized an analog with this Phe replaced by Lys and two analogs preserving Phe but bearing two and three α-aminoisobutyric acid (Aib) residues to stabilize the helical structure. The aim of this design was to verify which of the two features is more favorable to the biological activity. We performed a conformational study by means of circular dichroism and nuclear magnetic resonance, made antibacterial tests, and assessed the stability of the peptides in human serum. We observed that amphiphilicity is more important than helix stability, provided a peptide can adopt a helical conformation in a membrane-mimetic environment.
Collapse
Affiliation(s)
| | - Valeria Panetta
- Department of Chemistry, University of Padova, Padova, Italy
| | - Luana Lastella
- Department of Chemistry, University of Padova, Padova, Italy
| | - Fernando Formaggio
- Department of Chemistry, University of Padova, Padova, Italy
- Institute of Biomolecular Chemistry, Padova Unit, CNR, Padova, Italy
| | | | - Simona Oancea
- Department of Agricultural Sciences and Food Engineering, "Lucian Blaga" University of Sibiu, Sibiu, Romania
| | - Geta Hilma
- Public Health Directorate, Sibiu, Romania
| | - Barbara Biondi
- Institute of Biomolecular Chemistry, Padova Unit, CNR, Padova, Italy
| |
Collapse
|
3
|
Klußmann M, Stillger K, Ruppel M, Sticker CL, Neundorf I. Investigating the impact of thiol reactivity and disulfide formation on cellular uptake of cell-permeable peptides. J Pept Sci 2024:e3604. [PMID: 38651525 DOI: 10.1002/psc.3604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 03/20/2024] [Accepted: 03/24/2024] [Indexed: 04/25/2024]
Abstract
Cell-penetrating peptides (CPPs) have been explored as versatile tools to transport various molecules into cells. The uptake mechanism of CPPs is still not clearly understood and most probably depends on several factors like the nature of the CPP itself, the attached cargo, the investigated cell system, and other experimental conditions, such as temperature and concentration. One of the first steps of internalization involves the interaction of CPPs with negatively charged molecules present at the outer layer of the cell membrane. Recently, thiol-mediated uptake has been found to support the effective translocation of sulfhydryl-bearing substances that would actually not be cell-permeable. Within this work, we aimed to understand the relevance of thiol reactivity for the uptake mechanism of cysteine-containing CPPs that we have developed previously in our group. Therefore, we compared the two peptides, sC18-Cys and CaaX-1, in their single reduced and dimeric disulfide versions. Cytotoxicity, intracellular accumulation, and impact on the internalization process of the disulfides were investigated in HeLa cells. Both disulfide CPPs demonstrated significantly stronger cytotoxic effects and membrane activity compared with their reduced counterparts. Notably, thiol-mediated uptake could be excluded as a main driver for translocation, showing that peptides like CaaX-1 are most likely taken up by other mechanisms.
Collapse
Affiliation(s)
- Merlin Klußmann
- Institute for Biochemistry, University of Cologne, Cologne, Germany
| | | | - Melina Ruppel
- Institute for Biochemistry, University of Cologne, Cologne, Germany
| | | | - Ines Neundorf
- Institute for Biochemistry, University of Cologne, Cologne, Germany
| |
Collapse
|
4
|
Zavrtanik U, Lah J, Hadži S. Estimation of Peptide Helicity from Circular Dichroism Using the Ensemble Model. J Phys Chem B 2024; 128:2652-2663. [PMID: 38470351 PMCID: PMC10961730 DOI: 10.1021/acs.jpcb.3c07511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 02/27/2024] [Accepted: 02/28/2024] [Indexed: 03/13/2024]
Abstract
An established method for the quantitation of the helix content in peptides using circular dichroism (CD) relies on the linear spectroscopic model. This model assumes an average value of the helix-length correction for all peptide conformers, irrespective of the length of the helical segment. Here we assess the validity of this approximation and introduce a more physically realistic ensemble-based analysis of the CD signal in which the length correction is assigned specifically to each ensemble conformer. We demonstrate that the linear model underestimates peptide helicity, with the difference depending on the ensemble composition. We developed a computer program that implements the ensemble model to estimate the peptide helicity. Using this model and the CD data set covering a broad range of helicities, we recalibrate CD baseline parameters and redetermine helix-coil parameters for the alanine-rich peptide. We show that the ensemble model leverages small differences in signal between conformers to extract more information from the experimental data, enabling the determination of several poorly defined quantities, such as the nucleation constant and heat capacity change associated with helix folding. Overall, the presented ensemble-based treatment of the CD signal, together with the recalibrated values of the spectroscopic baseline parameters, provides a coherent framework for the analysis of the peptide helix content.
Collapse
Affiliation(s)
- Uroš Zavrtanik
- Department of Physical Chemistry,
Faculty of Chemistry and Chemical Technology, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Jurij Lah
- Department of Physical Chemistry,
Faculty of Chemistry and Chemical Technology, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - San Hadži
- Department of Physical Chemistry,
Faculty of Chemistry and Chemical Technology, University of Ljubljana, 1000 Ljubljana, Slovenia
| |
Collapse
|
5
|
Lee PY, Singh O, Nanajkar N, Bermudez H, Matysiak S. Opposing roles of organic salts on mini-protein structure. Phys Chem Chem Phys 2024; 26:8973-8981. [PMID: 38436427 DOI: 10.1039/d3cp05607d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2024]
Abstract
We investigated the effects of 1-ethyl-3-methylimidazolium chloride ([EMIM][Cl]) and choline chloride ([Chol][Cl]) on the local environment and conformational landscapes of Trp-cage and Trpzip4 mini-proteins using experimental and computational approaches. Fluorescence experiments and computational simulations revealed distinct behaviors of the mini-proteins in the presence of these organic salts. [EMIM][Cl] showed a strong interaction with Trp-cage, leading to fluorescence quenching and destabilization of its native structural interactions. Conversely, [Chol][Cl] had a negligible impact on Trp-cage fluorescence at low concentrations but increased it at high concentrations, indicating a stabilizing role. Computational simulations elucidated that [EMIM][Cl] disrupted the hydrophobic core packing and decreased proline-aromatic residue contacts in Trp-cage, resulting in a more exposed environment for Trp residues. In contrast, [Chol][Cl] subtly influenced the hydrophobic core packing, creating a hydrophobic environment near the tryptophan residues. Circular dichroism experiments revealed that [Chol][Cl] stabilized the secondary structure of both mini-proteins, although computational simulations did not show significant changes in secondary content at the explored concentrations. The simulations also demonstrated a more rugged free energy landscape for Trp-cage and Trpzip4 in [EMIM][Cl], suggesting destabilization of the tertiary structure for Trp-cage and secondary structure for Trpzip4. Similar fluorescence trends were observed for Trpzip4, with [EMIM][Cl] quenching fluorescence and exhibiting stronger interaction, while [Chol][Cl] increased the fluorescence at high concentrations. These findings highlight the interplay between [EMIM][Cl] and [Chol][Cl] with the mini-proteins and provide a detailed molecular-level understanding of how these organic salts impact the nearby surroundings and structural variations. Understanding such interactions is valuable for diverse applications, from biochemistry to materials science.
Collapse
Affiliation(s)
- Pei-Yin Lee
- Chemical Physics Program, Institute for Physical Science and Technology, University of Maryland, College Park, USA
| | - Onkar Singh
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, MA, USA.
| | - Neha Nanajkar
- Department of Biology, University of Maryland, College Park, USA
| | - Harry Bermudez
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, MA, USA.
| | - Silvina Matysiak
- Fischell Department of Bioengineering, University of Maryland, College Park, USA.
| |
Collapse
|
6
|
Biondi B, de Pascale L, Mardirossian M, Di Stasi A, Favaro M, Scocchi M, Peggion C. Structural and biological characterization of shortened derivatives of the cathelicidin PMAP-36. Sci Rep 2023; 13:15132. [PMID: 37704689 PMCID: PMC10499915 DOI: 10.1038/s41598-023-41945-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 09/04/2023] [Indexed: 09/15/2023] Open
Abstract
Cathelicidins, a family of host defence peptides in vertebrates, play an important role in the innate immune response, exhibiting antimicrobial activity against many bacteria, as well as viruses and fungi. This work describes the design and synthesis of shortened analogues of porcine cathelicidin PMAP-36, which contain structural changes to improve the pharmacokinetic properties. In particular, 20-mers based on PMAP-36 (residues 12-31) and 13-mers (residues 12-24) with modification of amino acid residues at critical positions and introduction of lipid moieties of different lengths were studied to identify the physical parameters, including hydrophobicity, charge, and helical structure, required to optimise their antibacterial activity. Extensive conformational analysis, performed by CD and NMR, revealed that the substitution of Pro25-Pro26 with Ala25-Lys26 increased the α-helix content of the 20-mer peptides, resulting in broad-spectrum antibacterial activity against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Staphylococcus epidermidis strains. Interestingly, shortening to just 13 residues resulted in only a slight decrease in antibacterial activity. Furthermore, two sequences, a 13-mer and a 20-mer, did not show cytotoxicity against HaCat cells up to 64 µM, indicating that both derivatives are not only effective but also selective antimicrobial peptides. In the short peptide, the introduction of the helicogenic α-aminoisobutyric acid forced the helix toward a prevailing 310 structure, allowing the antimicrobial activity to be maintained. Preliminary tests of resistance to Ser protease chymotrypsin indicated that this modification resulted in a peptide with an increased in vivo lifespan. Thus, some of the PMAP-36 derivatives studied in this work show a good balance between chain length, antibacterial activity, and selectivity, so they represent a good starting point for the development of even more effective and proteolysis-resistant active peptides.
Collapse
Affiliation(s)
- Barbara Biondi
- Institute of Biomolecular Chemistry, CNR, Padova Unit, Padova, Italy
| | - Luigi de Pascale
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | | | - Adriana Di Stasi
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | - Matteo Favaro
- Department of Chemical Sciences, University of Padova, Padova, Italy
| | - Marco Scocchi
- Department of Life Sciences, University of Trieste, Trieste, Italy.
| | - Cristina Peggion
- Institute of Biomolecular Chemistry, CNR, Padova Unit, Padova, Italy.
- Department of Chemical Sciences, University of Padova, Padova, Italy.
| |
Collapse
|
7
|
Sukumaran S, Tan M, Ben-Uliel SF, Zhang H, De Zotti M, Chua MS, So SK, Qvit N. Rational design, synthesis and structural characterization of peptides and peptidomimetics to target Hsp90/Cdc37 interaction for treating hepatocellular carcinoma. Comput Struct Biotechnol J 2023; 21:3159-3172. [PMID: 37304004 PMCID: PMC10250827 DOI: 10.1016/j.csbj.2023.05.023] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 05/23/2023] [Accepted: 05/23/2023] [Indexed: 06/13/2023] Open
Abstract
Heat shock protein 90 (Hsp90) and cell division cycle 37 (Cdc37) work together as a molecular chaperone complex to regulate the activity of a multitude of client protein kinases. These kinases belong to a wide array of intracellular signaling networks that mediate multiple cellular processes including proliferation. As a result, Hsp90 and Cdc37 represent innovative therapeutic targets in various cancers (such as leukemia, multiple myeloma, and hepatocellular carcinoma (HCC)) in which their expression levels are elevated. Conventional small molecule Hsp90 inhibitors act by blocking the conserved adenosine triphosphate (ATP) binding site. However, by targeting less conserved sites in a more specific manner, peptides and peptidomimetics (modified peptides) hold potential as more efficacious and less toxic alternatives to the conventional small molecule inhibitors. Using a rational approach, we herein developed bioactive peptides targeting Hsp90/Cdc37 interaction. A six amino acid linear peptide derived from Cdc37, KTGDEK, was designed to target Hsp90. We used in silico computational docking to first define its mode of interaction, and binding orientation, and then conjugated the peptide with a cell penetrating peptide, TAT, and a fluorescent dye to confirm its ability to colocalize with Hsp90 in HCC cells. Based on the parent linear sequence, we developed a peptidomimetics library of pre-cyclic and cyclic derivatives. These peptidomimetics were evaluated for their binding affinity to Hsp90, and bioactivity in HCC cell lines. Among them, a pre-cyclic peptidomimetic demonstrates high binding affinity and bioactivity in HCC cells, causing reduced cell proliferation that is associated with induction of cell apoptosis, and down-regulation of phosphorylated MEK1/2. Overall, this generalized approach of rational design, structural optimization, and cellular validation of 'drug-like' peptidomimetics against Hsp90/Cdc37 offers a feasible and promising way to design novel therapeutic agents for malignancies and other diseases that are dependent on this molecular chaperone complex.
Collapse
Affiliation(s)
- Surya Sukumaran
- The Azrieli Faculty of Medicine in the Galilee, Bar-Ilan University, Henrietta Szold St. 8, Safed 1311502, Israel
| | - Mingdian Tan
- Asian Liver Center, Department of Surgery, Stanford University School of Medicine, 1201 Welch Road, Palo Alto, CA 94305, USA
| | - Shulamit Fluss Ben-Uliel
- The Azrieli Faculty of Medicine in the Galilee, Bar-Ilan University, Henrietta Szold St. 8, Safed 1311502, Israel
| | - Hui Zhang
- Asian Liver Center, Department of Surgery, Stanford University School of Medicine, 1201 Welch Road, Palo Alto, CA 94305, USA
| | - Marta De Zotti
- Department of Chemistry, University of Padova, Via Marzolo 1, 35131 Padova, Italy
| | - Mei-Sze Chua
- Asian Liver Center, Department of Surgery, Stanford University School of Medicine, 1201 Welch Road, Palo Alto, CA 94305, USA
| | - Samuel K. So
- Asian Liver Center, Department of Surgery, Stanford University School of Medicine, 1201 Welch Road, Palo Alto, CA 94305, USA
| | - Nir Qvit
- The Azrieli Faculty of Medicine in the Galilee, Bar-Ilan University, Henrietta Szold St. 8, Safed 1311502, Israel
| |
Collapse
|
8
|
Anticancer and Targeting Activity of Phytopharmaceutical Structural Analogs of a Natural Peptide from Trichoderma longibrachiatum and Related Peptide-Decorated Gold Nanoparticles. Int J Mol Sci 2023; 24:ijms24065537. [PMID: 36982610 PMCID: PMC10057332 DOI: 10.3390/ijms24065537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 03/08/2023] [Accepted: 03/13/2023] [Indexed: 03/18/2023] Open
Abstract
In the large field of bioactive peptides, peptaibols represent a unique class of compounds. They are membrane-active peptides, produced by fungi of the genus Trichoderma and known to elicit plant defenses. Among the short-length peptaibols, trichogin GA IV is nonhemolytic, proteolysis-resistant, antibacterial, and cytotoxic. Several trichogin analogs are endowed with potent activity against phytopathogens, thus representing a sustainable alternative to copper for plant protection. In this work, we tested the activity of trichogin analogs against a breast cancer cell line and a normal cell line of the same derivation. Lys-containing trichogins showed an IC50 below 12 µM, a peptide concentration not significantly affecting the viability of normal cells. Two analogs were found to be membrane-active but noncytotoxic. They were anchored to gold nanoparticles (GNPs) and further investigated for their ability to act as targeting agents. GNP uptake by cancer cells increased with peptide decoration, while it decreased in the corresponding normal epithelial cells. This work highlights the promising biological properties of peptaibol analogs in the field of cancer therapy either as cytotoxic molecules or as active targeting agents in drug delivery.
Collapse
|
9
|
Morbiato L, Haneen DSA, Formaggio F, De Zotti M. Total synthesis of the natural, medium-length, peptaibol pentadecaibin and study of the chemical features responsible for its membrane activity. J Pept Sci 2023:e3479. [PMID: 36652104 DOI: 10.1002/psc.3479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 01/11/2023] [Accepted: 01/13/2023] [Indexed: 01/19/2023]
Abstract
Peptaibols are naturally occurring, antimicrobial peptides endowed with well-defined helical conformations and resistance to proteolysis. Both features stem from the presence in their sequence of several, Cα -tetrasubstituted, α-aminoisobutyric acid (Aib) residues. Peptaibols interact with biological membranes, usually causing their leakage. All of the peptaibol-membrane interaction mechanisms proposed so far begin with peptide aggregation or accumulation. The long-length alamethicin, the most studied peptaibol, acts by forming pores in the membranes. Conversely, the carpet mechanism has been claimed for short-length peptaibols, such as trichogin. The mechanism of medium-length peptaibols is far less studied, and this is partly due to the difficulties of their synthesis. They are believed to perturb membrane permeability in different ways, depending on the membrane properties. The present work focuses on pentadecaibin, a recently discovered, medium-length peptaibol. In contrast to the majority of its family members, its sequence does not comprise hydroxyprolines or prolines, and its helix is not kinked. A reliable and effective synthesis procedure is described that allowed us to produce also two shorter analogs. By a combination of techniques, we were able to establish a 3D-structure-activity relationship. In particular, the membrane activity of pentadecaibin heavily depends on the presence of three consecutive Aib residues that are responsible for the clear, albeit modest, amphiphilic character of its helix. The shortest analog, devoid of two of these three Aib residues, preserves a well-defined helical conformation, but not its amphipathicity, and loses almost completely the ability to cause membrane leakage. We conclude that pentadecaibin amphiphilicity is probably needed for the peptide ability to perturb model membranes.
Collapse
Affiliation(s)
- Laura Morbiato
- Department of Chemical Sciences, University of Padova, Padova, Italy
| | - David S A Haneen
- Chemistry Department, Faculty of Science, Ain Shams University, Cairo, Abbassia, 11566, Egypt
| | - Fernando Formaggio
- Department of Chemical Sciences, University of Padova, Padova, Italy.,Padova Unit, CNR Institute of Biomolecular Chemistry, University of Padova, Padova, Italy
| | - Marta De Zotti
- Department of Chemical Sciences, University of Padova, Padova, Italy.,Padova Unit, CNR Institute of Biomolecular Chemistry, University of Padova, Padova, Italy
| |
Collapse
|
10
|
Monitoring the effect of SDS on the solvation dynamics and structural conformation of β-casein. J CHEM SCI 2022. [DOI: 10.1007/s12039-022-02092-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
11
|
Shi XJ, Liu Z, Xie YC, Xu M, He XH. Homopolypeptide Vesicles Triggered by Side-Chain Hydration. CHINESE JOURNAL OF POLYMER SCIENCE 2022. [DOI: 10.1007/s10118-022-2784-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
12
|
Biondi B, Syryamina VN, Rocchio G, Barbon A, Formaggio F, Toniolo C, Raap J, Dzuba SA. Is Cys(MTSL) the Best α-Amino Acid Residue to Electron Spin Labeling of Synthetically Accessible Peptide Molecules with Nitroxides? ACS OMEGA 2022; 7:5154-5165. [PMID: 35187331 PMCID: PMC8851612 DOI: 10.1021/acsomega.1c06227] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 12/27/2021] [Indexed: 06/14/2023]
Abstract
Electron paramagnetic resonance spectroscopy, particularly its pulse technique double electron-electron resonance (DEER) (also termed PELDOR), is rapidly becoming an extremely useful tool for the experimental determination of side chain-to-side chain distances between free radicals in molecules fundamental for life, such as polypeptides. Among appropriate probes, the most popular are undoubtedly nitroxide electron spin labels. In this context, suitable biosynthetically derived, helical regions of proteins, along with synthetic peptides with amphiphilic properties and antibacterial activities, are the most extensively investigated compounds. A strict requirement for a precise distance measurement has been identified in a minimal dynamic flexibility of the two nitroxide-bearing α-amino acid side chains. To this end, in this study, we have experimentally compared in detail the side-chain mobility properties of the two currently most widely utilized residues, namely, Cys(MTSL) and 2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid (TOAC). In particular, two double-labeled, chemically synthesized 20-mer peptide molecules have been adopted as appropriate templates for our investigation on the determination of the model intramolecular separations. These double-Cys(MTSL) and double-TOAC compounds are both analogues of the almost completely rigid backbone peptide ruler which we have envisaged and 3D structurally analyzed as our original, unlabeled compound. Here, we have clearly found that the TOAC side-chain labels are largely more 3D structurally restricted than the MTSL labels. From this result, we conclude that the TOAC residue offers more precise information than the Cys(MTSL) residue on the side chain-to-side chain distance distribution in synthetically accessible peptide molecules.
Collapse
Affiliation(s)
- Barbara Biondi
- Institute
of Biomolecular Chemistry, Padova Unit, CNR, 35131 Padova, Italy
| | - Victoria N. Syryamina
- Institute
of Chemical Kinetics and Combustion, 630090 Novosibirsk, Russian Federation
| | - Gabriele Rocchio
- Department
of Chemical Sciences, University of Padova, 35131 Padova, Italy
| | - Antonio Barbon
- Department
of Chemical Sciences, University of Padova, 35131 Padova, Italy
| | - Fernando Formaggio
- Institute
of Biomolecular Chemistry, Padova Unit, CNR, 35131 Padova, Italy
- Department
of Chemical Sciences, University of Padova, 35131 Padova, Italy
| | - Claudio Toniolo
- Institute
of Biomolecular Chemistry, Padova Unit, CNR, 35131 Padova, Italy
- Department
of Chemical Sciences, University of Padova, 35131 Padova, Italy
| | - Jan Raap
- Leiden
Institute of Chemistry, Gorlaeus Laboratories,
Leiden University, 2300 RA Leiden, The Netherlands
| | - Sergei A. Dzuba
- Institute
of Chemical Kinetics and Combustion, 630090 Novosibirsk, Russian Federation
- Department
of Physics, Novosibirsk State University, 630090 Novosibirsk, Russian Federation
| |
Collapse
|
13
|
Banerjee R, Sheet T, Banerjee S, Biondi B, Formaggio F, Toniolo C, Peggion C. C α-Methyl-l-valine: A Preferential Choice over α-Aminoisobutyric Acid for Designing Right-Handed α-Helical Scaffolds. Biochemistry 2021; 60:2704-2714. [PMID: 34463474 DOI: 10.1021/acs.biochem.1c00340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In synthetic peptides containing Gly and coded α-amino acids, one of the most common practices to enhance their helical extent is to incorporate a large number of l-Ala residues along with noncoded, strongly foldameric α-aminoisobutyric acid (Aib) units. Earlier studies have established that Aib-based peptides, with propensity for both the 310- and α-helices, have a tendency to form ordered three-dimensional structure that is much stronger than that exhibited by their l-Ala rich counterparts. However, the achiral nature of Aib induces an inherent, equal preference for the right- and left-handed helical conformations as found in Aib homopeptide stretches. This property poses challenges in the analysis of a model peptide helical conformation based on chirospectroscopic techniques like electronic circular dichroism (ECD), a very important tool for assigning secondary structures. To overcome such ambiguity, we have synthesized and investigated a thermally stable 14-mer peptide in which each of the Aib residues of our previously designed and reported analogue ABGY (where B stands for Aib) is replaced by Cα-methyl-l-valine (L-AMV). Analysis of the results described here from complementary ECD and 1H nuclear magnetic resonance spectroscopic techniques in a variety of environments firmly establishes that the L-AMV-containing peptide exhibits a significantly stronger preference compared to that of its Aib parent in terms of conferring α-helical character. Furthermore, being a chiral α-amino acid, L-AMV shows an intrinsic, extremely strong bias for a quite specific (right-handed) screw sense. These findings emphasize the relevance of L-AMV as a more appropriate unit for the design of right-handed α-helical peptide models that may be utilized as conformationally constrained scaffolds.
Collapse
Affiliation(s)
| | | | | | - Barbara Biondi
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy.,Institute of Biomolecular Chemistry, Padova Unit, CNR, 35131 Padova, Italy
| | - Fernando Formaggio
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy.,Institute of Biomolecular Chemistry, Padova Unit, CNR, 35131 Padova, Italy
| | - Claudio Toniolo
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy.,Institute of Biomolecular Chemistry, Padova Unit, CNR, 35131 Padova, Italy
| | - Cristina Peggion
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy.,Institute of Biomolecular Chemistry, Padova Unit, CNR, 35131 Padova, Italy
| |
Collapse
|
14
|
Abstract
Aberrant Ras signaling is linked to a wide spectrum of hyperproliferative diseases, and components of the signaling pathway, including Ras, have been the subject of intense and ongoing drug discovery efforts. The cellular activity of Ras is modulated by its association with the guanine nucleotide exchange factor Son of sevenless (Sos), and the high-resolution crystal structure of the Ras-Sos complex provides a basis for the rational design of orthosteric Ras ligands. We constructed a synthetic Sos protein mimic that engages the wild-type and oncogenic forms of nucleotide-bound Ras and modulates downstream kinase signaling. The Sos mimic was designed to capture the conformation of the Sos helix-loop-helix motif that makes critical contacts with Ras in its switch region. Chemoproteomic studies illustrate that the proteomimetic engages Ras and other cellular GTPases. The synthetic proteomimetic resists proteolytic degradation and enters cells through macropinocytosis. As such, it is selectively toxic to cancer cells with up-regulated macropinocytosis, including those that feature oncogenic Ras mutations.
Collapse
|
15
|
Upadhyaya G, Das A, Basu C, Agarwal T, Basak C, Chakraborty C, Halder T, Basu G, Ray S. Multiple copies of a novel amphipathic α-helix forming segment in Physcomitrella patens dehydrin play a key role in abiotic stress mitigation. J Biol Chem 2021; 296:100596. [PMID: 33781743 PMCID: PMC8100072 DOI: 10.1016/j.jbc.2021.100596] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 03/23/2021] [Accepted: 03/25/2021] [Indexed: 12/01/2022] Open
Abstract
Plants use a diverse set of proteins to mitigate various abiotic stresses. The intrinsically disordered protein dehydrin is an important member of this repertoire of proteins, characterized by a canonical amphipathic K-segment. It can also contain other stress-mitigating noncanonical segments—a likely reflection of the extremely diverse nature of abiotic stress encountered by plants. Among plants, the poikilohydric mosses have no inbuilt mechanism to prevent desiccation and therefore are likely to contain unique noncanonical stress-responsive motifs in their dehydrins. Here we report the recurring occurrence of a novel amphipathic helix-forming segment (D-segment: EGφφD(R/K)AKDAφ, where φ represents a hydrophobic residue) in Physcomitrella patens dehydrin (PpDHNA), a poikilohydric moss. NMR and CD spectroscopic experiments demonstrated the helix-forming tendency of the D-segment, with the shuffled D-segment as control. PpDHNA activity was shown to be size as well as D-segment dependent from in vitro, in vivo, and in planta studies using PpDHNA and various deletion mutants. Bimolecular fluorescence complementation studies showed that D-segment-mediated PpDHNA self-association is a requirement for stress abatement. The D-segment was also found to occur in two rehydrin proteins from Syntrichia ruralis, another poikilohydric plant like P. patens. Multiple occurrences of the D-segment in poikilohydric plant dehydrins/rehydrins, along with the experimental demonstration of the role of D-segment in stress abatement, implies that the D-segment mediates unique resurrection strategies, which may be employed by plant dehydrins that are capable of mitigating extreme stress.
Collapse
Affiliation(s)
- Gouranga Upadhyaya
- Plant Functional Genomics Laboratory, Department of Botany, University of Calcutta, Kolkata, India
| | - Arup Das
- Plant Functional Genomics Laboratory, Department of Botany, University of Calcutta, Kolkata, India
| | | | - Tanushree Agarwal
- Plant Functional Genomics Laboratory, Department of Botany, University of Calcutta, Kolkata, India
| | - Chandra Basak
- Plant Functional Genomics Laboratory, Department of Botany, University of Calcutta, Kolkata, India
| | - Chandrima Chakraborty
- Plant Functional Genomics Laboratory, Department of Botany, University of Calcutta, Kolkata, India
| | - Tanmoy Halder
- Plant Functional Genomics Laboratory, Department of Botany, University of Calcutta, Kolkata, India
| | - Gautam Basu
- Department of Biophysics, Bose Institute, Kolkata, India
| | - Sudipta Ray
- Plant Functional Genomics Laboratory, Department of Botany, University of Calcutta, Kolkata, India.
| |
Collapse
|
16
|
Halat M, Klimek-Chodacka M, Orleanska J, Baranska M, Baranski R. Electronic Circular Dichroism of the Cas9 Protein and gRNA:Cas9 Ribonucleoprotein Complex. Int J Mol Sci 2021; 22:2937. [PMID: 33805827 PMCID: PMC8002190 DOI: 10.3390/ijms22062937] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 03/09/2021] [Accepted: 03/11/2021] [Indexed: 12/26/2022] Open
Abstract
The Streptococcus pyogenes Cas9 protein (SpCas9), a component of CRISPR-based immune system in microbes, has become commonly utilized for genome editing. This nuclease forms a ribonucleoprotein (RNP) complex with guide RNA (gRNA) which induces Cas9 structural changes and triggers its cleavage activity. Here, electronic circular dichroism (ECD) spectroscopy was used to confirm the RNP formation and to determine its individual components. The ECD spectra had characteristic features differentiating Cas9 and gRNA, the former showed a negative/positive profile with maxima located at 221, 209 and 196 nm, while the latter revealed positive/negative/positive/negative pattern with bands observed at 266, 242, 222 and 209 nm, respectively. For the first time, the experimental ECD spectrum of the gRNA:Cas9 RNP complex is presented. It exhibits a bisignate positive/negative ECD couplet with maxima at 273 and 235 nm, and it differs significantly from individual spectrum of each RNP components. Additionally, the Cas9 protein and RNP complex retained biological activity after ECD measurements and they were able to bind and cleave DNA in vitro. Hence, we conclude that ECD spectroscopy can be considered as a quick and non-destructive method of monitoring conformational changes of the Cas9 protein as a result of Cas9 and gRNA interaction, and identification of the gRNA:Cas9 RNP complex.
Collapse
Affiliation(s)
- Monika Halat
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Krakow, Poland; (M.H.); (J.O.)
| | - Magdalena Klimek-Chodacka
- Department of Plant Biology and Biotechnology, Faculty of Biotechnology and Horticulture, University of Agriculture in Krakow, AL. 29 Listopada 54, 31-425 Krakow, Poland;
| | - Jagoda Orleanska
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Krakow, Poland; (M.H.); (J.O.)
| | - Malgorzata Baranska
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Krakow, Poland; (M.H.); (J.O.)
- Jagiellonian Centre for Experimental Therapeutics (JCET), Bobrzyńskiego 14, 30-348 Krakow, Poland
| | - Rafal Baranski
- Department of Plant Biology and Biotechnology, Faculty of Biotechnology and Horticulture, University of Agriculture in Krakow, AL. 29 Listopada 54, 31-425 Krakow, Poland;
| |
Collapse
|
17
|
van der Velden WJC, Smit FX, Christiansen CB, Møller TC, Hjortø GM, Larsen O, Schiellerup SP, Bräuner-Osborne H, Holst JJ, Hartmann B, Frimurer TM, Rosenkilde MM. GLP-1 Val8: A Biased GLP-1R Agonist with Altered Binding Kinetics and Impaired Release of Pancreatic Hormones in Rats. ACS Pharmacol Transl Sci 2021; 4:296-313. [PMID: 33615180 DOI: 10.1021/acsptsci.0c00193] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Indexed: 02/08/2023]
Abstract
Biased ligands that selectively confer activity in one pathway over another are pharmacologically important because biased signaling may reduce on-target side effects and improve drug efficacy. Here, we describe an N-terminal modification in the incretin hormone glucagon-like peptide (GLP-1) that alters the signaling capabilities of the GLP-1 receptor (GLP-1R) by making it G protein biased over internalization but was originally designed to confer DPP-4 resistance and thereby prolong the half-life of GLP-1. Despite similar binding affinity, cAMP production, and calcium mobilization, substitution of a single amino acid (Ala8 to Val8) in the N-terminus of GLP-1(7-36)NH2 (GLP-1 Val8) severely impaired its ability to internalize GLP-1R compared to endogenous GLP-1. In-depth binding kinetics analyses revealed shorter residence time for GLP-1 Val8 as well as a slower observed association rate. Molecular dynamics (MD) displayed weaker and less interactions of GLP-1 Val8 with GLP-1R, as well as distinct conformational changes in the receptor compared to GLP-1. In vitro validation of the MD, by receptor alanine substitutions, confirmed stronger impairments of GLP-1 Val8-mediated signaling compared to GLP-1. In a perfused rat pancreas, acute stimulation with GLP-1 Val8 resulted in a lower insulin and somatostatin secretion compared to GLP-1. Our study illustrates that profound differences in molecular pharmacological properties, which are essential for the therapeutic targeting of the GLP-1 system, can be induced by subtle changes in the N-terminus of GLP-1. This information could facilitate the development of optimized GLP-1R agonists.
Collapse
Affiliation(s)
- Wijnand J C van der Velden
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2200, Denmark
| | - Florent X Smit
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2200, Denmark
| | - Charlotte B Christiansen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2200, Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences University of Copenhagen, Copenhagen 2200, Denmark
| | - Thor C Møller
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2100, Denmark
| | - Gertrud M Hjortø
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2200, Denmark
| | - Olav Larsen
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2200, Denmark
| | - Sine P Schiellerup
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2200, Denmark
| | - Hans Bräuner-Osborne
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2100, Denmark
| | - Jens J Holst
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2200, Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences University of Copenhagen, Copenhagen 2200, Denmark
| | - Bolette Hartmann
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2200, Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences University of Copenhagen, Copenhagen 2200, Denmark
| | - Thomas M Frimurer
- Section for Metabolic Receptology, Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2200, Denmark
| | - Mette M Rosenkilde
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2200, Denmark
| |
Collapse
|
18
|
Shigedomi K, Osada S, Jelokhani-Niaraki M, Kodama H. Systematic Design and Validation of Ion Channel Stabilization of Amphipathic α-Helical Peptides Incorporating Tryptophan Residues. ACS OMEGA 2021; 6:723-732. [PMID: 33553860 PMCID: PMC7853622 DOI: 10.1021/acsomega.0c05254] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 12/17/2020] [Indexed: 05/27/2023]
Abstract
Aromatic interactions such as π-π interaction and cation-π interaction are present in membrane proteins and play important roles in both structure and function. To systematically investigate the effect of aromatic residues on the structural stability and ion permeability of peptide-formed ion channels, we designed several peptides with one or two tryptophan (Trp) residues incorporated at different positions in amphipathic α-helical peptides. Circular dichroism (CD) studies revealed the preferable position of Trp residues for self-association in these designed peptides. Systematically designed di-substituted peptides with two Trps at each helix termini demonstrated intermolecular Trp-Trp interactions caused by aggregation. In the presence of liposomes, Trp on the hydrophilic face of the peptide enhanced interaction with the lipid membrane to increase the amphipathic α-helical contents. Appropriate incorporation and positioning of Trp enabled peptides to form more stable channels and had notable effects with Trp di-substituted peptides. The ion channel forming capability of a series of these peptides showed that the cation-π interactions between Trp and Lys residues in adjacent transmembrane helices contribute to remarkable stabilization of the channel structure.
Collapse
Affiliation(s)
- Keita Shigedomi
- Department
of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan
| | - Satoshi Osada
- Department
of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan
| | - Masoud Jelokhani-Niaraki
- Department
of Chemistry and Biochemistry, Wilfrid Laurier
University, Waterloo, Ontario N2L3C5, Canada
| | - Hiroaki Kodama
- Department
of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan
| |
Collapse
|
19
|
Leusciatti M, Mannucci B, Recca T, Quadrelli P. Turn-folding in fluorescent anthracene-substituted cyclopenta[ d]isoxazoline short peptides. RSC Adv 2021; 11:19551-19559. [PMID: 35479239 PMCID: PMC9033613 DOI: 10.1039/d1ra03685h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 05/17/2021] [Indexed: 11/28/2022] Open
Abstract
Cyclopenta[d]isoxazoline aminols were used for the synthesis of β-turn mimics. The peptide chain choice ascertained the influence of their structural features on the applicability/reliability/robustness of these scaffolds as β-turn inducers and their limitations. The amino acid selection as well as steric demands can favor or disfavor the structure folding and the correct design of the peptide chains deeply influences the potential use of these nitrosocarbonyl-based compounds as turn-inducers. Cyclopenta[d]isoxazoline aminols were used for the synthesis of β-turn mimics.![]()
Collapse
Affiliation(s)
| | - Barbara Mannucci
- Centro Grandi Strumenti (CGS)
- University of Pavia
- 27100 – Pavia
- Italy
| | - Teresa Recca
- Centro Grandi Strumenti (CGS)
- University of Pavia
- 27100 – Pavia
- Italy
| | - Paolo Quadrelli
- Department of Chemistry
- University of Pavia
- 27100 – Pavia
- Italy
| |
Collapse
|
20
|
Klimpel A, Stillger K, Wiederstein JL, Krüger M, Neundorf I. Cell-permeable CaaX-peptides affect K-Ras downstream signaling and promote cell death in cancer cells. FEBS J 2020; 288:2911-2929. [PMID: 33112492 DOI: 10.1111/febs.15612] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Revised: 08/17/2020] [Accepted: 10/26/2020] [Indexed: 12/18/2022]
Abstract
Cysteine prenylation is a post-translational modification that is used by nature to control crucial biological functions of proteins, such as membrane trafficking, signal transduction, and apoptosis. It mainly occurs in eukaryotic proteins at a C-terminal CaaX box and is mediated by prenyltransferases. Since the discovery of prenylated proteins, various tools have been developed to study the mechanisms of prenyltransferases, as well as to visualize and to identify prenylated proteins. Herein, we introduce cell-permeable peptides bearing a C-terminal CaaX motif based on Ras sequences. We demonstrate that intracellular accumulation of those peptides in different cells is controlled by the presence of their CaaX motif and that they specifically interact with intracellular prenyltransferases. As proof of concept, we further highlight their utilization to alter downstream signaling of Ras proteins, particularly of K-Ras-4B, in pancreatic cancer cells. Application of this strategy holds great promise to better understand and regulate post-translational cysteine prenylation.
Collapse
Affiliation(s)
- Annika Klimpel
- Institute for Biochemistry, University of Cologne, Germany
| | | | - Janica L Wiederstein
- Institute for Genetics, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Germany
| | - Marcus Krüger
- Institute for Genetics, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Germany.,Center for Molecular Medicine (CMMC), University of Cologne, Germany
| | - Ines Neundorf
- Institute for Biochemistry, University of Cologne, Germany
| |
Collapse
|
21
|
De Zotti M, Sella L, Bolzonello A, Gabbatore L, Peggion C, Bortolotto A, Elmaghraby I, Tundo S, Favaron F. Targeted Amino Acid Substitutions in a Trichoderma Peptaibol Confer Activity against Fungal Plant Pathogens and Protect Host Tissues from Botrytis cinerea Infection. Int J Mol Sci 2020; 21:ijms21207521. [PMID: 33053906 PMCID: PMC7589190 DOI: 10.3390/ijms21207521] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 09/28/2020] [Accepted: 10/09/2020] [Indexed: 02/07/2023] Open
Abstract
Fungal species belonging to the Trichoderma genus are commonly used as biocontrol agents against several crop pathogens. Among their secondary metabolites, peptaibols are helical, antimicrobial peptides, which are structurally stable even under extreme pH and temperature conditions. The promise of peptaibols as agrochemicals is, however, hampered by poor water solubility, which inhibits efficient delivery for practical use in crop protection. Using a versatile synthetic strategy, based on green chemistry procedures, we produced water-soluble analogs of the short-length peptaibol trichogin. Although natural trichogin was inactive against the tested fungal plant pathogens (Botrytis cinerea, Bipolaris sorokiniana, Fusarium graminearum, and Penicillium expansum), three analogs completely inhibited fungal growth at low micromolar concentrations. The most effective peptides significantly reduced disease symptoms by B. cinerea on common bean and grapevine leaves and ripe grape berries without visible phytotoxic effects. An in-depth conformational analysis featuring a 3D-structure–activity relationship study indicated that the relative spatial position of cationic residues is crucial for increasing peptide fungicidal activity.
Collapse
Affiliation(s)
- Marta De Zotti
- Department of Chemistry, University of Padova, Via Marzolo 1, 35131 Padova, Italy; (L.G.); (C.P.); (A.B.)
- Correspondence:
| | - Luca Sella
- Department of Land, Environment, Agriculture and Forestry, University of Padova, Viale dell’Università 16, 35020 Legnaro (Padova), Italy; (L.S.); (A.B.); (I.E.); (S.T.); (F.F.)
| | - Angela Bolzonello
- Department of Land, Environment, Agriculture and Forestry, University of Padova, Viale dell’Università 16, 35020 Legnaro (Padova), Italy; (L.S.); (A.B.); (I.E.); (S.T.); (F.F.)
| | - Laura Gabbatore
- Department of Chemistry, University of Padova, Via Marzolo 1, 35131 Padova, Italy; (L.G.); (C.P.); (A.B.)
| | - Cristina Peggion
- Department of Chemistry, University of Padova, Via Marzolo 1, 35131 Padova, Italy; (L.G.); (C.P.); (A.B.)
| | - Alessandro Bortolotto
- Department of Chemistry, University of Padova, Via Marzolo 1, 35131 Padova, Italy; (L.G.); (C.P.); (A.B.)
- Department of Land, Environment, Agriculture and Forestry, University of Padova, Viale dell’Università 16, 35020 Legnaro (Padova), Italy; (L.S.); (A.B.); (I.E.); (S.T.); (F.F.)
| | - Ibrahim Elmaghraby
- Department of Land, Environment, Agriculture and Forestry, University of Padova, Viale dell’Università 16, 35020 Legnaro (Padova), Italy; (L.S.); (A.B.); (I.E.); (S.T.); (F.F.)
- Agricultural Research Center, Central Laboratory of Organic Agriculture 9, Cairo Univ. St., Giza 12619, Egypt
| | - Silvio Tundo
- Department of Land, Environment, Agriculture and Forestry, University of Padova, Viale dell’Università 16, 35020 Legnaro (Padova), Italy; (L.S.); (A.B.); (I.E.); (S.T.); (F.F.)
| | - Francesco Favaron
- Department of Land, Environment, Agriculture and Forestry, University of Padova, Viale dell’Università 16, 35020 Legnaro (Padova), Italy; (L.S.); (A.B.); (I.E.); (S.T.); (F.F.)
| |
Collapse
|
22
|
Conceição K, de Cena GL, da Silva VA, de Oliveira Neto XA, de Andrade VM, Tada DB, Richardson M, de Andrade SA, Dias SA, Castanho MARB, Lopes-Ferreira M. Design of bioactive peptides derived from CART sequence isolated from the toadfish Thalassophryne nattereri. 3 Biotech 2020; 10:162. [PMID: 32206496 PMCID: PMC7060301 DOI: 10.1007/s13205-020-2151-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2019] [Accepted: 02/18/2020] [Indexed: 10/24/2022] Open
Abstract
The emergence of bacterial resistance due to the indiscriminate use of antibiotics warrants the need for developing new bioactive agents. In this context, antimicrobial peptides are highly useful for managing resistant microbial strains. In this study, we report the isolation and characterization of peptides obtained from the venom of the toadfish Thalassophryne nattereri. These peptides were active against Gram-positive and Gram-negative bacteria and fungi. The primary amino acid sequences showed similarity to Cocaine and Amphetamine Regulated Transcript peptides, and two peptide analogs-Tn CRT2 and Tn CRT3-were designed using the AMPA algorithm based on these sequences. The analogs were subjected to physicochemical analysis and antimicrobial screening and were biologically active at concentrations ranging from 2.1 to 13 µM. Zeta potential analysis showed that the peptide analogs increased the positive charge on the cell surface of Gram-positive and Gram-negative bacteria. The toxicity of Tn CRT2 and Tn CRT3 were analyzed in vitro using a hemolytic assay and tetrazolium salt reduction in fibroblasts and was found to be significant only at high concentrations (up to 40 µM). These results suggest that this methodological approach is appropriate to design novel antimicrobial peptides to fight bacterial infections and represents a new and promising discovery in fish venom.
Collapse
Affiliation(s)
- Katia Conceição
- Laboratório de Bioquímica de Peptídeos, Universidade Federal de São Paulo-UNIFESP, Rua Talim, 330, São José dos Campos, Brazil
| | - Gabrielle L. de Cena
- Laboratório de Bioquímica de Peptídeos, Universidade Federal de São Paulo-UNIFESP, Rua Talim, 330, São José dos Campos, Brazil
| | - Verônica A. da Silva
- Laboratório de Bioquímica de Peptídeos, Universidade Federal de São Paulo-UNIFESP, Rua Talim, 330, São José dos Campos, Brazil
| | - Xisto Antonio de Oliveira Neto
- Laboratório de Bioquímica de Peptídeos, Universidade Federal de São Paulo-UNIFESP, Rua Talim, 330, São José dos Campos, Brazil
| | - Vitor Martins de Andrade
- Laboratório de Bioquímica de Peptídeos, Universidade Federal de São Paulo-UNIFESP, Rua Talim, 330, São José dos Campos, Brazil
| | - Dayane Batista Tada
- Laboratório de Nanomateriais e Nanotoxicologia, Universidade Federal de São Paulo-UNIFESP, Rua Talim, 330, São José dos Campos, Brazil
| | - Michael Richardson
- Centro de Pesquisa e Desenvolvimento Prof. Carlos R. Diniz, Fundação Ezequiel Dias, Rua Conde Pereira Carneiro 80, Belo Horizonte, MG Brazil
| | - Sonia A. de Andrade
- Laboratório Especial de Toxicologia Aplicada, Instituto Butantan, Av. Vital Brasil, São Paulo, 1500 Brazil
| | - Susana A. Dias
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649‐028 Lisboa, Portugal
| | - Miguel A. R. B. Castanho
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649‐028 Lisboa, Portugal
| | - Mônica Lopes-Ferreira
- Laboratório Especial de Toxicologia Aplicada, Instituto Butantan, Av. Vital Brasil, São Paulo, 1500 Brazil
| |
Collapse
|
23
|
Saraswat J, Wani FA, Dar KI, Rizvi MMA, Patel R. Noncovalent Conjugates of Ionic Liquid with Antibacterial Peptide Melittin: An Efficient Combination against Bacterial Cells. ACS OMEGA 2020; 5:6376-6388. [PMID: 32258872 PMCID: PMC7114158 DOI: 10.1021/acsomega.9b03777] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 02/24/2020] [Indexed: 06/11/2023]
Abstract
Growing antibiotic resistance has become a major health problem and has encouraged many researchers to find an alternative class of antibiotics. Combination therapy (covalent/noncovalent) is supposed to increase antibacterial activity leading to a decrease in administration dosage, thus lowering the risk of adverse side effects. The covalent coupling sometimes leads to instability and loss in the structure of AMPs. Therefore, herein, we have reported innovative research involving the noncovalent coupling of melittin (MEL), an antimicrobial peptide with a series of synthesized less toxic pyrrolidinium-based ionic liquids (ILs) for which MTT assay was performed. The antibacterial results of conjugates showed remarkable improvement in the MIC value as compared to MEL and ILs alone against Escherichia coli and Staphylococcus aureus . In addition, hemocompatibility results suggested good selectivity of the noncovalent conjugate as a potential antibiotic agent. Further, the docking study was employed to acquire the most favorable conformation of MEL in the presence of ILs. The best possible complex was further studied using various spectroscopic techniques, which showed appreciable binding and stability of the complex.
Collapse
Affiliation(s)
- Juhi Saraswat
- Biophysical
Chemistry Laboratory, Centre for Interdisciplinary Research in Basic
Sciences, Jamia Millia Islamia, New Delhi 110025, India
| | - Farooq Ahmed Wani
- Biophysical
Chemistry Laboratory, Centre for Interdisciplinary Research in Basic
Sciences, Jamia Millia Islamia, New Delhi 110025, India
| | | | | | - Rajan Patel
- Biophysical
Chemistry Laboratory, Centre for Interdisciplinary Research in Basic
Sciences, Jamia Millia Islamia, New Delhi 110025, India
| |
Collapse
|
24
|
Borocci S, Della Pelle G, Ceccacci F, Olivieri C, Buonocore F, Porcelli F. Structural Analysis and Design of Chionodracine-Derived Peptides Using Circular Dichroism and Molecular Dynamics Simulations. Int J Mol Sci 2020; 21:E1401. [PMID: 32092980 PMCID: PMC7073106 DOI: 10.3390/ijms21041401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 02/12/2020] [Accepted: 02/17/2020] [Indexed: 12/18/2022] Open
Abstract
Antimicrobial peptides have been identified as one of the alternatives to the extensive use of common antibiotics as they show a broad spectrum of activity against human pathogens. Among these is Chionodracine (Cnd), a host-defense peptide isolated from the Antarctic icefish Chionodraco hamatus, which belongs to the family of Piscidins. Previously, we demonstrated that Cnd and its analogs display high antimicrobial activity against ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter species). Herein, we investigate the interactions with lipid membranes of Cnd and two analogs, Cnd-m3 and Cnd-m3a, showing enhanced potency. Using a combination of Circular Dichroism, fluorescence spectroscopy, and all-atom Molecular Dynamics (MD) simulations, we determined the structural basis for the different activity among these peptides. We show that all peptides are predominantly unstructured in water and fold, preferentially as α-helices, in the presence of lipid vesicles of various compositions. Through a series of MD simulations of 400 ns time scale, we show the effect of mutations on the structure and lipid interactions of Cnd and its analogs. By explaining the structural basis for the activity of these analogs, our findings provide structural templates to design minimalistic peptides for therapeutics.
Collapse
Affiliation(s)
- Stefano Borocci
- Department for Innovation in Biological, Agrofood and Forest Systems, University of Tuscia, 01100 Viterbo, Italy; (S.B.); (G.D.P.); (F.B.)
- CNR—Institute for Biological Systems, Via Salaria, Km 29.500, 00015 Monterotondo, 00015 Rome, Italy
| | - Giulia Della Pelle
- Department for Innovation in Biological, Agrofood and Forest Systems, University of Tuscia, 01100 Viterbo, Italy; (S.B.); (G.D.P.); (F.B.)
| | - Francesca Ceccacci
- CNR—Institute for Biological Systems, Sede Secondaria di Roma-Meccanismi di Reazione, 00185 Rome, Italy;
| | - Cristina Olivieri
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA;
| | - Francesco Buonocore
- Department for Innovation in Biological, Agrofood and Forest Systems, University of Tuscia, 01100 Viterbo, Italy; (S.B.); (G.D.P.); (F.B.)
| | - Fernando Porcelli
- Department for Innovation in Biological, Agrofood and Forest Systems, University of Tuscia, 01100 Viterbo, Italy; (S.B.); (G.D.P.); (F.B.)
| |
Collapse
|
25
|
Di Silvio S, Bologna F, Milli L, Giuri D, Zanna N, Castellucci N, Monari M, Calvaresi M, Górecki M, Angelici G, Tomasini C, Pescitelli G. Elusive π-helical peptide foldamers spotted by chiroptical studies. Org Biomol Chem 2020; 18:865-877. [PMID: 31845697 DOI: 10.1039/c9ob02313e] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
A series of oligomers containing alternate l-Ala and pGlu (pyroglutamic acid) both in the L and D form have been prepared and conformationally investigated by X-ray, NMR, UV/ECD, IR/VCD and molecular modelling. X-ray diffraction analysis was possible for the shortest oligomers LL-1 and LD-1. Molecular dynamics simulations of the oligomers demonstrated that the energy landscapes of the LL-series are broad. In contrast, the energy landscapes of the LD-series are characterized by well-defined minima corresponding to specific conformational structures. A single well-defined minimum exists in the energy landscape of the largest oligomer LD-8, corresponding to a precise conformation, characterized by i + 5 →i N-HO[double bond, length as m-dash]C hydrogen bonds, typical of a π-helix. ECD and VCD spectra were measured to identify the chiroptical profiles of the oligomers. The most striking element in the ECD spectra of the LD-series is their exceptionally strong intensity, which confirms that these polypeptides attain a high degree of helical order. VCD spectra for the LD-series are well reproduced by frequency calculations when π-helix folds are employed as input structures, suggesting that a symmetrical VCD couplet around 1720 cm-1 can be taken as the VCD signature of π-helices.
Collapse
Affiliation(s)
- Sergio Di Silvio
- Dipartimento di Chimica "Giacomo Ciamician", Alma Mater Studiorum Università di Bologna, Via F. Selmi 2, 40126 Bologna, Italy.
| | - Fabio Bologna
- Dipartimento di Chimica "Giacomo Ciamician", Alma Mater Studiorum Università di Bologna, Via F. Selmi 2, 40126 Bologna, Italy.
| | - Lorenzo Milli
- Dipartimento di Chimica "Giacomo Ciamician", Alma Mater Studiorum Università di Bologna, Via F. Selmi 2, 40126 Bologna, Italy.
| | - Demetra Giuri
- Dipartimento di Chimica "Giacomo Ciamician", Alma Mater Studiorum Università di Bologna, Via F. Selmi 2, 40126 Bologna, Italy.
| | - Nicola Zanna
- Dipartimento di Chimica "Giacomo Ciamician", Alma Mater Studiorum Università di Bologna, Via F. Selmi 2, 40126 Bologna, Italy.
| | - Nicola Castellucci
- Dipartimento di Chimica "Giacomo Ciamician", Alma Mater Studiorum Università di Bologna, Via F. Selmi 2, 40126 Bologna, Italy.
| | - Magda Monari
- Dipartimento di Chimica "Giacomo Ciamician", Alma Mater Studiorum Università di Bologna, Via F. Selmi 2, 40126 Bologna, Italy.
| | - Matteo Calvaresi
- Dipartimento di Chimica "Giacomo Ciamician", Alma Mater Studiorum Università di Bologna, Via F. Selmi 2, 40126 Bologna, Italy.
| | - Marcin Górecki
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Moruzzi 13, 56124 Pisa, Italy. and Institute of Organic Chemistry, Polish Academy of Sciences, Warsaw 01-224, Poland
| | - Gaetano Angelici
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Moruzzi 13, 56124 Pisa, Italy.
| | - Claudia Tomasini
- Dipartimento di Chimica "Giacomo Ciamician", Alma Mater Studiorum Università di Bologna, Via F. Selmi 2, 40126 Bologna, Italy.
| | - Gennaro Pescitelli
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Moruzzi 13, 56124 Pisa, Italy.
| |
Collapse
|
26
|
Ponomarenko NS, Kokhan O, Pokkuluri PR, Mulfort KL, Tiede DM. Examination of abiotic cofactor assembly in photosynthetic biomimetics: site-specific stereoselectivity in the conjugation of a ruthenium(II) tris(bipyridine) photosensitizer to a multi-heme protein. PHOTOSYNTHESIS RESEARCH 2020; 143:99-113. [PMID: 31925630 PMCID: PMC6989566 DOI: 10.1007/s11120-019-00697-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 12/02/2019] [Indexed: 05/18/2023]
Abstract
To understand design principles for assembling photosynthetic biohybrids that incorporate precisely-controlled sites for electron injection into redox enzyme cofactor arrays, we investigated the influence of chirality in assembly of the photosensitizer ruthenium(II)bis(2,2'-bipyridine)(4-bromomethyl-4'-methyl-2,2'-bipyridine), Ru(bpy)2(Br-bpy), when covalently conjugated to cysteine residues introduced by site-directed mutagenesis in the triheme periplasmic cytochrome A (PpcA) as a model biohybrid system. For two investigated conjugates that show ultrafast electron transfer, A23C-Ru and K29C-Ru, analysis by circular dichroism spectroscopy, CD, demonstrated site-specific chiral discrimination as a factor emerging from the close association between [Ru(bpy)3]2+ and heme cofactors. CD analysis showed the A23C-Ru and K29C-Ru conjugates to have distinct, but opposite, stereoselectivity for the Λ and Δ-Ru(bpy)2(Br-bpy) enantiomers, with enantiomeric excesses of 33.1% and 65.6%, respectively. In contrast, Ru(bpy)2(Br-bpy) conjugation to a protein site with high flexibility, represented by the E39C-Ru construct, exhibited a nearly negligible chiral selectivity, measured by an enantiomeric excess of 4.2% for the Λ enantiomer. Molecular dynamics simulations showed that site-specific stereoselectivity reflects steric constraints at the conjugating sites and that a high degree of chiral selectivity correlates to reduced structural disorder for [Ru(bpy)3]2+ in the linked assembly. This work identifies chiral discrimination as means to achieve site-specific, precise geometric positioning of introduced photosensitizers relative to the heme cofactors in manner that mimics the tuning of cofactors in photosynthesis.
Collapse
Affiliation(s)
- Nina S Ponomarenko
- Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL, 60439, USA.
| | - Oleksandr Kokhan
- Department of Chemistry and Biochemistry, James Madison University, 901 Carrier Drive, Harrisonburg, VA, 22807, USA
| | - Phani R Pokkuluri
- Biosciences Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL, 60439, USA
| | - Karen L Mulfort
- Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL, 60439, USA
| | - David M Tiede
- Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL, 60439, USA.
| |
Collapse
|
27
|
Structural and Biophysical Analyses of Human N-Myc Downstream-Regulated Gene 3 (NDRG3) Protein. Biomolecules 2020; 10:biom10010090. [PMID: 31935861 PMCID: PMC7022630 DOI: 10.3390/biom10010090] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 12/31/2019] [Accepted: 01/01/2020] [Indexed: 01/07/2023] Open
Abstract
The N-Myc downstream-regulated gene (NDRG) family belongs to the α/β-hydrolase fold and is known to exert various physiologic functions in cell proliferation, differentiation, and hypoxia-induced cancer metabolism. In particular, NDRG3 is closely related to proliferation and migration of prostate cancer cells, and recent studies reported its implication in lactate-triggered hypoxia responses or tumorigenesis. However, the underlying mechanism for the functions of NDRG3 remains unclear. Here, we report the crystal structure of human NDRG3 at 2.2 Å resolution, with six molecules in an asymmetric unit. While NDRG3 adopts the α/β-hydrolase fold, complete substitution of the canonical catalytic triad residues to non-reactive residues and steric hindrance around the pseudo-active site seem to disable the α/β-hydrolase activity. While NDRG3 shares a high similarity to NDRG2 in terms of amino acid sequence and structure, NDRG3 exhibited remarkable structural differences in a flexible loop corresponding to helix α6 of NDRG2 that is responsible for tumor suppression. Thus, this flexible loop region seems to play a distinct role in oncogenic progression induced by NDRG3. Collectively, our studies could provide structural and biophysical insights into the molecular characteristics of NDRG3.
Collapse
|
28
|
Phosphorylation of TIP3 Aquaporins during Phaseolus vulgaris Embryo Development. Cells 2019; 8:cells8111362. [PMID: 31683651 PMCID: PMC6912600 DOI: 10.3390/cells8111362] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 10/22/2019] [Accepted: 10/23/2019] [Indexed: 11/19/2022] Open
Abstract
The membrane phosphoproteome in plant seed changes dynamically during embryo development. We examined the patterns of Phaseolus vulgaris (common bean) seed membrane protein phosphorylation from the mid-maturation stage until two days after germination. Serine and threonine phosphorylation declined during seed maturation while tyrosine phosphorylation remained relatively constant. We discovered that the aquaporin PvTIP3;1 is the primary seed membrane phosphoprotein, and PvTIP3;2 shows a very low level of expression. The level of phosphorylated Ser7 in PvTIP3;1 increased four-fold after seed maturation. Since phosphorylation increases water channel activity, we infer that water transport by PvTIP3;1 is highest in dry and germinating seeds, which would be optimal for seed imbibition. By the use of isoform-specific, polyclonal peptide antibodies, we found that PvTIP3;2 is expressed in a developmental pattern similar to PvTIP3;1. Unexpectedly, PvTIP3;2 is tyrosine phosphorylated following seed maturation, which may suggest a mechanism for the regulation of PvTIP3;2 following seed germination. Analysis of protein secondary structure by circular dichroism spectroscopy indicated that the amino-terminal domain of PvTIP3;1 is generally unstructured, and phosphorylation increases polyproline II (PPII) helical structure. The carboxy-terminal domain also gains PPII character, but in a pH-dependent manner. These structural changes are a first step to understand TIP3 aquaporin regulation.
Collapse
|
29
|
Narayan A, Bhattacharjee K, Naganathan AN. Thermally versus Chemically Denatured Protein States. Biochemistry 2019; 58:2519-2523. [PMID: 31083972 DOI: 10.1021/acs.biochem.9b00089] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Protein unfolding thermodynamic parameters are conventionally extracted from equilibrium thermal and chemical denaturation experiments. Despite decades of work, the degree of structure and the compactness of denatured states populated in these experiments are still open questions. Here, building on previous works, we show that thermally and chemically denatured protein states are distinct from the viewpoint of far-ultraviolet circular dichroism experiments that report on the local conformational status of peptide bonds. The differences identified are independent of protein length, structural class, or experimental conditions, highlighting the presence of two sub-ensembles within the denatured states. The sub-ensembles, UT and UD for thermally induced and denaturant-induced unfolded states, respectively, can exclusively exchange populations as a function of temperature at high chemical denaturant concentrations. Empirical analysis suggests that chemically denatured states are ∼50% more expanded than the thermally denatured chains of the same protein. Our observations hint that the strength of protein backbone-backbone interactions and identity versus backbone-solvent/co-solvent interactions determine the conformational distributions. We discuss the implications for protein folding mechanisms, the heterogeneity in relaxation rates, and folding diffusion coefficients.
Collapse
Affiliation(s)
- Abhishek Narayan
- Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences , Indian Institute of Technology Madras , Chennai 600036 , India
| | - Kabita Bhattacharjee
- Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences , Indian Institute of Technology Madras , Chennai 600036 , India
| | - Athi N Naganathan
- Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences , Indian Institute of Technology Madras , Chennai 600036 , India
| |
Collapse
|
30
|
Affiliation(s)
- Xiao Hu
- School of Pharmacy, Jiangsu University, 301 Xuefu Road Zhenjiang Jiangsu 212013 China
| | - Bo Wu
- School of Pharmacy, Jiangsu University, 301 Xuefu Road Zhenjiang Jiangsu 212013 China
| | - Weiping Zheng
- School of Pharmacy, Jiangsu University, 301 Xuefu Road Zhenjiang Jiangsu 212013 China
| |
Collapse
|
31
|
Optogenetic Navigation of Routes Leading to Protein Amyloidogenesis in Bacteria. J Mol Biol 2019; 431:1186-1202. [PMID: 30721672 DOI: 10.1016/j.jmb.2019.01.037] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 01/24/2019] [Accepted: 01/28/2019] [Indexed: 01/10/2023]
Abstract
Modulation of liquid-liquid and liquid-hydrogel phase transitions is central to avoid the cytotoxic aggregation of proteins in eukaryotic cells, but knowledge on its relevance in bacteria is limited. Here the power of optogenetics to engineer proteins as light-responsive switches has been used to control the balance between solubility and aggregation for LOV2-WH1, a chimera between the plant blue light-responsive domain LOV2 and the bacterial prion-like protein RepA-WH1. These proteins were first linked by fusing, as a continuous α-helix, the C-terminal photo-transducer Jα helix in LOV2 with the N-terminal domain-closure α1 helix in RepA-WH1, and then improved for light-responsiveness by including mutations in the Jα moiety. In the darkness and in a crowded solution in vitro, LOV2-WH1 nucleates the irreversible assembly of amyloid fibers into a hydrogel. However, under blue light illumination, LOV2-WH1 assembles as soluble oligomers. When expressed in Escherichia coli, LOV2-WH1 forms in the darkness large intracellular amyloid inclusions compatible with bacterial proliferation. Strikingly, under blue light, LOV2-WH1 aggregates decrease in size, while they become detrimental for bacterial growth. LOV2-WH1 optogenetics governs the assembly of mutually exclusive inert amyloid fibers or cytotoxic oligomers, thus enabling the navigation of the conformational landscape of protein amyloidogenesis to generate potential photo-activated anti-bacterial devices (optobiotics).
Collapse
|
32
|
Sahu S, Sheet T, Banerjee R. Interaction landscape of a 'C αNN' motif with arsenate and arsenite: a potential peptide-based scavenger of arsenic. RSC Adv 2019; 9:1062-1074. [PMID: 35517606 PMCID: PMC9059529 DOI: 10.1039/c8ra08225a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 12/08/2018] [Indexed: 12/01/2022] Open
Abstract
Arsenic (As) is a toxic metalloid that has drawn immense attention from the scientific community recently due to its fatal effects through its unwanted occurrence in ground water around the globe. The presence of an excess amount of water soluble arsenate and/or arsenite salt (permissible limit 10 μg L-1 as recommended by the WHO) in water has been correlated with several human diseases. Although arsenate (HAsO4 2-) is a molecular analogue of phosphate (HPO4 2-), phosphate is indispensable for life, while arsenic and its salts are toxic. Therefore, it is worthwhile to focus on the removal of arsenic from water. Towards this end, the design of peptide-based scaffolds for the recognition of arsenate and arsenite would add a new dimension. Utilizing the stereochemical similarity between arsenate (HAsO4 2-) and phosphate (HPO4 2-), we successfully investigated the recognition of arsenate and arsenite with a naturally occurring novel phosphate binding 'CαNN' motif and its related designed analogues. Using computational as well as biophysical approaches, for the first time, we report here that a designed peptide-based scaffold based on the 'CαNN' motif can recognize anions of arsenic in a thermodynamically favorable manner in a context-free system. This peptide-based arsenic binding agent has the potential for future development as a scavenger of arsenic anions to obtain arsenic free water.
Collapse
Affiliation(s)
- Subhankar Sahu
- Department of Biotechnology and Head Department of Bioinformatics, Maulana Abul Kalam Azad University of Technology, West Bengal (Formerly Known as West Bengal University of Technology) BF-142, Salt Lake Kolkata 700064 West Bengal India
| | - Tridip Sheet
- Department of Biotechnology and Head Department of Bioinformatics, Maulana Abul Kalam Azad University of Technology, West Bengal (Formerly Known as West Bengal University of Technology) BF-142, Salt Lake Kolkata 700064 West Bengal India
| | - Raja Banerjee
- Department of Biotechnology and Head Department of Bioinformatics, Maulana Abul Kalam Azad University of Technology, West Bengal (Formerly Known as West Bengal University of Technology) BF-142, Salt Lake Kolkata 700064 West Bengal India
| |
Collapse
|
33
|
Klimpel A, Neundorf I. Bifunctional peptide hybrids targeting the matrix of mitochondria. J Control Release 2018; 291:147-156. [DOI: 10.1016/j.jconrel.2018.10.029] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 10/05/2018] [Accepted: 10/22/2018] [Indexed: 12/17/2022]
|
34
|
Berbeć S, Dec R, Molodenskiy D, Wielgus-Kutrowska B, Johannessen C, Hernik-Magoń A, Tobias F, Bzowska A, Ścibisz G, Keiderling TA, Svergun D, Dzwolak W. β2-Type Amyloidlike Fibrils of Poly-l-glutamic Acid Convert into Long, Highly Ordered Helices upon Dissolution in Dimethyl Sulfoxide. J Phys Chem B 2018; 122:11895-11905. [DOI: 10.1021/acs.jpcb.8b08308] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Sylwia Berbeć
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, 1 Pasteur Street, 02-093 Warsaw, Poland
| | - Robert Dec
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, 1 Pasteur Street, 02-093 Warsaw, Poland
| | - Dmitry Molodenskiy
- European Molecular Biology Laboratory, Hamburg Outstation, c/o DESY, Hamburg 22607, Germany
| | - Beata Wielgus-Kutrowska
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw 02-093, Poland
| | | | - Agnieszka Hernik-Magoń
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, 1 Pasteur Street, 02-093 Warsaw, Poland
| | - Fernando Tobias
- Department of Chemistry, University of Illinois at Chicago, Chicago 60607-7061, United States
| | - Agnieszka Bzowska
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw 02-093, Poland
| | - Grzegorz Ścibisz
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, 1 Pasteur Street, 02-093 Warsaw, Poland
| | - Timothy A. Keiderling
- Department of Chemistry, University of Illinois at Chicago, Chicago 60607-7061, United States
| | - Dmitri Svergun
- European Molecular Biology Laboratory, Hamburg Outstation, c/o DESY, Hamburg 22607, Germany
| | - Wojciech Dzwolak
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, 1 Pasteur Street, 02-093 Warsaw, Poland
| |
Collapse
|
35
|
Design of a novel cell-permeable chimeric peptide to promote wound healing. Sci Rep 2018; 8:16279. [PMID: 30389988 PMCID: PMC6214915 DOI: 10.1038/s41598-018-34684-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 10/22/2018] [Indexed: 01/06/2023] Open
Abstract
Biological membranes are impermeable to almost all compounds having a molecular weight greater than 500 Da. Recently, cell penetrating peptides (CPPs) as delivery vehicles have attracted great interest in the medical sector for the development of novel therapeutic agents or cosmetic products. Herein, a wound healing promoting sequence, namely Tylotoin, was covalently coupled with a cell penetrating peptide to improve the delivery of Tylotoin across cellular membranes. Indeed, internalization studies indicated that the cellular uptake of these novel peptide conjugates into keratinocytes was significantly improved accompanied by good tolerability. In a scratch wound closure assay used to investigate the wound healing capability, the most promising novel peptide chimera (Tylotoin-sC18*) was found to promote the migration of keratinocytes indicating that the fusion to Tylotoin did not cause any loss in its activity. Even more, proliferative effects on keratinocytes were observed, an important step during the wound healing process. Still more encouraging is the capability of Tylotoin-sC18* to exhibit strong antimicrobial activities since the process of wound healing is often affected by bacterial infections. Owing to their multiple functions, the novel peptide chimera may have potential as future agents for the treatment of infected wounds.
Collapse
|
36
|
Memeo M, Bruschi M, Bergonzi L, Desimoni G, Faita G, Quadrelli P. Cyclopenta[ d]isoxazoline β-Turn Mimics: Synthetic Approach, Turn Driving Force, Scope, and Limitations. ACS OMEGA 2018; 3:13551-13558. [PMID: 31458062 PMCID: PMC6645019 DOI: 10.1021/acsomega.8b01670] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 09/25/2018] [Indexed: 06/10/2023]
Abstract
Model β-turn inducers were prepared from constrained oxazanorbornene aminols. Taking advantage of the starting materials geometry, new diastereoisomeric compounds were synthesized, introducing different amino acidic residues. The products were spectroscopically characterized (VT and NMR titration). Temperature coefficients in dimethyl sulfoxide denote the existence of an intramolecular hydrogen bond. Chiroptical properties disclosed a β-turn arrangement of the synthesized compounds. The fused isoxazoline ring constraints the cyclopentane moiety, stabilizing a boatlike conformation that ensures the turn efficiency but limiting the accessibility to hindered amino acids.
Collapse
|
37
|
Acremotins A-D, peptaibiotics produced by the soil-derived fungus Acremonium persicinum SC0105. J Antibiot (Tokyo) 2018; 71:927-938. [PMID: 30089870 DOI: 10.1038/s41429-018-0086-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 07/10/2018] [Accepted: 07/23/2018] [Indexed: 11/08/2022]
Abstract
Four new peptaibiotics, acremotins A-D (1-4) featuring three α,α-dialkylated amino acid-imino acid motifs and an unreduced C-terminal residue, along with the known peptaibiotic XR586 (5) were isolated from the solid cultures of the soil-derived fungus Acremonium persicinum SC0105. Their primary structures were characterized by detailed analysis of the HRESIMS/MS fragmentation pattern combined with comprehensive interpretation of the 1D and 2D NMR spectroscopic data. The absolute configurations of amino acid residues were determined by the advanced Marfey's method. Sequence alignment result shows that 1-4 are closely related to zervamicin IIB and emerimicin IIA, thus belong to peptaibiotic subfamily-3 (SF3). The three-dimensional (3D) structure of 4 was established by theoretical conformational analysis using the ab initio density functional theory (DFT) method, which, together with the CD spectrum, indicated an amphiphilic and helical structure for 4. 1-5 actively inhibited the growth of gram-positive bacterial pathogens, and amongst them 4 was the most potent compound showing MIC of 12.5 and 6.25 µg/ml against S. aureu and MRSA strains, respectively. 1-5 were also cytotoxic against three human cancer cell lines with IC50 ranging from 1.2 to 21.6 μM.
Collapse
|
38
|
Gronewold A, Horn M, Neundorf I. Design and biological characterization of novel cell-penetrating peptides preferentially targeting cell nuclei and subnuclear regions. Beilstein J Org Chem 2018; 14:1378-1388. [PMID: 29977402 PMCID: PMC6009097 DOI: 10.3762/bjoc.14.116] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 05/16/2018] [Indexed: 12/16/2022] Open
Abstract
Within this study, we report about the design and biological characterization of novel cell-penetrating peptides (CPPs) with selective suborganelle-targeting properties. The nuclear localization sequence N50, as well as the nucleoli-targeting sequence NrTP, respectively, were fused to a shortened version of the cell-penetrating peptide sC18. We examined cellular uptake, subcellular fate and cytotoxicity of these novel peptides, N50-sC18* and NrTP-sC18*, and found that they are nontoxic up to a concentration of 50 or 100 µM depending on the cell lines used. Moreover, detailed cellular uptake studies revealed that both peptides enter cells via energy-independent uptake, although endocytotic processes cannot completely excluded. However, initial drug delivery studies demonstrated the high versatility of these new peptides as efficient transport vectors targeting specifically nuclei and nucleoli. In future, they could be further explored as parts of newly created peptide-drug conjugates.
Collapse
Affiliation(s)
- Anja Gronewold
- Department of Chemistry, Biochemistry, University of Cologne, Zuelpicher Str. 47a, 50674 Cologne, Germany
| | - Mareike Horn
- Department of Chemistry, Biochemistry, University of Cologne, Zuelpicher Str. 47a, 50674 Cologne, Germany
| | - Ines Neundorf
- Department of Chemistry, Biochemistry, University of Cologne, Zuelpicher Str. 47a, 50674 Cologne, Germany
| |
Collapse
|
39
|
Pal S, Prabhakaran EN. Hydrogen bond surrogate stabilized water soluble 310-helix from a disordered pentapeptide containing coded α-amino acids. Tetrahedron Lett 2018. [DOI: 10.1016/j.tetlet.2018.05.029] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
|
40
|
Salas RL, Garcia JKDL, Miranda ACR, Rivera WL, Nellas RB, Sabido PMG. Effects of truncation of the peptide chain on the secondary structure and bioactivities of palmitoylated anoplin. Peptides 2018; 104:7-14. [PMID: 29614317 DOI: 10.1016/j.peptides.2018.03.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 03/28/2018] [Accepted: 03/30/2018] [Indexed: 12/29/2022]
Abstract
Anoplin (GLLKRIKTLL-NH2) is of current interest due to its short sequence and specificity towards bacteria. Recent studies on anoplin have shown that truncation and acylation compromises its antimicrobial activity and specificity, respectively. In this study, truncated analogues (pal-ano-9 to pal-ano-5) of palmitoylated anoplin (pal-anoplin) were synthesized to determine the effects of C-truncation on its bioactivities. Moreover, secondary structure of each analogue using circular dichroism (CD) spectroscopy was determined to correlate with bioactivities. Interestingly, pal-anoplin, pal-ano-9 and pal-ano-6 were helical in water, unlike anoplin. In contrast, pal-ano-8, pal-ano-7 and pal-ano-5, with polar amino acid residues at the C-terminus, were random coil in water. Nevertheless, all the peptides folded into helical structures in 30% trifluoroethanol/water (TFE/H2O) except for the shortest analogue pal-ano-5. Hydrophobicity played a significant role in the enhancement of activity against bacteria E. coli and S. aureus as all lipopeptides including the random coil pal-ano-5 were more active than the parent anoplin. Meanwhile, the greatest improvement in activity against the fungus C. albicans was observed for pal-anoplin analogues (pal-ano-9 and pal-ano-6) that were helical in water. Although, hydrophobicity is a major factor in the secondary structure and antimicrobial activity, it appears that the nature of amino acids at the C-terminus also influence folding of lipopeptides in water and its antifungal activity. Moreover, the hemolytic activity of the analogues was found to correlate with hydrophobicity, except for the least hemolytic, pal-ano-5. Since most of the analogues are more potent and shorter than anoplin, they are promising drug candidates for further development.
Collapse
Affiliation(s)
- Remmer L Salas
- Institute of Chemistry, College of Science, University of the Philippines, Diliman, Quezon City, 1101, Philippines
| | - Jan Kathryne D L Garcia
- Institute of Chemistry, College of Science, University of the Philippines, Diliman, Quezon City, 1101, Philippines; Natural Sciences Research Institute, University of the Philippines, Diliman, Quezon City, 1101, Philippines
| | - Ana Carmela R Miranda
- Institute of Chemistry, College of Science, University of the Philippines, Diliman, Quezon City, 1101, Philippines
| | - Windell L Rivera
- Natural Sciences Research Institute, University of the Philippines, Diliman, Quezon City, 1101, Philippines; Institute of Biology, College of Science, University of the Philippines, Diliman, Quezon City, 1101, Philippines
| | - Ricky B Nellas
- Institute of Chemistry, College of Science, University of the Philippines, Diliman, Quezon City, 1101, Philippines; Natural Sciences Research Institute, University of the Philippines, Diliman, Quezon City, 1101, Philippines
| | - Portia Mahal G Sabido
- Institute of Chemistry, College of Science, University of the Philippines, Diliman, Quezon City, 1101, Philippines; Natural Sciences Research Institute, University of the Philippines, Diliman, Quezon City, 1101, Philippines.
| |
Collapse
|
41
|
Hamley IW, Castelletto V, Dehsorkhi A, Torras J, Aleman C, Portnaya I, Danino D. The Conformation and Aggregation of Proline-Rich Surfactant-Like Peptides. J Phys Chem B 2018; 122:1826-1835. [PMID: 29357666 DOI: 10.1021/acs.jpcb.7b11463] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The secondary structure of proline-rich surfactant-like peptides is examined for the first time and is found to be influenced by charged end groups in peptides P6K, P6E, and KP6E and an equimolar mixture of P6K and P6E. The peptides exhibit a conformational transition from unordered to polyproline II (PPII) above a critical concentration, detected from circular dichroism (CD) measurements and unexpectedly from fluorescence dye probe measurements. Isothermal titration calorimetry (ITC) measurements provided the Gibbs energies of hydration of P6K and P6E, which correspond essentially to the hydration energies of the terminal charged residues. A detailed analysis of peptide conformation for these peptides was performed using density functional theory calculations, and this was used as a basis for hybrid quantum mechanics/molecular mechanics molecular dynamics (QM/MM MD) simulations. Quantum mechanics simulations in implicit water show both peptides (and their 1:1 mixture) exhibit PPII conformations. However, hybrid QM/MM MD simulations suggest that some deviations from this conformation are present for P6K and P6E in peptide bonds close to the charged residue, whereas in the 1:1 mixture a PPII structure is observed. Finally, aggregation of the peptides was investigated using replica exchange molecular dynamics simulations. These reveal a tendency for the average aggregate size (as measured by the radius of gyration) to increase with increasing temperature, which is especially marked for P6K, although the fraction of the most populated clusters is larger for P6E.
Collapse
Affiliation(s)
- Ian W Hamley
- Department of Chemistry, University of Reading, Whiteknights , Reading RG6 6AD, U.K
| | - Valeria Castelletto
- Department of Chemistry, University of Reading, Whiteknights , Reading RG6 6AD, U.K
| | - Ashkan Dehsorkhi
- Department of Chemistry, University of Reading, Whiteknights , Reading RG6 6AD, U.K
| | - Juan Torras
- Departament d'Enginyeria Química (EEBE) and Barcelona Research Center for Multiscale Science and Engineering, Universitat Politècnica de Catalunya , C/Eduard Maristany, 10-14, Ed. I2, 08019, Barcelona, Spain
| | - Carlos Aleman
- Departament d'Enginyeria Química (EEBE) and Barcelona Research Center for Multiscale Science and Engineering, Universitat Politècnica de Catalunya , C/Eduard Maristany, 10-14, Ed. I2, 08019, Barcelona, Spain
| | - Irina Portnaya
- Department of Biotechnology and Food Engineering and the Russell Berrie Nanotechnology Institute, Technion , Haifa, Israel 32000
| | - Dganit Danino
- Department of Biotechnology and Food Engineering and the Russell Berrie Nanotechnology Institute, Technion , Haifa, Israel 32000
| |
Collapse
|
42
|
Wang L, Coric P, Zhu K, Liu WQ, Vidal M, Bouaziz S, Broussy S. Synthesis and characterization of water-soluble macrocyclic peptides stabilizing protein α-turn. Org Biomol Chem 2018; 16:459-471. [DOI: 10.1039/c7ob02852k] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Macrocyclic peptides mimic tight “non-classical” α-turn type II-αLS found in proteins, as shown by spectroscopic and computational analysis of their equilibrating conformations.
Collapse
Affiliation(s)
- Lei Wang
- UMR COMETE 8638 CNRS
- Université Paris Descartes
- Faculté de Pharmacie de Paris
- Sorbonne Paris Cité
- Paris 75006
| | - Pascale Coric
- UMR 8015 CNRS
- Université Paris Descartes
- Faculté de Pharmacie de Paris
- Sorbonne Paris Cité
- Paris 75006
| | - Kexin Zhu
- UMR COMETE 8638 CNRS
- Université Paris Descartes
- Faculté de Pharmacie de Paris
- Sorbonne Paris Cité
- Paris 75006
| | - Wang-Qing Liu
- UMR COMETE 8638 CNRS
- Université Paris Descartes
- Faculté de Pharmacie de Paris
- Sorbonne Paris Cité
- Paris 75006
| | - Michel Vidal
- UMR COMETE 8638 CNRS
- Université Paris Descartes
- Faculté de Pharmacie de Paris
- Sorbonne Paris Cité
- Paris 75006
| | - Serge Bouaziz
- UMR 8015 CNRS
- Université Paris Descartes
- Faculté de Pharmacie de Paris
- Sorbonne Paris Cité
- Paris 75006
| | - Sylvain Broussy
- UMR COMETE 8638 CNRS
- Université Paris Descartes
- Faculté de Pharmacie de Paris
- Sorbonne Paris Cité
- Paris 75006
| |
Collapse
|
43
|
Biondi B, Peggion C, De Zotti M, Pignaffo C, Dalzini A, Bortolus M, Oancea S, Hilma G, Bortolotti A, Stella L, Pedersen JZ, Syryamina VN, Tsvetkov YD, Dzuba SA, Toniolo C, Formaggio F. Conformational properties, membrane interaction, and antibacterial activity of the peptaibiotic chalciporin A: Multitechnique spectroscopic and biophysical investigations on the natural compound and labeled analogs. Biopolymers 2017; 110. [PMID: 29127716 DOI: 10.1002/bip.23083] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 10/06/2017] [Accepted: 10/15/2017] [Indexed: 02/28/2024]
Abstract
In this work, an extensive set of spectroscopic and biophysical techniques (including FT-IR absorption, CD, 2D-NMR, fluorescence, and CW/PELDOR EPR) was used to study the conformational preferences, membrane interaction, and bioactivity properties of the naturally occurring synthetic 14-mer peptaibiotic chalciporin A, characterized by a relatively low (≈20%), uncommon proportion of the strongly helicogenic Aib residue. In addition to the unlabeled peptide, we gained in-depth information from the study of two labeled analogs, characterized by one or two residues of the helicogenic, nitroxyl radical-containing TOAC. All three compounds were prepared using the SPPS methodology, which was carefully modified in the course of the syntheses of TOAC-labeled analogs in view of the poorly reactive α-amino function of this very bulky residue and the specific requirements of its free-radical side chain. Despite its potentially high flexibility, our results point to a predominant, partly amphiphilic, α-helical conformation for this peptaibiotic. Therefore, not surprisingly, we found an effective membrane affinity and a remarkable penetration propensity. However, chalciporin A exhibits a selectivity in its antibacterial activity not in agreement with that typical of the other members of this peptide class.
Collapse
Affiliation(s)
- Barbara Biondi
- Institute of Biomolecular, Chemistry, Padova Unit, CNR, Padova, 35131, Italy
| | - Cristina Peggion
- Department of Chemical Sciences, University of Padova, Padova, 35131, Italy
| | - Marta De Zotti
- Department of Chemical Sciences, University of Padova, Padova, 35131, Italy
| | - Chiara Pignaffo
- Department of Chemical Sciences, University of Padova, Padova, 35131, Italy
| | - Annalisa Dalzini
- Department of Chemical Sciences, University of Padova, Padova, 35131, Italy
| | - Marco Bortolus
- Department of Chemical Sciences, University of Padova, Padova, 35131, Italy
| | - Simona Oancea
- Department of Agricultural Sciences and Food Engineering, "Lucian Blaga" University of Sibiu, Sibiu, 550012, Romania
| | - Geta Hilma
- Department of Medicine, "Lucian Blaga" University of Sibiu, Sibiu, 550012, Romania
| | - Annalisa Bortolotti
- Department of Chemical Sciences and Technologies, University of Rome Tor Vergata, Rome, 00133, Italy
| | - Lorenzo Stella
- Department of Chemical Sciences and Technologies, University of Rome Tor Vergata, Rome, 00133, Italy
| | - Jens Z Pedersen
- Department of Biology, University of Rome Tor Vergata, Rome, 00133, Italy
| | - Victoria N Syryamina
- Institute of Chemical Kinetics and Combustion, Novosibirsk, 630090, Russian Federation
| | - Yuri D Tsvetkov
- Institute of Chemical Kinetics and Combustion, Novosibirsk, 630090, Russian Federation
| | - Sergei A Dzuba
- Institute of Chemical Kinetics and Combustion, Novosibirsk, 630090, Russian Federation
| | - Claudio Toniolo
- Institute of Biomolecular, Chemistry, Padova Unit, CNR, Padova, 35131, Italy
- Department of Chemical Sciences, University of Padova, Padova, 35131, Italy
| | - Fernando Formaggio
- Institute of Biomolecular, Chemistry, Padova Unit, CNR, Padova, 35131, Italy
- Department of Chemical Sciences, University of Padova, Padova, 35131, Italy
| |
Collapse
|
44
|
Injectable silk fibroin hydrogels functionalized with microspheres as adult stem cells-carrier systems. Int J Biol Macromol 2017; 108:960-971. [PMID: 29113887 DOI: 10.1016/j.ijbiomac.2017.11.013] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 11/02/2017] [Accepted: 11/03/2017] [Indexed: 12/30/2022]
Abstract
Hydrogels are good candidate materials for cell delivery scaffolds because they can mimic the physical, chemical, electrical and biological properties of most of the native tissues. In this study, composite biosynthetic hydrogels were produced by combining the bio-functionality of silk fibroin (SF) with the structural versatility of polyethylene-glycol-diacrylated (PEGDa). The formation of a photopolymerizable PEGDa-SF hydrogel (PSFHy) was optimized for 3D-cell culture. Functionalization of the 3D-PSFHy with protein microspheres (MS) was required to increase the porosity and cell-adhesive properties of the material. Cardiac mesenchymal stem cells, which were cultured within the MS-embedding PSFHy, exhibited good viability and expression of proteins that are characteristic of the initial phases of the cardiac muscle differentiation process. Further, the addition of chondroitin sulfate into the scaffolds improved the cell viability. A cell-preconditioning of the scaffold was also performed, suggesting a potential application of these sponge-like scaffolds for analysing the effects of several extracellular microenvironments, produced by different kinds of cells, on the stem cells fate. The results presented herein highlight on the possibility to use the PSFHys functionalized with MS as stem cell-carrier systems with sponge-like properties, potential ultrasound-imaging contrast agents and controlled biochemical factor delivery.
Collapse
|
45
|
Banerjee R, Sheet T. Ratio of ellipticities between 192 and 208 nm (R 1 ): An effective electronic circular dichroism parameter for characterization of the helical components of proteins and peptides. Proteins 2017; 85:1975-1982. [PMID: 28707342 DOI: 10.1002/prot.25351] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 07/09/2017] [Accepted: 07/10/2017] [Indexed: 01/28/2023]
Abstract
Circular dichroism (CD) spectroscopy represents an important tool for characterization of the peptide and protein secondary structures that mainly arise from the conformational disposition of the peptide backbone in solution. In 1991 Manning and Woody proposed that, in addition to the signal intensity, the ratio between [θ]nπ* and [θ]ππ*ǁ ((R2 ) ≅ [θ]222 /[θ]208 ), along with [θ]ππ*⊥ and [θ]ππ*ǁ ((R1 ) ≅ [θ]192 /[θ]208 ), may be utilized towards identifying the peptide/protein conformation (especially 310 - and α-helices). However, till date the use of the ratiometric ellipticity component for helical structure analysis of peptides and proteins has not been reported. We studied a series of temperature dependent CD spectra of a thermally stable, model helical peptide and its related analogs in water as a function of added 2,2,2-trifluoroethanol (TFE) in order to explore their landscape of helicity. For the first time, we have experimentally shown here that the R1 parameter can characterize better the individual helices, while the other parameter R2 and the signal intensity do not always converge. We emphasize the use of the R1 ratio of ellipticities for helical characterization because of the common origin of these two bands (exciton splitting of the amide π→ π* transition in a helical polypeptide). This approach may become worthwhile and timely with the increasing accessibility of CD synchrotron sources.
Collapse
Affiliation(s)
- Raja Banerjee
- Maulana Abul Kalam Azad University of Technology, West Bengal (Formerly Known as West Bengal University of Technology), Salt Lake, Kolkata, 700064, West Bengal, India
| | - Tridip Sheet
- Maulana Abul Kalam Azad University of Technology, West Bengal (Formerly Known as West Bengal University of Technology), Salt Lake, Kolkata, 700064, West Bengal, India
| |
Collapse
|
46
|
T PL, Mondal M, Ramadas K, Natarajan S. Molecular interaction of 2,4-diacetylphloroglucinol (DAPG) with human serum albumin (HSA): The spectroscopic, calorimetric and computational investigation. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2017; 183:90-102. [PMID: 28441541 DOI: 10.1016/j.saa.2017.04.012] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 03/29/2017] [Accepted: 04/14/2017] [Indexed: 06/07/2023]
Abstract
Drug molecule interaction with human serum albumin (HSA) affects the distribution and elimination of the drug. The compound, 2,4-diacetylphloroglucinol (DAPG) has been known for its antimicrobial, antiviral, antihelminthic and anticancer properties. However, its interaction with HSA is not yet reported. In this study, the interaction between HSA and DAPG was investigated through steady-state fluorescence, time-resolved fluorescence (TRF), circular dichroism (CD), Fourier transform infrared (FT-IR) spectroscopy, isothermal titration calorimetry (ITC), molecular docking and molecular dynamics simulation (MDS). Fluorescence spectroscopy results showed the strong quenching of intrinsic fluorescence of HSA due to interaction with DAPG, through dynamic quenching mechanism. The compound bound to HSA with reversible and moderate affinity which explained its easy diffusion from circulatory system to target tissue. The thermodynamic parameters from fluorescence spectroscopic data clearly revealed the contribution of hydrophobic forces but, the role of hydrogen bonds was not negligible according to the ITC studies. The interaction was exothermic and spontaneous in nature. Binding with DAPG reduced the helical content of protein suggesting the unfolding of HSA. Site marker fluorescence experiments revealed the change in binding constant of DAPG in the presence of site I (warfarin) but not site II marker (ibuprofen) which confirmed that the DAPG bound to site I. ITC experiments also supported this as site I marker could not bind to HSA-DAPG complex while site II marker was accommodated in the complex. In silico studies further showed the lowest binding affinity and more stability of DAPG in site I than in site II. Thus the data presented in this study confirms the binding of DAPG to the site I of HSA which may help in further understanding of pharmacokinetic properties of DAPG.
Collapse
Affiliation(s)
- Pragna Lakshmi T
- Centre for Bioinformatics, Pondicherry University, Pondicherry, India
| | - Moumita Mondal
- Department of Biotechnology, Pondicherry University, Pondicherry, India
| | - Krishna Ramadas
- Centre for Bioinformatics, Pondicherry University, Pondicherry, India.
| | | |
Collapse
|
47
|
Wang X, Junior JCB, Mishra B, Lushnikova T, Epand RM, Wang G. Arginine-lysine positional swap of the LL-37 peptides reveals evolutional advantages of the native sequence and leads to bacterial probes. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2017; 1859:1350-1361. [PMID: 28450045 PMCID: PMC5516960 DOI: 10.1016/j.bbamem.2017.04.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Revised: 04/14/2017] [Accepted: 04/19/2017] [Indexed: 10/19/2022]
Abstract
Antimicrobial peptides are essential components of the innate immune system of multicellular organisms. Although cationic and hydrophobic amino acids are known determinants of these amphipathic molecules for bacterial killing, it is not clear how lysine-arginine (K-R) positional swaps influence peptide structure and activity. This study addresses this question by investigating two groups of peptides (GF-17 and 17BIPHE2) derived from human cathelicidin LL-37. K-R positional swap showed little effect on minimal inhibitory concentrations of the peptides. However, there are clear differences in bacterial killing kinetics. The membrane permeation patterns vary with peptide and bacterial types, but not changes in fluorescent dyes, salts or pH. In general, the original peptide is more efficient in bacterial killing, but less toxic to human cells, than the K-R swapped peptides, revealing the evolutionary significance of the native sequence for host defense. The characteristic membrane permeation patterns for different bacteria suggest a possible application of these K-R positional-swapped peptides as molecular probes for the type of bacteria. Such differences are related to bacterial membrane compositions: minimal for Gram-positive Staphylococcus aureus with essentially all anionic lipids (cardiolipin and phosphatidylglycerol), but evident for Gram-negative Klebsiella pneumoniae, Pseudomonas aeruginosa and Escherichia coli with a mixture of phosphatidylethanolamine and phosphatidylglycerol. Biophysical characterization found similar structures and binding affinities for these peptides in vesicle systems mimicking E. coli and S. aureus. It seems that interfacial arginines of GF-17 are preferred over lysines in bacterial membrane permeation. Our study sheds new light on the design of cationic amphipathic peptides.
Collapse
Affiliation(s)
- Xiuqing Wang
- Department of Pathology and Microbiology, University of Nebraska Medical Center, 986495 Nebraska Medical Center, Omaha, NE 68198-6495, USA; Department of Surgery, General Hospital of Ningxia Medical University, Yinchuan 750004, China
| | - José Carlos Bozelli Junior
- Department of Biochemistry and Biomedical Sciences, McMaster University, Health Sciences Centre, Hamilton, Ontario L8S 4K1, Canada
| | - Biswajit Mishra
- Department of Pathology and Microbiology, University of Nebraska Medical Center, 986495 Nebraska Medical Center, Omaha, NE 68198-6495, USA
| | - Tamara Lushnikova
- Department of Pathology and Microbiology, University of Nebraska Medical Center, 986495 Nebraska Medical Center, Omaha, NE 68198-6495, USA
| | - Richard M Epand
- Department of Biochemistry and Biomedical Sciences, McMaster University, Health Sciences Centre, Hamilton, Ontario L8S 4K1, Canada
| | - Guangshun Wang
- Department of Pathology and Microbiology, University of Nebraska Medical Center, 986495 Nebraska Medical Center, Omaha, NE 68198-6495, USA.
| |
Collapse
|
48
|
Marafon G, Menegazzo I, De Zotti M, Crisma M, Toniolo C, Moretto A. Tuning morphological architectures generated through living supramolecular assembly of a helical foldamer end-capped with two complementary nucleobases. SOFT MATTER 2017; 13:4231-4240. [PMID: 28509927 DOI: 10.1039/c7sm00764g] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Two appropriately functionalized nucleobases, thymine and adenine, have been covalently linked at the N- and C-termini, respectively, of two α-aminoisobutyric acid-rich helical peptide foldamers, aiming at driving self-assembly through complementary recognition. A crystal-state analysis (by X-ray diffraction) on the shorter, achiral foldamer 1 unambiguously shows that adeninethymine base pairing, through Watson-Crick intermolecular H-bonding, does take place between either end of each peptide molecule. In the crystals, π-stacking between base pairs is also observed. Evidence for time-dependent foldameroldamer associations for the longer, chiral foldamer 2 in solution is provided by circular dichroism measurements. The self-assembly of foldamer 2, through living supramolecular polymerization, eventually leads to the formation of twisted fibers. Such a supramolecular organization can be affected by addition of either pristine adenine or thymine, that acts as a "terminator" by selectively matching a pairing nucleobase at one end of the foldamer. The co-assembly of foldamer 2 with a porphyrin-derivatized thymine, under appropriate experimental conditions, leads to the formation of vesicles which, in turn, can be converted to the fiber morphology by changing the environmental polarity. Conversely, dendrimeric, star polymer-like microstructures are generated when the supramolecular assembly of foldamer 2 is seeded by adenine-capped gold nanoparticles.
Collapse
Affiliation(s)
- Giulia Marafon
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy.
| | | | | | | | | | | |
Collapse
|
49
|
Hendus-Altenburger R, Lambrughi M, Terkelsen T, Pedersen SF, Papaleo E, Lindorff-Larsen K, Kragelund BB. A phosphorylation-motif for tuneable helix stabilisation in intrinsically disordered proteins - Lessons from the sodium proton exchanger 1 (NHE1). Cell Signal 2017; 37:40-51. [PMID: 28554535 DOI: 10.1016/j.cellsig.2017.05.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 05/24/2017] [Accepted: 05/25/2017] [Indexed: 11/26/2022]
Abstract
Intrinsically disordered proteins (IDPs) are involved in many pivotal cellular processes including phosphorylation and signalling. The structural and functional effects of phosphorylation of IDPs remain poorly understood and difficult to predict. Thus, a need exists to identify motifs that confer phosphorylation-dependent perturbation of the local preferences for forming e.g. helical structures as well as motifs that do not. The disordered distal tail of the Na+/H+ exchanger 1 (NHE1) is six-times phosphorylated (S693, S723, S726, S771, T779, S785) by the mitogen activated protein kinase 2 (MAPK1, ERK2). Using NMR spectroscopy, we found that two out of those six phosphorylation sites had a stabilizing effect on transient helices. One of these was further investigated by circular dichroism and NMR spectroscopy as well as by molecular dynamic simulations, which confirmed the stabilizing effect and resulted in the identification of a short linear motif for helix stabilisation: [S/T]-P-{3}-[R/K] where [S/T] is the phosphorylation-site. By analysing IDP and phosphorylation site databases we found that the motif is significantly enriched around known phosphorylation sites, supporting a potential wider-spread role in phosphorylation-mediated regulation of intrinsically disordered proteins. The identification of such motifs is important for understanding the molecular mechanism of cellular signalling, and is crucial for the development of predictors for the structural effect of phosphorylation; a tool of relevance for understanding disease-promoting mutations that for example interfere with signalling for instance through constitutive active and often cancer-promoting signalling.
Collapse
Affiliation(s)
- Ruth Hendus-Altenburger
- Structural Biology and NMR Laboratory, Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark.
| | - Matteo Lambrughi
- Computational Biology Laboratory, Center for Autophagy, Recycling and Disease, Strandboulevarden 49, 2100 Copenhagen, Denmark.
| | - Thilde Terkelsen
- Computational Biology Laboratory, Center for Autophagy, Recycling and Disease, Strandboulevarden 49, 2100 Copenhagen, Denmark.
| | - Stine F Pedersen
- Cell Biology and Physiology, Department of Biology, University of Copenhagen, Universitetsparken 13, DK-2100 Copenhagen Ø, Denmark.
| | - Elena Papaleo
- Computational Biology Laboratory, Center for Autophagy, Recycling and Disease, Strandboulevarden 49, 2100 Copenhagen, Denmark.
| | - Kresten Lindorff-Larsen
- Structural Biology and NMR Laboratory, Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark.
| | - Birthe B Kragelund
- Structural Biology and NMR Laboratory, Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark.
| |
Collapse
|
50
|
Goyal B, Srivastava KR, Durani S. N-terminal diproline and charge group effects on the stabilization of helical conformation in alanine-based short peptides: CD studies with water and methanol as solvent. J Pept Sci 2017; 23:431-437. [PMID: 28425159 DOI: 10.1002/psc.3005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 03/17/2017] [Accepted: 03/20/2017] [Indexed: 12/25/2022]
Abstract
Protein folding problem remains a formidable challenge as main chain, side chain and solvent interactions remain entangled and have been difficult to resolve. Alanine-based short peptides are promising models to dissect protein folding initiation and propagation structurally as well as energetically. The effect of N-terminal diproline and charged side chains is assessed on the stabilization of helical conformation in alanine-based short peptides using circular dichroism (CD) with water and methanol as solvent. A1 (Ac-Pro-Pro-Ala-Lys-Ala-Lys-Ala-Lys-Ala-NH2 ) is designed to assess the effect of N-terminal homochiral diproline and lysine side chains to induce helical conformation. A2 (Ac-Pro-Pro-Glu-Glu-Ala-Ala-Lys-Lys-Ala-NH2 ) and A3 (Ac-dPro-Pro-Glu-Glu-Ala-Ala-Lys-Lys-Ala-NH2 ) with N-terminal homochiral and heterochiral diproline, respectively, are designed to assess the effect of Glu...Lys (i, i + 4) salt bridge interactions on the stabilization of helical conformation. The CD spectra of A1, A2 and A3 in water manifest different amplitudes of the observed polyproline II (PPII) signals, which indicate different conformational distributions of the polypeptide structure. The strong effect of solvent substitution from water to methanol is observed for the peptides, and CD spectra in methanol evidence A2 and A3 as helical folds. Temperature-dependent CD spectra of A1 and A2 in water depict an isodichroic point reflecting coexistence of two conformations, PPII and β-strand conformation, which is consistent with the previous studies. The results illuminate the effect of N-terminal diproline and charged side chains in dictating the preferences for extended-β, semi-extended PPII and helical conformation in alanine-based short peptides. The results of the present study will enhance our understanding on stabilization of helical conformation in short peptides and hence aid in the design of novel peptides with helical structures. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.
Collapse
Affiliation(s)
- Bhupesh Goyal
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.,Department of Chemistry, School of Basic and Applied Sciences, Sri Guru Granth Sahib World University, Fatehgarh Sahib, 140406, Punjab, India
| | - Kinshuk Raj Srivastava
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.,Life Sciences Institute, University of Michigan, Ann Arbor, MI, 48105, USA
| | - Susheel Durani
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| |
Collapse
|