1
|
Leinberger FH, Berghoff BA. Relevance of charged and polar amino acids for functionality of membrane toxin TisB. Sci Rep 2024; 14:22998. [PMID: 39362964 PMCID: PMC11449926 DOI: 10.1038/s41598-024-73879-7] [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: 07/12/2024] [Accepted: 09/23/2024] [Indexed: 10/05/2024] Open
Abstract
Bacterial dormancy is marked by reduced cellular activity and the suspension of growth. It represents a valuable strategy to survive stressful conditions, as exemplified by the long-term tolerance towards antibiotics that is attributable to a fraction of dormant cells, so-called persisters. Here, we investigate the membrane toxin TisB (29 amino acids) from the chromosomal toxin-antitoxin system tisB/istR-1 in Escherichia coli. TisB depolarizes the inner membrane in response to DNA damage, which eventually promotes a stress-tolerant state of dormancy within a small fraction of the population. Using a plasmid-based system for moderate tisB expression and single amino acid substitutions, we dissect the importance of charged and polar amino acids. We observe that the central amino acids lysine 12 and glutamine 19 are of major importance for TisB functionality, which is further validated for lysine 12 in the native context upon treatment with the DNA-damaging antibiotic ciprofloxacin. Finally, we apply a library-based approach to test additional TisB variants in higher throughput, revealing that at least one positive charge at the C-terminus (either lysine 26 or 29) is mandatory for TisB-mediated dormancy. Our study provides insights into the molecular basis for TisB functionality and extends our understanding of bacterial membrane toxins.
Collapse
Affiliation(s)
- Florian H Leinberger
- Institute for Microbiology and Molecular Biology, Justus Liebig University Giessen, 35392, Giessen, Germany
| | - Bork A Berghoff
- Institute for Microbiology and Molecular Biology, Justus Liebig University Giessen, 35392, Giessen, Germany.
- Institute of Molecular Biology and Biotechnology of Prokaryotes, University of Ulm, 89069, Ulm, Germany.
| |
Collapse
|
2
|
Shore SFH, Leinberger FH, Fozo EM, Berghoff BA. Type I toxin-antitoxin systems in bacteria: from regulation to biological functions. EcoSal Plus 2024:eesp00252022. [PMID: 38767346 DOI: 10.1128/ecosalplus.esp-0025-2022] [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: 09/29/2023] [Accepted: 04/11/2024] [Indexed: 05/22/2024]
Abstract
Toxin-antitoxin systems are ubiquitous in the prokaryotic world and widely distributed among chromosomes and mobile genetic elements. Several different toxin-antitoxin system types exist, but what they all have in common is that toxin activity is prevented by the cognate antitoxin. In type I toxin-antitoxin systems, toxin production is controlled by an RNA antitoxin and by structural features inherent to the toxin messenger RNA. Most type I toxins are small membrane proteins that display a variety of cellular effects. While originally discovered as modules that stabilize plasmids, chromosomal type I toxin-antitoxin systems may also stabilize prophages, or serve important functions upon certain stress conditions and contribute to population-wide survival strategies. Here, we will describe the intricate RNA-based regulation of type I toxin-antitoxin systems and discuss their potential biological functions.
Collapse
Affiliation(s)
- Selene F H Shore
- Department of Microbiology, University of Tennessee, Knoxville, Tennessee, USA
| | - Florian H Leinberger
- Institute for Microbiology and Molecular Biology, Justus-Liebig University, Giessen, Germany
| | - Elizabeth M Fozo
- Department of Microbiology, University of Tennessee, Knoxville, Tennessee, USA
| | - Bork A Berghoff
- Institute for Microbiology and Molecular Biology, Justus-Liebig University, Giessen, Germany
| |
Collapse
|
3
|
Bellanger T, da Silva Barreira D, Wien F, Delarue P, Senet P, Rieu A, Neiers F, Varela PF, Combet S, Weidmann S. Significant influence of four highly conserved amino-acids in lipochaperon-active sHsps on the structure and functions of the Lo18 protein. Sci Rep 2023; 13:19036. [PMID: 37923897 PMCID: PMC10624808 DOI: 10.1038/s41598-023-46306-6] [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: 09/08/2023] [Accepted: 10/30/2023] [Indexed: 11/06/2023] Open
Abstract
To cope with environmental stresses, bacteria have developed different strategies, including the production of small heat shock proteins (sHSP). All sHSPs are described for their role as molecular chaperones. Some of them, like the Lo18 protein synthesized by Oenococcus oeni, also have the particularity of acting as a lipochaperon to maintain membrane fluidity in its optimal state following cellular stresses. Lipochaperon activity is poorly characterized and very little information is available on the domains or amino-acids key to this activity. The aim in this paper is to investigate the importance at the protein structure and function level of four highly conserved residues in sHSP exhibiting lipochaperon activity. Thus, by combining in silico, in vitro and in vivo approaches the importance of three amino-acids present in the core of the protein was shown to maintain both the structure of Lo18 and its functions.
Collapse
Affiliation(s)
- Tiffany Bellanger
- Procédés Alimentaires et Microbiologiques (PAM), AgroSup Dijon, PAM UMR A 02.102, Laboratoire VAlMiS-IUVV, Dijon, France
| | - David da Silva Barreira
- Procédés Alimentaires et Microbiologiques (PAM), AgroSup Dijon, PAM UMR A 02.102, Laboratoire VAlMiS-IUVV, Dijon, France
| | - Frank Wien
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin BP 48, 91192, Gif-sur-Yvette, France
| | - Patrice Delarue
- Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303, CNRS, Université de Bourgogne Franche-Comté, 21078, Dijon, France
| | - Patrick Senet
- Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303, CNRS, Université de Bourgogne Franche-Comté, 21078, Dijon, France
| | - Aurélie Rieu
- Procédés Alimentaires et Microbiologiques (PAM), AgroSup Dijon, PAM UMR A 02.102, Laboratoire VAlMiS-IUVV, Dijon, France
| | - Fabrice Neiers
- Laboratory: Flavour Perception: Molecular Mechanisms (Flavours), INRAE, CNRS, Institut Agro, Université de Bourgogne Franche-Comté, 21000, Dijon, France
| | - Paloma Fernández Varela
- CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, 91198, Gif-sur-Yvette, France
| | - Sophie Combet
- Laboratoire Léon-Brillouin (LLB), UMR12 CEA, CNRS, Université Paris-Saclay, 91191, Gif-sur-Yvette CEDEX, France
| | - Stéphanie Weidmann
- Procédés Alimentaires et Microbiologiques (PAM), AgroSup Dijon, PAM UMR A 02.102, Laboratoire VAlMiS-IUVV, Dijon, France.
| |
Collapse
|
4
|
Fermon L, Burel A, Ostyn E, Dréano S, Bondon A, Chevance S, Pinel-Marie ML. Mechanism of action of sprG1-encoded type I toxins in Staphylococcus aureus: from membrane alterations to mesosome-like structures formation and bacterial lysis. Front Microbiol 2023; 14:1275849. [PMID: 37854335 PMCID: PMC10579593 DOI: 10.3389/fmicb.2023.1275849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 09/11/2023] [Indexed: 10/20/2023] Open
Abstract
sprG1/SprF1 is a type I toxin-antitoxin system located on Staphylococcus aureus prophage. It has previously been shown that the two toxins, SprG131 and SprG144, encoded by the sprG1 gene, are two membrane-associated peptides structured in a single α-helix. Overexpression of these two peptides leads to growth inhibition and even S. aureus death. In this study, we investigated the involvement of each peptide in this toxicity, the sequence requirements necessary for SprG131 toxicity, and the mechanism of action of these two peptides. Our findings show that both peptides, when expressed individually, are able to stop growth, with higher toxicity observed for SprG131. The combination of a hydrophobic domain and a charged domain located only at the C-terminus is necessary for this toxicity, likely to retain the orientation of the transmembrane domain. A net cationic charge for SprG131 is not essential to induce a growth defect in S. aureus. Furthermore, we established a chronology of toxic events following overexpression to gain insights into the mode of action of SprG144 and SprG131. We demonstrated that mesosome-like structures are already formed when membrane is depolarized, about 20 min after peptides induction. This membrane depolarization occurs concomitantly with a depletion of intracellular ATP, leading to S. aureus growth arrest. Moreover, we hypothesized that SprG144 and SprG131 do not form large pores in the S. aureus membrane, as ATP is not excreted into the extracellular medium, and membrane permeabilization is delayed relative to membrane depolarization. The next challenge is to identify the conditions under which SprG144 and SprG131 are naturally expressed, and to uncover their potential roles during staphylococcal growth, colonization, and infection.
Collapse
Affiliation(s)
- Laurence Fermon
- Univ Rennes, INSERM, BRM – UMR_S 1230, Rennes, France
- Univ Rennes, CNRS, ISCR – UMR 6226, Rennes, France
| | - Agnès Burel
- Univ Rennes, CNRS, INSERM, BIOSIT – UAR 3480, US_S 018, Rennes, France
| | - Emeline Ostyn
- Univ Rennes, INSERM, BRM – UMR_S 1230, Rennes, France
| | | | | | | | | |
Collapse
|
5
|
Cao Z, Zhao L, Yan T, Liu L. Effects of C-Terminal Lys-Arg Residue of AapA1 Protein on Toxicity and Structural Mechanism. Toxins (Basel) 2023; 15:542. [PMID: 37755968 PMCID: PMC10537873 DOI: 10.3390/toxins15090542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 08/30/2023] [Accepted: 08/31/2023] [Indexed: 09/28/2023] Open
Abstract
Previous experimental investigations have established the indispensability of the C-terminal Lys-Arg residues in the toxic activity of the AapA1 toxin protein. AapA1 is classified as a type I toxin-antitoxin (TA) bacterial toxin, and the precise impact of the C-terminal Lys-Arg residues on its structure and mechanism of action remains elusive. To address this knowledge gap, the present study employed molecular dynamics (MD) and enhanced sampling Well-tempered Two-dimensional Metadynamics (2D-MetaD) simulations to examine the behavior of the C-terminal Lys-Arg residues of truncated AapA1 toxin (AapA1-28) within the inner membrane of Escherichia coli. Specifically, the study focused on the elucidation of possible conformation states of AapA1-28 protein in POPE/POPG (3:1) bilayers and their interactions between the protein and POPE/POPG (3:1) bilayers. The findings of our investigation indicate that the AapA1-28 protein does not adopt a vertical orientation upon membrane insertion; rather, it assumes an angled conformation, with the side chain of Lys-23 directed toward the upper layer of the membrane. This non-transmembrane conformation of AapA1-28 protein impedes its ability to form pores within the membrane, resulting in reduced toxicity towards Escherichia coli. These results suggest that C-Terminal positively charged residues are essential for electrostatic binding to the negatively charged head group of bottom bilayer membrane, which stabilize the transmembrane conformation. These outcomes contribute to our comprehension of the impact of C-terminal charged residues on the structure and functionality of membrane-associated proteins, and provide an improved understanding of how protein sequence influences the antimicrobial effect.
Collapse
Affiliation(s)
- Zanxia Cao
- Shandong Provincial Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou 253023, China; (L.Z.); (T.Y.)
| | - Liling Zhao
- Shandong Provincial Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou 253023, China; (L.Z.); (T.Y.)
- College of Physics and Electronic Information, Dezhou University, Dezhou 253023, China
| | - Tingting Yan
- Shandong Provincial Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou 253023, China; (L.Z.); (T.Y.)
| | - Lei Liu
- Shandong Provincial Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou 253023, China; (L.Z.); (T.Y.)
| |
Collapse
|
6
|
Espeche JC, Varas R, Maturana P, Cutro AC, Maffía PC, Hollmann A. Membrane permeability and antimicrobial peptides: Much more than just making a hole. Pept Sci (Hoboken) 2023. [DOI: 10.1002/pep2.24305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023]
|
7
|
Bogati B, Shore SFH, Nipper TD, Stoiculescu O, Fozo EM. Charged Amino Acids Contribute to ZorO Toxicity. Toxins (Basel) 2022; 15:32. [PMID: 36668852 PMCID: PMC9860968 DOI: 10.3390/toxins15010032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 12/24/2022] [Accepted: 12/27/2022] [Indexed: 01/03/2023] Open
Abstract
Chromosomally encoded toxin-antitoxin systems have been increasingly identified and characterized across bacterial species over the past two decades. Overproduction of the toxin gene results in cell growth stasis or death for the producing cell, but co-expression of its antitoxin can repress the toxic effects. For the subcategory of type I toxin-antitoxin systems, many of the described toxin genes encode a small, hydrophobic protein with several charged residues distributed across the sequence of the toxic protein. Though these charged residues are hypothesized to be critical for the toxic effects of the protein, they have not been studied broadly across different type I toxins. Herein, we mutated codons encoding charged residues in the type I toxin zorO, from the zor-orz toxin-antitoxin system, to determine their impacts on growth inhibition, membrane depolarization, ATP depletion, and the localization of this small protein. The non-toxic variants of ZorO accumulated both in the membrane and cytoplasm, indicating that membrane localization alone is not sufficient for its toxicity. While mutation of a charged residue could result in altered toxicity, this was dependent not only on the position of the amino acid within the protein but also on the residue to which it was converted, suggesting a complex role of charged residues in ZorO-mediated toxicity. A previous study indicated that additional copies of the zor-orz system improved growth in aminoglycosides: within, we note that this improved growth is independent of ZorO toxicity. By increasing the copy number of the zorO gene fused with a FLAG-tag, we were able to detect the protein expressed from its native promoter elements: an important step for future studies of toxin expression and function.
Collapse
Affiliation(s)
| | | | | | | | - Elizabeth M. Fozo
- Department of Microbiology, University of Tennessee Knoxville, Knoxville, TN 37996, USA
| |
Collapse
|
8
|
Membranolytic Mechanism of Amphiphilic Antimicrobial β-Stranded [KL]n Peptides. Biomedicines 2022; 10:biomedicines10092071. [PMID: 36140173 PMCID: PMC9495826 DOI: 10.3390/biomedicines10092071] [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: 07/26/2022] [Revised: 08/19/2022] [Accepted: 08/21/2022] [Indexed: 11/17/2022] Open
Abstract
Amphipathic peptides can act as antibiotics due to membrane permeabilization. KL peptides with the repetitive sequence [Lys-Leu]n-NH2 form amphipathic β-strands in the presence of lipid bilayers. As they are known to kill bacteria in a peculiar length-dependent manner, we suggest here several different functional models, all of which seem plausible, including a carpet mechanism, a β-barrel pore, a toroidal wormhole, and a β-helix. To resolve their genuine mechanism, the activity of KL peptides with lengths from 6–26 amino acids (plus some inverted LK analogues) was systematically tested against bacteria and erythrocytes. Vesicle leakage assays served to correlate bilayer thickness and peptide length and to examine the role of membrane curvature and putative pore diameter. KL peptides with 10–12 amino acids showed the best therapeutic potential, i.e., high antimicrobial activity and low hemolytic side effects. Mechanistically, this particular window of an optimum β-strand length around 4 nm (11 amino acids × 3.7 Å) would match the typical thickness of a lipid bilayer, implying the formation of a transmembrane pore. Solid-state 15N- and 19F-NMR structure analysis, however, showed that the KL backbone lies flat on the membrane surface under all conditions. We can thus refute any of the pore models and conclude that the KL peptides rather disrupt membranes by a carpet mechanism. The intriguing length-dependent optimum in activity can be fully explained by two counteracting effects, i.e., membrane binding versus amyloid formation. Very short KL peptides are inactive, because they are unable to bind to the lipid bilayer as flexible β-strands, whereas very long peptides are inactive due to vigorous pre-aggregation into β-sheets in solution.
Collapse
|
9
|
Gössweiner-Mohr N, Siligan C, Pluhackova K, Umlandt L, Koefler S, Trajkovska N, Horner A. The Hidden Intricacies of Aquaporins: Remarkable Details in a Common Structural Scaffold. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2202056. [PMID: 35802902 DOI: 10.1002/smll.202202056] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 06/09/2022] [Indexed: 06/15/2023]
Abstract
Evolution turned aquaporins (AQPs) into the most efficient facilitators of passive water flow through cell membranes at no expense of solute discrimination. In spite of a plethora of solved AQP structures, many structural details remain hidden. Here, by combining extensive sequence- and structural-based analysis of a unique set of 20 non-redundant high-resolution structures and molecular dynamics simulations of four representatives, key aspects of AQP stability, gating, selectivity, pore geometry, and oligomerization, with a potential impact on channel functionality, are identified. The general view of AQPs possessing a continuous open water pore is challenged and it is depicted that AQPs' selectivity is not exclusively shaped by pore-lining residues but also by the relative arrangement of transmembrane helices. Moreover, this analysis reveals that hydrophobic interactions constitute the main determinant of protein thermal stability. Finally, a numbering scheme of the conserved AQP scaffold is established, facilitating direct comparison of, for example, disease-causing mutations and prediction of potential structural consequences. Additionally, the results pave the way for the design of optimized AQP water channels to be utilized in biotechnological applications.
Collapse
Affiliation(s)
| | - Christine Siligan
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstr. 40, Linz, 4020, Austria
| | - Kristyna Pluhackova
- Stuttgart Center for Simulation Science, University of Stuttgart, Cluster of Excellence EXC 2075, Universitätsstr. 32, 70569, Stuttgart, Germany
| | - Linnea Umlandt
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstr. 40, Linz, 4020, Austria
| | - Sabina Koefler
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstr. 40, Linz, 4020, Austria
| | - Natasha Trajkovska
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstr. 40, Linz, 4020, Austria
| | - Andreas Horner
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstr. 40, Linz, 4020, Austria
| |
Collapse
|
10
|
Nonin-Lecomte S, Fermon L, Felden B, Pinel-Marie ML. Bacterial Type I Toxins: Folding and Membrane Interactions. Toxins (Basel) 2021; 13:toxins13070490. [PMID: 34357962 PMCID: PMC8309996 DOI: 10.3390/toxins13070490] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 07/08/2021] [Accepted: 07/09/2021] [Indexed: 11/16/2022] Open
Abstract
Bacterial type I toxin-antitoxin systems are two-component genetic modules that encode a stable toxic protein whose ectopic overexpression can lead to growth arrest or cell death, and an unstable RNA antitoxin that inhibits toxin translation during growth. These systems are widely spread among bacterial species. Type I antitoxins are cis- or trans-encoded antisense small RNAs that interact with toxin-encoding mRNAs by pairing, thereby inhibiting toxin mRNA translation and/or inducing its degradation. Under environmental stress conditions, the up-regulation of the toxin and/or the antitoxin degradation by specific RNases promote toxin translation. Most type I toxins are small hydrophobic peptides with a predicted α-helical transmembrane domain that induces membrane depolarization and/or permeabilization followed by a decrease of intracellular ATP, leading to plasmid maintenance, growth adaptation to environmental stresses, or persister cell formation. In this review, we describe the current state of the art on the folding and the membrane interactions of these membrane-associated type I toxins from either Gram-negative or Gram-positive bacteria and establish a chronology of their toxic effects on the bacterial cell. This review also includes novel structural results obtained by NMR concerning the sprG1-encoded membrane peptides that belong to the sprG1/SprF1 type I TA system expressed in Staphylococcus aureus and discusses the putative membrane interactions allowing the lysis of competing bacteria and host cells.
Collapse
Affiliation(s)
| | - Laurence Fermon
- BRM (Bacterial Regulatory RNAs and Medicine), Inserm, UMR_S 1230, Université de Rennes 1, 35000 Rennes, France; (L.F.); (B.F.)
| | - Brice Felden
- BRM (Bacterial Regulatory RNAs and Medicine), Inserm, UMR_S 1230, Université de Rennes 1, 35000 Rennes, France; (L.F.); (B.F.)
| | - Marie-Laure Pinel-Marie
- BRM (Bacterial Regulatory RNAs and Medicine), Inserm, UMR_S 1230, Université de Rennes 1, 35000 Rennes, France; (L.F.); (B.F.)
- Correspondence:
| |
Collapse
|
11
|
Ortiz-Padilla M, Diaz-Diaz S, Machuca J, Tejada-Gonzalez A, Recacha E, Docobo-Pérez F, Pascual A, Rodríguez-Martínez JM. Role of low-level quinolone resistance in generating tolerance in Escherichia coli under therapeutic concentrations of ciprofloxacin. J Antimicrob Chemother 2021; 75:2124-2132. [PMID: 32427318 DOI: 10.1093/jac/dkaa151] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 03/13/2020] [Accepted: 03/26/2020] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND Tolerance (including persistence) and resistance result in increased survival under antibiotic pressure. OBJECTIVES We evaluated the interplay between resistance and tolerance to ciprofloxacin under therapeutic and killing conditions to determine the contribution of low-level quinolone resistance (LLQR) mechanisms to tolerance. We also determined how the interaction between resistance (LLQR phenotypes) and tolerance was modified under SOS response suppression. METHODS Twelve isogenic Escherichia coli strains harbouring quinolone resistance mechanisms combined with SOS response deficiency and six clinical E. coli isolates (LLQR or non-LLQR) were evaluated. Survival (tolerance or persistence) assays were used to measure surviving bacteria after a short period (up to 4 h) of bactericidal antibiotic treatment under therapeutic and killing concentrations of ciprofloxacin [1 mg/L, EUCAST/CLSI breakpoint for resistance; and 2.5 mg/L, peak serum concentration (Cmax) of this drug]. RESULTS QRDR substitutions (S83L in GyrA alone or combined with S80R in ParC) significantly increased the fraction of tolerant bacteria (2-4 log10 cfu/mL) after exposure to ciprofloxacin at clinically relevant concentrations. The impact on tolerant bacteria due to SOS response suppression (including persistence mediated by the tisB gene) was reversed by LLQR mechanisms at therapeutic concentrations. Furthermore, no reduction in the fraction of tolerant bacteria due to SOS response suppression was observed when S83L in GyrA plus S80R in ParC were combined. CONCLUSIONS Tolerance and quinolone resistance mutations interact synergistically, giving LLQR mechanisms an additional role in allowing bacterial survival and evasion of therapeutic antimicrobial conditions by a combination of the two strategies. At clinically relevant concentrations, LLQR mechanisms reverse further impact of SOS response suppression in reducing bacterial tolerance.
Collapse
Affiliation(s)
- M Ortiz-Padilla
- Unidad Clínica de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospital Universitario Virgen Macarena, Seville, Spain.,Departamento de Microbiología, Facultad de Medicina, Universidad de Sevilla, Sevilla, Spain.,Red Española de Investigación en Patología Infecciosa (REIPI), Instituto de Salud Carlos III, Madrid, Spain.,Instituto de Biomedicina de Sevilla IBIS, Hospital Universitario Virgen Macarena/CSIC/Departamento de Microbiología, Universidad de Sevilla, Seville, Spain
| | - S Diaz-Diaz
- Unidad Clínica de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospital Universitario Virgen Macarena, Seville, Spain.,Departamento de Microbiología, Facultad de Medicina, Universidad de Sevilla, Sevilla, Spain.,Red Española de Investigación en Patología Infecciosa (REIPI), Instituto de Salud Carlos III, Madrid, Spain.,Instituto de Biomedicina de Sevilla IBIS, Hospital Universitario Virgen Macarena/CSIC/Departamento de Microbiología, Universidad de Sevilla, Seville, Spain
| | - J Machuca
- Unidad Clínica de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospital Universitario Virgen Macarena, Seville, Spain.,Departamento de Microbiología, Facultad de Medicina, Universidad de Sevilla, Sevilla, Spain.,Red Española de Investigación en Patología Infecciosa (REIPI), Instituto de Salud Carlos III, Madrid, Spain.,Instituto de Biomedicina de Sevilla IBIS, Hospital Universitario Virgen Macarena/CSIC/Departamento de Microbiología, Universidad de Sevilla, Seville, Spain
| | - A Tejada-Gonzalez
- Departamento de Microbiología, Facultad de Medicina, Universidad de Sevilla, Sevilla, Spain
| | - E Recacha
- Unidad Clínica de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospital Universitario Virgen Macarena, Seville, Spain.,Red Española de Investigación en Patología Infecciosa (REIPI), Instituto de Salud Carlos III, Madrid, Spain.,Instituto de Biomedicina de Sevilla IBIS, Hospital Universitario Virgen Macarena/CSIC/Departamento de Microbiología, Universidad de Sevilla, Seville, Spain
| | - F Docobo-Pérez
- Departamento de Microbiología, Facultad de Medicina, Universidad de Sevilla, Sevilla, Spain.,Red Española de Investigación en Patología Infecciosa (REIPI), Instituto de Salud Carlos III, Madrid, Spain.,Instituto de Biomedicina de Sevilla IBIS, Hospital Universitario Virgen Macarena/CSIC/Departamento de Microbiología, Universidad de Sevilla, Seville, Spain
| | - A Pascual
- Unidad Clínica de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospital Universitario Virgen Macarena, Seville, Spain.,Departamento de Microbiología, Facultad de Medicina, Universidad de Sevilla, Sevilla, Spain.,Red Española de Investigación en Patología Infecciosa (REIPI), Instituto de Salud Carlos III, Madrid, Spain.,Instituto de Biomedicina de Sevilla IBIS, Hospital Universitario Virgen Macarena/CSIC/Departamento de Microbiología, Universidad de Sevilla, Seville, Spain
| | - J M Rodríguez-Martínez
- Departamento de Microbiología, Facultad de Medicina, Universidad de Sevilla, Sevilla, Spain.,Red Española de Investigación en Patología Infecciosa (REIPI), Instituto de Salud Carlos III, Madrid, Spain.,Instituto de Biomedicina de Sevilla IBIS, Hospital Universitario Virgen Macarena/CSIC/Departamento de Microbiología, Universidad de Sevilla, Seville, Spain
| |
Collapse
|
12
|
Chlebicka K, Bonar E, Suder P, Ostyn E, Felden B, Wladyka B, Pinel-Marie ML. Impacts of the Type I Toxin-Antitoxin System, SprG1/SprF1, on Staphylococcus aureus Gene Expression. Genes (Basel) 2021; 12:genes12050770. [PMID: 34070083 PMCID: PMC8158120 DOI: 10.3390/genes12050770] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 05/14/2021] [Accepted: 05/16/2021] [Indexed: 11/16/2022] Open
Abstract
Type I toxin-antitoxin (TA) systems are widespread genetic modules in bacterial genomes. They express toxic peptides whose overexpression leads to growth arrest or cell death, whereas antitoxins regulate the expression of toxins, acting as labile antisense RNAs. The Staphylococcus aureus (S. aureus) genome contains and expresses several functional type I TA systems, but their biological functions remain unclear. Here, we addressed and challenged experimentally, by proteomics, if the type I TA system, the SprG1/SprF1 pair, influences the overall gene expression in S. aureus. Deleted and complemented S. aureus strains were analyzed for their proteomes, both intracellular and extracellular, during growth. Comparison of intracellular proteomes among the strains points to the SprF1 antitoxin as moderately downregulating protein expression. In the strain naturally expressing the SprG1 toxin, cytoplasmic proteins are excreted into the medium, but this is not due to unspecific cell leakages. Such a toxin-driven release of the cytoplasmic proteins may modulate the host inflammatory response that, in turn, could amplify the S. aureus infection spread.
Collapse
Affiliation(s)
- Kinga Chlebicka
- Department of Analytical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Krakow, Poland; (K.C.); (E.B.)
| | - Emilia Bonar
- Department of Analytical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Krakow, Poland; (K.C.); (E.B.)
| | - Piotr Suder
- Department of Analytical Chemistry and Biochemistry, Faculty of Materials Science and Ceramics, AGH University of Science and Technology, 31-007 Krakow, Poland;
| | - Emeline Ostyn
- Inserm, BRM [Bacterial Regulatory RNAs and Medicine]—UMR_S 1230, 35000 Rennes, France;
| | - Brice Felden
- Inserm, BRM [Bacterial Regulatory RNAs and Medicine]—UMR_S 1230, 35000 Rennes, France;
| | - Benedykt Wladyka
- Department of Analytical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Krakow, Poland; (K.C.); (E.B.)
- Correspondence: (B.W.); (M.-L.P.-M.); Tel.: +48-126646511 (B.W.); +33-223234850 (M.-L.P.-M.)
| | - Marie-Laure Pinel-Marie
- Inserm, BRM [Bacterial Regulatory RNAs and Medicine]—UMR_S 1230, 35000 Rennes, France;
- Correspondence: (B.W.); (M.-L.P.-M.); Tel.: +48-126646511 (B.W.); +33-223234850 (M.-L.P.-M.)
| |
Collapse
|
13
|
Phosphate-dependent aggregation of [KL] n peptides affects their membranolytic activity. Sci Rep 2020; 10:12300. [PMID: 32704013 PMCID: PMC7378186 DOI: 10.1038/s41598-020-69162-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 06/25/2020] [Indexed: 11/25/2022] Open
Abstract
In this study, we investigate how the length of amphiphilic β-sheet forming peptides affects their interaction with membranes. Four polycationic model peptides with lengths from 6 to 18 amino acids were constructed from simple Lys-Leu repeats, giving [KL]n=3,5,7,9. We found that (1) they exhibit a pronounced antimicrobial activity with an intriguing length dependent maximum for [KL]5 with 10 amino acids; (2) their hemolytic effect, on the other hand, increases steadily with peptide length. CD analysis (3) and TEM (4) show that all peptides-except for the short [KL]3-aggregate into amyloid-like fibrils in the presence of phosphate ions, which in turn has a critical effect on the results in (1) and (2). In fact, (5) vesicle leakage reveals an intrinsic membrane-perturbing activity (at constant peptide mass) of [KL]5 > [KL]9 > [KL]7 in phosphate buffer, which changes to [KL]5 ≈ [KL]7 ≈ [KL]9 in PIPES. A specific interaction with phosphate ions thus explains the subtle balance between two counteracting effects: phosphate-induced unproductive pre-aggregation in solution versus monomeric membrane binding and vigorous lipid perturbation due to self-assembly of the bound peptides within the bilayer. This knowledge can now be used to control and optimize the peptides in further applications.
Collapse
|
14
|
Garai P, Blanc‐Potard A. Uncovering small membrane proteins in pathogenic bacteria: Regulatory functions and therapeutic potential. Mol Microbiol 2020; 114:710-720. [DOI: 10.1111/mmi.14564] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 06/19/2020] [Accepted: 06/20/2020] [Indexed: 01/01/2023]
Affiliation(s)
- Preeti Garai
- Laboratory of Pathogen‐Host Interactions Université de MontpellierCNRS‐UMR5235 Montpellier France
| | - Anne Blanc‐Potard
- Laboratory of Pathogen‐Host Interactions Université de MontpellierCNRS‐UMR5235 Montpellier France
| |
Collapse
|
15
|
Yu Z, Xu Y, Zhu L, Zhang L, Liu L, Zhang D, Li D, Wu C, Huang J, Yang G, Yan K, Zhang S, Zheng C. The Brassicaceae-specific secreted peptides, STMPs, function in plant growth and pathogen defense. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2020; 62:403-420. [PMID: 31001913 DOI: 10.1111/jipb.12817] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 04/11/2019] [Indexed: 06/09/2023]
Abstract
Low molecular weight secreted peptides have recently been shown to affect multiple aspects of plant growth, development, and defense responses. Here, we performed stepwise BLAST filtering to identify unannotated peptides from the Arabidopsis thaliana protein database and uncovered a novel secreted peptide family, secreted transmembrane peptides (STMPs). These low molecular weight peptides, which consist of an N-terminal signal peptide and a transmembrane domain, were primarily localized to extracellular compartments but were also detected in the endomembrane system of the secretory pathway, including the endoplasmic reticulum and Golgi. Comprehensive bioinformatics analysis identified 10 STMP family members that are specific to the Brassicaceae family. Brassicaceae plants showed dramatically inhibited root growth upon exposure to chemically synthesized STMP1 and STMP2. Arabidopsis overexpressing STMP1, 2, 4, 6, or 10 exhibited severely arrested growth, suggesting that STMPs are involved in regulating plant growth and development. In addition, in vitro bioassays demonstrated that STMP1, STMP2, and STMP10 have antibacterial effects against Pseudomonas syringae pv. tomato DC3000, Ralstonia solanacearum, Bacillus subtilis, and Agrobacterium tumefaciens, demonstrating that STMPs are antimicrobial peptides. These findings suggest that STMP family members play important roles in various developmental events and pathogen defense responses in Brassicaceae plants.
Collapse
Affiliation(s)
- Zipeng Yu
- State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, 271018, China
| | - Yang Xu
- State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, 271018, China
- Shandong Peanut Research Institute, Shandong Academy of Agricultural Sciences, Qingdao, 266100, China
| | - Lifei Zhu
- State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, 271018, China
| | - Lei Zhang
- State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, 271018, China
| | - Lin Liu
- State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, 271018, China
| | - Di Zhang
- State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, 271018, China
| | - Dandan Li
- State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, 271018, China
| | - Changai Wu
- State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, 271018, China
| | - Jinguang Huang
- State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, 271018, China
| | - Guodong Yang
- State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, 271018, China
| | - Kang Yan
- State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, 271018, China
| | - Shizhong Zhang
- State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, 271018, China
| | - Chengchao Zheng
- State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, 271018, China
| |
Collapse
|
16
|
Structural insights into the AapA1 toxin of Helicobacter pylori. Biochim Biophys Acta Gen Subj 2019; 1864:129423. [PMID: 31476357 DOI: 10.1016/j.bbagen.2019.129423] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 08/12/2019] [Accepted: 08/28/2019] [Indexed: 02/06/2023]
Abstract
BACKGROUND We previously reported the identification of the aapA1/IsoA1 locus as part of a new family of toxin-antitoxin (TA) systems in the human pathogen Helicobacter pylori. AapA1 belongs to type I TA bacterial toxins, and both its mechanism of action towards the membrane and toxicity features are still unclear. METHODS The biochemical characterization of the AapA1 toxic peptide was carried out using plasmid-borne expression and mutational approaches to follow its toxicity and localization. Biophysical properties of the AapA1 interaction with lipid membranes were studied by solution and solid-state NMR spectroscopy, plasmon waveguide resonance (PWR) and molecular modeling. RESULTS We show that despite a low hydrophobic index, this toxin has a nanomolar affinity to the prokaryotic membrane. NMR spectroscopy reveals that the AapA1 toxin is structurally organized into three distinct domains: a positively charged disordered N-terminal domain (D), a single α-helix (H), and a basic C-terminal domain (R). The R domain interacts and destabilizes the membrane, while the H domain adopts a transmembrane conformation. These results were confirmed by alanine scanning of the minimal sequence required for toxicity. CONCLUSION Our results have shown that specific amino acid residues along the H domain, as well as the R domain, are essential for the toxicity of the AapA1 toxin. GENERAL SIGNIFICANCE Untangling and understanding the mechanism of action of small membrane-targeting toxins are difficult, but nevertheless contributes to a promising search and development of new antimicrobial drugs.
Collapse
|
17
|
Large-Scale Analyses of Human Microbiomes Reveal Thousands of Small, Novel Genes. Cell 2019; 178:1245-1259.e14. [PMID: 31402174 DOI: 10.1016/j.cell.2019.07.016] [Citation(s) in RCA: 135] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 05/06/2019] [Accepted: 07/11/2019] [Indexed: 12/12/2022]
Abstract
Small proteins are traditionally overlooked due to computational and experimental difficulties in detecting them. To systematically identify small proteins, we carried out a comparative genomics study on 1,773 human-associated metagenomes from four different body sites. We describe >4,000 conserved protein families, the majority of which are novel; ∼30% of these protein families are predicted to be secreted or transmembrane. Over 90% of the small protein families have no known domain and almost half are not represented in reference genomes. We identify putative housekeeping, mammalian-specific, defense-related, and protein families that are likely to be horizontally transferred. We provide evidence of transcription and translation for a subset of these families. Our study suggests that small proteins are highly abundant and those of the human microbiome, in particular, may perform diverse functions that have not been previously reported.
Collapse
|
18
|
Abstract
The origin of novel genes and beneficial functions is of fundamental interest in evolutionary biology. New genes can originate from different mechanisms, including horizontal gene transfer, duplication-divergence, and de novo from noncoding DNA sequences. Comparative genomics has generated strong evidence for de novo emergence of genes in various organisms, but experimental demonstration of this process has been limited to localized randomization in preexisting structural scaffolds. This bypasses the basic requirement of de novo gene emergence, i.e., lack of an ancestral gene. We constructed highly diverse plasmid libraries encoding randomly generated open reading frames and expressed them in Escherichia coli to identify short peptides that could confer a beneficial and selectable phenotype in vivo (in a living cell). Selections on antibiotic-containing agar plates resulted in the identification of three peptides that increased aminoglycoside resistance up to 48-fold. Combining genetic and functional analyses, we show that the peptides are highly hydrophobic, and by inserting into the membrane, they reduce membrane potential, decrease aminoglycoside uptake, and thereby confer high-level resistance. This study demonstrates that randomized DNA sequences can encode peptides that confer selective benefits and illustrates how expression of random sequences could spark the origination of new genes. In addition, our results also show that this question can be addressed experimentally by expression of highly diverse sequence libraries and subsequent selection for specific functions, such as resistance to toxic compounds, the ability to rescue auxotrophic/temperature-sensitive mutants, and growth on normally nonused carbon sources, allowing the exploration of many different phenotypes.IMPORTANCE De novo gene origination from nonfunctional DNA sequences was long assumed to be implausible. However, recent studies have shown that large fractions of genomic noncoding DNA are transcribed and translated, potentially generating new genes. Experimental validation of this process so far has been limited to comparative genomics, in vitro selections, or partial randomizations. Here, we describe selection of novel peptides in vivo using fully random synthetic expression libraries. The peptides confer aminoglycoside resistance by inserting into the bacterial membrane and thereby partly reducing membrane potential and decreasing drug uptake. Our results show that beneficial peptides can be selected from random sequence pools in vivo and support the idea that expression of noncoding sequences could spark the origination of new genes.
Collapse
|
19
|
Barbosa LCB, Dos Santos Carrijo R, da Conceição MB, Campanella JEM, Júnior EC, Secches TO, Bertolini MC, Marchetto R. Characterization of an OrtT-like toxin of Salmonella enterica serovar Houten. Braz J Microbiol 2019; 50:839-848. [PMID: 31055774 DOI: 10.1007/s42770-019-00085-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 04/25/2019] [Indexed: 01/09/2023] Open
Abstract
The Escherichia coli GhoT/GhoS system is a type V toxin-antitoxin system in which the antitoxin GhoS cleaves the GhoT mRNA, controlling its translation. GhoT is a small hydrophobic protein that damages bacterial membranes. OrtT is a GhoT-like toxin, but it apparently lacks a corresponding antitoxin and serves a different physiologic role. Using a profile hidden Markov model approach, a Salmonella enterica serovar Houten genome was screened to obtain homologs of GhoT/OrtT. We only found one protein (referred to here as OrtT-Sal) that shared more sequence identity with OrtT than GhoT. The chromosomal region around the coding sequence of OrtT-Sal suggests that it is an orphan toxin and can be under RpoH activation. To study OrtT-Sal, we chemically synthesized and expressed in E. coli the whole toxin and its N- and C-terminal regions (OrtT-Sal1-29 and OrtT-Sal29-57, respectively). Our findings have shown that the overproduction of the polypeptides resulted in severe growth inhibition and cell lysis. Using circular dichroism, we found that OrtT-Sal, OrtT-Sal1-29, and OrtT-Sal29-57 form an alpha-helical structure in the presence of SDS micelles or TFE. Finally, using carboxyfluorescein-loaded lipid vesicles, we determined that the polypeptides damage lipid membrane directly.
Collapse
Affiliation(s)
- Luiz Carlos Bertucci Barbosa
- Institute of Natural Resources, Federal University of Itajubá, BPS, 1303, Bairro Pinheirinho, Itajubá, MG, 37500-903, Brazil.
| | | | | | | | | | - Thais Oliveira Secches
- Institute of Natural Resources, Federal University of Itajubá, BPS, 1303, Bairro Pinheirinho, Itajubá, MG, 37500-903, Brazil
| | | | - Reinaldo Marchetto
- Institute of Chemistry, São Paulo State University, Araraquara, SP, Brazil
| |
Collapse
|
20
|
Schneider V, Wadhwani P, Reichert J, Bürck J, Elstner M, Ulrich AS, Kubař T. Tetrameric Charge-Zipper Assembly of the TisB Peptide in Membranes—Computer Simulation and Experiment. J Phys Chem B 2019; 123:1770-1779. [DOI: 10.1021/acs.jpcb.8b12087] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
| | - Parvesh Wadhwani
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology, P. O. Box 3640, 76021 Karlsruhe, Germany
| | - Johannes Reichert
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology, P. O. Box 3640, 76021 Karlsruhe, Germany
| | - Jochen Bürck
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology, P. O. Box 3640, 76021 Karlsruhe, Germany
| | - Marcus Elstner
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology, P. O. Box 3640, 76021 Karlsruhe, Germany
| | - Anne S. Ulrich
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology, P. O. Box 3640, 76021 Karlsruhe, Germany
| | | |
Collapse
|
21
|
Reißer S, Prock S, Heinzmann H, Ulrich AS. Protein ORIGAMI: A program for the creation of 3D paper models of folded peptides. BIOCHEMISTRY AND MOLECULAR BIOLOGY EDUCATION : A BIMONTHLY PUBLICATION OF THE INTERNATIONAL UNION OF BIOCHEMISTRY AND MOLECULAR BIOLOGY 2018; 46:403-409. [PMID: 29984554 DOI: 10.1002/bmb.21132] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 04/20/2018] [Accepted: 05/03/2018] [Indexed: 06/08/2023]
Abstract
Protein ORIGAMI (http://ibg.kit.edu/protein_origami) is a browser-based web application that allows the user to create straightforward 3D paper models of folded peptides for research, teaching and presentations. An amino acid sequence can be turned into α-helices, β-strands and random coils that can be printed out and folded into properly scaled models, with a color code denoting the biophysical characteristics of each amino acid residue (hydrophobicity, charge, etc.). These models provide an intuitive visual and tactile understanding of peptide interactions with other partners, such as helix-helix assembly, oligomerization, membrane binding, or pore formation. Helices can also be displayed as a helical wheel or helical mesh in 2D graphics, to be used in publications or presentations. The highly versatile programme Protein ORIGAMI is also suited to create less conventional helices with arbitrary pitch (e.g., 310 -helix, π-helix, or left-handed helices). Noncanonical amino acids, labels and different terminal modifications can be defined and displayed at will, and different protonation states can be shown. In addition to the web application, the program source code can be downloaded and installed locally on a PC. The printed paper models can be readily used for daily research and discussions, just as for educational purposes and teaching. © 2018 by The International Union of Biochemistry and Molecular Biology, 46:403-409, 2018.
Collapse
Affiliation(s)
- Sabine Reißer
- Institute of Organic Chemistry (IOC), Karlsruhe Institute of Technology (KIT), Karlsruhe, 76133, Germany
- Scuola Internazionale Superiore di Studi Avanzati (SISSA), Trieste, 34136, Italy
| | - Sebastian Prock
- Institute of Organic Chemistry (IOC), Karlsruhe Institute of Technology (KIT), Karlsruhe, 76133, Germany
| | - Hartmut Heinzmann
- Institute of Biological Interfaces (IBG-2), KIT, Karlsruhe, 76012, Germany
| | - Anne S Ulrich
- Institute of Organic Chemistry (IOC), Karlsruhe Institute of Technology (KIT), Karlsruhe, 76133, Germany
- Institute of Biological Interfaces (IBG-2), KIT, Karlsruhe, 76012, Germany
| |
Collapse
|
22
|
Strandberg E, Grau-Campistany A, Wadhwani P, Bürck J, Rabanal F, Ulrich AS. Helix Fraying and Lipid-Dependent Structure of a Short Amphipathic Membrane-Bound Peptide Revealed by Solid-State NMR. J Phys Chem B 2018; 122:6236-6250. [DOI: 10.1021/acs.jpcb.8b02661] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Erik Strandberg
- Karlsruhe Institute of Technology (KIT), Institute of Biological Interfaces (IBG-2), P.O. Box 3640, 76021 Karlsruhe, Germany
| | - Ariadna Grau-Campistany
- Secció de Química Orgànica, Departament de Química Inorgànica i Orgànica, Facultat de Química, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Parvesh Wadhwani
- Karlsruhe Institute of Technology (KIT), Institute of Biological Interfaces (IBG-2), P.O. Box 3640, 76021 Karlsruhe, Germany
| | - Jochen Bürck
- Karlsruhe Institute of Technology (KIT), Institute of Biological Interfaces (IBG-2), P.O. Box 3640, 76021 Karlsruhe, Germany
| | - Francesc Rabanal
- Secció de Química Orgànica, Departament de Química Inorgànica i Orgànica, Facultat de Química, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Anne S. Ulrich
- Karlsruhe Institute of Technology (KIT), Institute of Biological Interfaces (IBG-2), P.O. Box 3640, 76021 Karlsruhe, Germany
- KIT, Institute of Organic Chemistry, Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany
| |
Collapse
|
23
|
GhoT of the GhoT/GhoS toxin/antitoxin system damages lipid membranes by forming transient pores. Biochem Biophys Res Commun 2018; 497:467-472. [PMID: 29470981 DOI: 10.1016/j.bbrc.2018.01.067] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 01/10/2018] [Indexed: 11/20/2022]
Abstract
GhoT is a bacterial toxin of the type V toxin/antitoxin system that allows Escherichia coli to reduce its metabolism in response to oxidative and bile stress. GhoT functions by increasing membrane permeability and reducing both ATP levels and the proton motive force. However, how GhoT damages the inner membrane has not been elucidated. Here we investigated how GhoT damages membranes by studying its interaction with lipid bilayers and determined that GhoT does not cause macroscopic disruption of the lipid bilayer to increase membrane permeability to the dye carboxyfluorescein. Using circular dichroism, we found that GhoT forms an alpha helical structure in lipid bilayers that agrees with the structure predicted by the I-TASSER protein structure prediction program. The structure generated using I-TASSER was used to conduct coarse-grained molecular dynamics simulations, which indicate that GhoT damages the cell membrane, as a multimer, by forming transient transmembrane pores.
Collapse
|
24
|
Duval M, Cossart P. Small bacterial and phagic proteins: an updated view on a rapidly moving field. Curr Opin Microbiol 2017; 39:81-88. [PMID: 29111488 DOI: 10.1016/j.mib.2017.09.010] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 09/17/2017] [Indexed: 01/21/2023]
Abstract
Small proteins, that is, polypeptides of 50 amino acids (aa) or less, are increasingly recognized as important regulators in bacteria. Secreted or not, their small size make them versatile proteins, involved in a wide range of processes. They may allow bacteria to sense and to respond to stresses, to send signals and communicate, and to modulate infections. Bacteriophages also produce small proteins to influence lysogeny/lysis decisions. In this review, we update the present view on small proteins functions, and discuss their possible applications.
Collapse
Affiliation(s)
- Mélodie Duval
- Unité des Interactions Bactéries-Cellules, Institut Pasteur, Paris F-75015, France; Institut National de la Santé et de la Recherche Médicale, U604, Paris F-75015, France; Institut National de la Recherche Agronomique, Unité Sous Contrat 2020, Paris F-75015, France.
| | - Pascale Cossart
- Unité des Interactions Bactéries-Cellules, Institut Pasteur, Paris F-75015, France; Institut National de la Santé et de la Recherche Médicale, U604, Paris F-75015, France; Institut National de la Recherche Agronomique, Unité Sous Contrat 2020, Paris F-75015, France.
| |
Collapse
|
25
|
Gagnon MC, Strandberg E, Grau-Campistany A, Wadhwani P, Reichert J, Bürck J, Rabanal F, Auger M, Paquin JF, Ulrich AS. Influence of the Length and Charge on the Activity of α-Helical Amphipathic Antimicrobial Peptides. Biochemistry 2017; 56:1680-1695. [PMID: 28282123 DOI: 10.1021/acs.biochem.6b01071] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Hydrophobic mismatch is important for pore-forming amphipathic antimicrobial peptides, as demonstrated recently [Grau-Campistany, A., et al. (2015) Sci. Rep. 5, 9388]. A series of different length peptides have been generated with the heptameric repeat sequence KIAGKIA, called KIA peptides, and it was found that only those helices sufficiently long to span the hydrophobic thickness of the membrane could induce leakage in lipid vesicles; there was also a clear length dependence of the antimicrobial and hemolytic activities. For the original KIA sequences, the cationic charge increased with peptide length. The goal of this work is to examine whether the charge also has an effect on activity; hence, we constructed two further series of peptides with a sequence similar to those of the KIA peptides, but with a constant charge of +7 for all lengths from 14 to 28 amino acids. For both of these new series, a clear length dependence similar to that of KIA peptides was observed, indicating that charge has only a minor influence. Both series also showed a distinct threshold length for peptides to be active, which correlates directly with the thickness of the membrane. Among the longer peptides, the new series showed activities only slightly lower than those of the original KIA peptides of the same length that had a higher charge. Shorter peptides, in which Gly was replaced with Lys, showed activities similar to those of KIA peptides of the same length, but peptides in which Ile was replaced with Lys lost their helicity and were less active.
Collapse
Affiliation(s)
- Marie-Claude Gagnon
- Department of Chemistry, PROTEO, CGCC, Université Laval , 1045 avenue de la Médecine, Québec, Canada G1V 0A6.,Department of Chemistry, PROTEO, CERMA, CQMF, Université Laval , 1045 avenue de la Médecine, Québec, Canada G1V 0A6
| | - Erik Strandberg
- Karlsruhe Institute of Technology (KIT) , Institute of Biological Interfaces (IBG-2), P.O. Box 3640, 76021 Karlsruhe, Germany
| | - Ariadna Grau-Campistany
- Secció de Química Orgànica, Departament de Química Inorgànica i Orgànica, Facultat de Química, Universitat de Barcelona , Barcelona, Spain
| | - Parvesh Wadhwani
- Karlsruhe Institute of Technology (KIT) , Institute of Biological Interfaces (IBG-2), P.O. Box 3640, 76021 Karlsruhe, Germany
| | - Johannes Reichert
- Karlsruhe Institute of Technology (KIT) , Institute of Biological Interfaces (IBG-2), P.O. Box 3640, 76021 Karlsruhe, Germany
| | - Jochen Bürck
- Karlsruhe Institute of Technology (KIT) , Institute of Biological Interfaces (IBG-2), P.O. Box 3640, 76021 Karlsruhe, Germany
| | - Francesc Rabanal
- Secció de Química Orgànica, Departament de Química Inorgànica i Orgànica, Facultat de Química, Universitat de Barcelona , Barcelona, Spain
| | - Michèle Auger
- Department of Chemistry, PROTEO, CERMA, CQMF, Université Laval , 1045 avenue de la Médecine, Québec, Canada G1V 0A6
| | - Jean-François Paquin
- Department of Chemistry, PROTEO, CGCC, Université Laval , 1045 avenue de la Médecine, Québec, Canada G1V 0A6
| | - Anne S Ulrich
- Karlsruhe Institute of Technology (KIT) , Institute of Biological Interfaces (IBG-2), P.O. Box 3640, 76021 Karlsruhe, Germany.,KIT , Institute of Organic Chemistry, Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany
| |
Collapse
|
26
|
Grage SL, Sani MA, Cheneval O, Henriques ST, Schalck C, Heinzmann R, Mylne JS, Mykhailiuk PK, Afonin S, Komarov IV, Separovic F, Craik DJ, Ulrich AS. Orientation and Location of the Cyclotide Kalata B1 in Lipid Bilayers Revealed by Solid-State NMR. Biophys J 2017; 112:630-642. [PMID: 28256223 PMCID: PMC5340158 DOI: 10.1016/j.bpj.2016.12.040] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 12/23/2016] [Accepted: 12/29/2016] [Indexed: 02/04/2023] Open
Abstract
Cyclotides are ultra-stable cyclic disulfide-rich peptides from plants. Their biophysical effects and medically interesting activities are related to their membrane-binding properties, with particularly high affinity for phosphatidylethanolamine lipids. In this study we were interested in understanding the molecular details of cyclotide-membrane interactions, specifically with regard to the spatial orientation of the cyclotide kalata B1 from Oldenlandia affinis when embedded in a lipid bilayer. Our experimental approach was based on the use of solid-state 19F-NMR of oriented bilayers in conjunction with the conformationally restricted amino acid L-3-(trifluoromethyl)bicyclopent-[1.1.1]-1-ylglycine as an orientation-sensitive 19F-NMR probe. Its rigid connection to the kalata B1 backbone scaffold, together with the well-defined structure of the cyclotide, allowed us to calculate the protein alignment in the membrane directly from the orientation-sensitive 19F-NMR signal. The hydrophobic and polar residues on the surface of kalata B1 form well-separated patches, endowing this cyclotide with a pronounced amphipathicity. The peptide orientation, as determined by NMR, showed that this amphipathic structure matches the polar/apolar interface of the lipid bilayer very well. A location in the amphiphilic headgroup region of the bilayer was supported by 15N-NMR of uniformly labeled protein, and confirmed using solid-state 31P- and 2H-NMR. 31P-NMR relaxation data indicated a change in lipid headgroup dynamics induced by kalata B1. Changes in the 2H-NMR order parameter profile of the acyl chains suggest membrane thinning, as typically observed for amphiphilic peptides embedded near the polar/apolar bilayer interface. Furthermore, from the 19F-NMR analysis two important charged residues, E7 and R28, were found to be positioned equatorially. The observed location thus would be favorable for the postulated binding of E7 to phosphatidylethanolamine lipid headgroups. Furthermore, it may be speculated that this pair of side chains could promote oligomerization of kalata B1 through electrostatic intermolecular contacts via their complementary charges.
Collapse
Affiliation(s)
- Stephan L Grage
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Marc-Antoine Sani
- School of Chemistry, Bio21 Institute, The University of Melbourne, Melbourne, Victoria, Australia
| | - Olivier Cheneval
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - Sónia Troeira Henriques
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - Constantin Schalck
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Ralf Heinzmann
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Joshua S Mylne
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - Pavel K Mykhailiuk
- Chemistry Department, Taras Shevchenko National University of Kyiv, Kyiv, Ukraine; Enamine Ltd., Kyiv, Ukraine
| | - Sergii Afonin
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Igor V Komarov
- Institute of High Technologies, Taras Shevchenko National University of Kyiv, Kyiv, Ukraine
| | - Frances Separovic
- School of Chemistry, Bio21 Institute, The University of Melbourne, Melbourne, Victoria, Australia
| | - David J Craik
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - Anne S Ulrich
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology, Karlsruhe, Germany; Institute of Organic Chemistry, Karlsruhe Institute of Technology, Karlsruhe, Germany.
| |
Collapse
|
27
|
Van den Bergh B, Fauvart M, Michiels J. Formation, physiology, ecology, evolution and clinical importance of bacterial persisters. FEMS Microbiol Rev 2017; 41:219-251. [DOI: 10.1093/femsre/fux001] [Citation(s) in RCA: 217] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 01/12/2017] [Indexed: 12/19/2022] Open
|
28
|
Savoie JD, Otis F, Bürck J, Ulrich AS, Voyer N. Crown ether helical peptides are preferentially inserted in lipid bilayers as a transmembrane ion channels. Biopolymers 2016; 104:427-33. [PMID: 25753314 DOI: 10.1002/bip.22633] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Revised: 02/18/2015] [Accepted: 02/23/2015] [Indexed: 11/08/2022]
Abstract
Oriented circular dichroism was used to study the alignment crown ether-modified peptides. The influence of different N- and C-functionalities was assessed using at variable peptide:lipid ratios from 1:20 to 1:200. Neither the functionalities nor the concentration had any major effect on the orientation. The alignment of the 21-mer peptides was also examined with lipid membranes of different bilayer thickness. The use of synchrotron radiation as light source allowed the study of peptide:lipid molar ratios from 1:20 to 1:1000. For all conditions studied, the peptides were found to be predominantly incorporated as a transmembrane helix into the membrane, especially at low peptide concentration, but started to aggregate on the membrane surface at higher peptide:lipid ratios. The structural information on the preferred trans-bilayer alignment of the crown ether functional groups explains their ion conductivity and is useful for the further development of membrane-active nanochemotherapeutics.
Collapse
Affiliation(s)
- Jean-Daniel Savoie
- Faculté des Sciences et de Génie, Département de chimie and PROTEO, Université Laval, Québec, QC, G1V 0A6, Canada.,Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology (KIT), POB 3640, 76021, Karlsruhe, Germany
| | - François Otis
- Faculté des Sciences et de Génie, Département de chimie and PROTEO, Université Laval, Québec, QC, G1V 0A6, Canada
| | - Jochen Bürck
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology (KIT), POB 3640, 76021, Karlsruhe, Germany
| | - Anne S Ulrich
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology (KIT), POB 3640, 76021, Karlsruhe, Germany
| | - Normand Voyer
- Faculté des Sciences et de Génie, Département de chimie and PROTEO, Université Laval, Québec, QC, G1V 0A6, Canada
| |
Collapse
|
29
|
Grage SL, Afonin S, Kara S, Buth G, Ulrich AS. Membrane Thinning and Thickening Induced by Membrane-Active Amphipathic Peptides. Front Cell Dev Biol 2016; 4:65. [PMID: 27595096 PMCID: PMC4999517 DOI: 10.3389/fcell.2016.00065] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 06/09/2016] [Indexed: 11/13/2022] Open
Abstract
Membrane thinning has been discussed as a fundamental mechanism by which antimicrobial peptides can perturb cellular membranes. To understand which factors play a role in this process, we compared several amphipathic peptides with different structures, sizes and functions in their influence on the lipid bilayer thickness. PGLa and magainin 2 from X. laevis were studied as typical representatives of antimicrobial cationic amphipathic α-helices. A 1:1 mixture of these peptides, which is known to possess synergistically enhanced activity, allowed us to evaluate whether and how this synergistic interaction correlates with changes in membrane thickness. Other systems investigated here include the α-helical stress-response peptide TisB from E. coli (which forms membrane-spanning dimers), as well as gramicidin S from A. migulanus (a natural antibiotic), and BP100 (designer-made antimicrobial and cell penetrating peptide). The latter two are very short, with a circular β-pleated and a compact α-helical structure, respectively. Solid-state (2)H-NMR and grazing incidence small angle X-ray scattering (GISAXS) on oriented phospholipid bilayers were used as complementary techniques to access the hydrophobic thickness as well as the bilayer-bilayer repeat distance including the water layer in between. This way, we found that magainin 2, gramicidin S, and BP100 induced membrane thinning, as expected for amphiphilic peptides residing in the polar/apolar interface of the bilayer. PGLa, on the other hand, decreased the hydrophobic thickness only at very high peptide:lipid ratios, and did not change the bilayer-bilayer repeat distance. TisB even caused an increase in the hydrophobic thickness and repeat distance. When reconstituted as a mixture, PGLa and magainin 2 showed a moderate thinning effect which was less than that of magainin 2 alone, hence their synergistically enhanced activity does not seem to correlate with a modulation of membrane thickness. Overall, the absence of a typical thinning response in the case of PGLa, and the increase in the repeat distance and membrane thickening observed for TisB, demonstrate that the concept of peptide-induced membrane thinning cannot be generalized. Instead, these results suggest that different factors contribute to the resulting changes in membrane thickness, such as the peptide orientation in the bilayer, and/or bilayer adaptation to hydrophobic mismatch.
Collapse
Affiliation(s)
- Stephan L Grage
- Karlsruhe Institute of Technology, Institute of Biological Interfaces Karlsruhe, Germany
| | - Sergii Afonin
- Karlsruhe Institute of Technology, Institute of Biological Interfaces Karlsruhe, Germany
| | - Sezgin Kara
- Karlsruhe Institute of Technology, Institute of Organic Chemistry Karlsruhe, Germany
| | - Gernot Buth
- Karlsruhe Institute of Technology, Institute for Accelerator Physics and Technology Karlsruhe, Germany
| | - Anne S Ulrich
- Karlsruhe Institute of Technology, Institute of Biological InterfacesKarlsruhe, Germany; Karlsruhe Institute of Technology, Institute of Organic ChemistryKarlsruhe, Germany
| |
Collapse
|
30
|
Windisch D, Ziegler C, Grage SL, Bürck J, Zeitler M, Gor'kov PL, Ulrich AS. Hydrophobic Mismatch Drives the Interaction of E5 with the Transmembrane Segment of PDGF Receptor. Biophys J 2016; 109:737-49. [PMID: 26287626 PMCID: PMC4547410 DOI: 10.1016/j.bpj.2015.07.022] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 07/13/2015] [Accepted: 07/14/2015] [Indexed: 02/05/2023] Open
Abstract
The oncogenic E5 protein from bovine papillomavirus is a short (44 amino acids long) integral membrane protein that forms homodimers. It activates platelet-derived growth factor receptor (PDGFR) β in a ligand-independent manner by transmembrane helix-helix interactions. The nature of this recognition event remains elusive, as numerous mutations are tolerated in the E5 transmembrane segment, with the exception of one hydrogen-bonding residue. Here, we examined the conformation, stability, and alignment of the E5 protein in fluid lipid membranes of substantially varying bilayer thickness, in both the absence and presence of the PDGFR transmembrane segment. Quantitative synchrotron radiation circular dichroism analysis revealed a very long transmembrane helix for E5 of ∼26 amino acids. Oriented circular dichroism and solid-state 15N-NMR showed that the alignment and stability of this unusually long segment depend critically on the membrane thickness. When reconstituted alone in exceptionally thick DNPC lipid bilayers, the E5 helix was found to be inserted almost upright. In moderately thick bilayers (DErPC and DEiPC), it started to tilt and became slightly deformed, and finally it became aggregated in conventional DOPC, POPC, and DMPC membranes due to hydrophobic mismatch. On the other hand, when E5 was co-reconstituted with the transmembrane segment of PDGFR, it was able to tolerate even the most pronounced mismatch and was stabilized by binding to the receptor, which has the same hydrophobic length. As E5 is known to activate PDGFR within the thin membranes of the Golgi compartment, we suggest that the intrinsic hydrophobic mismatch of these two interaction partners drives them together. They seem to recognize each other by forming a closely packed bundle of mutually aligned transmembrane helices, which is further stabilized by a specific pair of hydrogen-bonding residues.
Collapse
Affiliation(s)
- Dirk Windisch
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Colin Ziegler
- Institute of Organic Chemistry, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Stephan L Grage
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Jochen Bürck
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Marcel Zeitler
- Institute of Organic Chemistry, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Peter L Gor'kov
- National High Magnetic Field Laboratory, Tallahassee, Florida
| | - Anne S Ulrich
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology, Karlsruhe, Germany; Institute of Organic Chemistry, Karlsruhe Institute of Technology, Karlsruhe, Germany.
| |
Collapse
|
31
|
Conlon BP, Rowe SE, Gandt AB, Nuxoll AS, Donegan NP, Zalis EA, Clair G, Adkins JN, Cheung AL, Lewis K. Persister formation in Staphylococcus aureus is associated with ATP depletion. Nat Microbiol 2016; 1:16051. [PMID: 27398229 PMCID: PMC4932909 DOI: 10.1038/nmicrobiol.2016.51] [Citation(s) in RCA: 416] [Impact Index Per Article: 52.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 03/15/2016] [Indexed: 01/06/2023]
Abstract
Persisters are dormant phenotypic variants of bacterial cells that are tolerant to killing by antibiotics1. Persisters are associated with chronic infections and antibiotic treatment failure1-3. In Escherichia coli, toxin/antitoxin (TA) modules have been linked to persister formation4-6. The mechanism of persister formation in Gram-positive bacteria is unknown. Staphylococcus aureus is a major human pathogen, responsible for a variety of chronic and relapsing infections such as osteomyelitis, endocarditis and infections of implanted devices. Deleting TA modules in S. aureus did not affect the level of persisters. Here we show that S. aureus persisters are produced due to a stochastic entrance into stationary phase accompanied by a drop in intracellular ATP. Cells expressing stationary state markers are present throughout the growth phase, increasing in frequency with cell density. Cell sorting revealed that expression of stationary markers is associated with a 100-1000 fold increase in the likelihood of survival to antibiotic challenge. The ATP level of the cell is predictive of bactericidal antibiotic efficacy and explains bacterial tolerance to antibiotics.
Collapse
Affiliation(s)
- Brian P. Conlon
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Massachusetts 02115
| | - Sarah E. Rowe
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Massachusetts 02115
- Synlogic, Cambridge, Massachusetts 02139
| | - Autumn Brown Gandt
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Massachusetts 02115
| | - Austin S. Nuxoll
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Massachusetts 02115
| | - Niles P. Donegan
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, 03755
| | - Eliza A. Zalis
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Massachusetts 02115
| | - Geremy Clair
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352
| | - Joshua N. Adkins
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352
| | - Ambrose L. Cheung
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, 03755
| | - Kim Lewis
- Antimicrobial Discovery Center, Department of Biology, Northeastern University, Massachusetts 02115
| |
Collapse
|
32
|
Zerweck J, Strandberg E, Bürck J, Reichert J, Wadhwani P, Kukharenko O, Ulrich AS. Homo- and heteromeric interaction strengths of the synergistic antimicrobial peptides PGLa and magainin 2 in membranes. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2016; 45:535-47. [PMID: 27052218 DOI: 10.1007/s00249-016-1120-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 02/01/2016] [Accepted: 02/16/2016] [Indexed: 12/11/2022]
Abstract
PGLa and magainin 2 (MAG2) are amphiphilic α-helical frog peptides with synergistic antimicrobial activity. In vesicle leakage assays we observed the strongest synergy for equimolar mixtures of PGLa and MAG2. This result was consistent with solid-state (15)N-NMR data on the helix alignment in model membranes. The Hill coefficients determined from the vesicle leakage data showed that the heterodimeric (PGLa-MAG2) interactions were stronger than the homodimeric (PGLa-PGLa and MAG2-MAG2) interactions. This result was also reflected in the free energy of dimerization determined from oriented circular dichroism and quantitative solid-state (19)F-NMR analysis.
Collapse
Affiliation(s)
- Jonathan Zerweck
- Karlsruhe Institute of Technology (KIT), Institute of Organic Chemistry, Fritz-Haber-Weg 6, 76131, Karlsruhe, Germany
| | - Erik Strandberg
- KIT, Institute of Biological Interfaces (IBG-2), POB 3640, 76021, Karlsruhe, Germany
| | - Jochen Bürck
- KIT, Institute of Biological Interfaces (IBG-2), POB 3640, 76021, Karlsruhe, Germany
| | - Johannes Reichert
- KIT, Institute of Biological Interfaces (IBG-2), POB 3640, 76021, Karlsruhe, Germany
| | - Parvesh Wadhwani
- KIT, Institute of Biological Interfaces (IBG-2), POB 3640, 76021, Karlsruhe, Germany
| | - Olga Kukharenko
- Karlsruhe Institute of Technology (KIT), Institute of Organic Chemistry, Fritz-Haber-Weg 6, 76131, Karlsruhe, Germany
| | - Anne S Ulrich
- Karlsruhe Institute of Technology (KIT), Institute of Organic Chemistry, Fritz-Haber-Weg 6, 76131, Karlsruhe, Germany. .,KIT, Institute of Biological Interfaces (IBG-2), POB 3640, 76021, Karlsruhe, Germany.
| |
Collapse
|
33
|
Li ZL, Ding HM, Ma YQ. Interaction of peptides with cell membranes: insights from molecular modeling. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:083001. [PMID: 26828575 DOI: 10.1088/0953-8984/28/8/083001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The investigation of the interaction of peptides with cell membranes is the focus of active research. It can enhance the understanding of basic membrane functions such as membrane transport, fusion, and signaling processes, and it may shed light on potential applications of peptides in biomedicine. In this review, we will present current advances in computational studies on the interaction of different types of peptides with the cell membrane. Depending on the properties of the peptide, membrane, and external environment, the peptide-membrane interaction shows a variety of different forms. Here, on the basis of recent computational progress, we will discuss how different peptides could initiate membrane pores, translocate across the membrane, induce membrane endocytosis, produce membrane curvature, form fibrils on the membrane surface, as well as interact with functional membrane proteins. Finally, we will present a conclusion summarizing recent progress and providing some specific insights into future developments in this field.
Collapse
Affiliation(s)
- Zhen-lu Li
- National Laboratory of Solid State Microstructures and Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
| | | | | |
Collapse
|
34
|
Bürck J, Wadhwani P, Fanghänel S, Ulrich AS. Oriented Circular Dichroism: A Method to Characterize Membrane-Active Peptides in Oriented Lipid Bilayers. Acc Chem Res 2016; 49:184-92. [PMID: 26756718 DOI: 10.1021/acs.accounts.5b00346] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The structures of membrane-bound polypeptides are intimately related to their functions and may change dramatically with the lipid environment. Circular dichroism (CD) is a rapid analytical method that requires relatively low amounts of material and no labeling. Conventional CD is routinely used to monitor the secondary structure of peptides and proteins in solution, for example, in the presence of ligands and other binding partners. In the case of membrane-active peptides and transmembrane proteins, these measurements can be applied to, and remain limited to, samples containing detergent micelles or small sonicated lipid vesicles. Such traditional CD analysis reveals only secondary structures. With the help of an oriented circular dichroism (OCD) setup, however, based on the preparation of macroscopically oriented lipid bilayers, it is possible to address the membrane alignment of a peptide in addition to its conformation. This approach has been mostly used for α-helical peptides so far, but other structural elements are conceivable as well. OCD analysis relies on Moffitt's theory, which predicts that the electronic transition dipole moments of the backbone amide bonds in helical polypeptides are polarized either parallel or perpendicular to the helix axis. The interaction of the electric field vector of the circularly polarized light with these transitions results in an OCD spectrum of a membrane-bound α-helical peptide, which exhibits a characteristic line shape and reflects the angle between the helix axis and the bilayer normal. For parallel alignment of a peptide helix with respect to the membrane surface (S-state), the corresponding "fingerprint" CD band around 208 nm will exhibit maximum negative amplitude. If the helix changes its alignment via an obliquely tilted (T-state) to a fully inserted transmembrane orientation (I-state), the ellipticity at 208 nm decreases and the value approaches zero due to the decreased interactions between the field and the transition dipole. Compared to conventional CD, OCD data are not only collected in the biologically relevant environment of a highly hydrated planar lipid bilayer (whose composition can be varied at will), but in addition it provides information about the tilt angle of the polypeptide in the membrane. It is the method of choice for screening numerous different conditions, such as peptide concentration, lipid composition, membrane additives, pH, temperature, and sample hydration. All these factors have been found to affect the peptide alignment in membrane, while having little or no influence on conformation. In many cases, the observed realignment could be related to biological action, such as pore formation by antimicrobial and cell-penetrating peptides, or to binding events of transmembrane segments of integral membrane proteins. Likewise, any lipid-induced conversion from α-helix to β-sheeted conformation is readily picked up by OCD and has been interpreted in terms of protein instability or amyloid-formation.
Collapse
Affiliation(s)
- Jochen Bürck
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology (KIT), POB 3640, D-76021 Karlsruhe, Germany
| | - Parvesh Wadhwani
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology (KIT), POB 3640, D-76021 Karlsruhe, Germany
| | - Susanne Fanghänel
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology (KIT), POB 3640, D-76021 Karlsruhe, Germany
| | - Anne S. Ulrich
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology (KIT), POB 3640, D-76021 Karlsruhe, Germany
- Institute of Organic Chemistry, KIT, Fritz-Haber-Weg 6, D-76131 Karlsruhe, Germany
| |
Collapse
|
35
|
Brielle R, Pinel-Marie ML, Felden B. Linking bacterial type I toxins with their actions. Curr Opin Microbiol 2016; 30:114-121. [PMID: 26874964 DOI: 10.1016/j.mib.2016.01.009] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 01/18/2016] [Accepted: 01/19/2016] [Indexed: 01/12/2023]
Abstract
Bacterial type I toxin-antitoxin systems consist of stable toxin-encoding mRNAs whose expression is counteracted by unstable RNA antitoxins. Accumulating evidence suggests that these players belong to broad regulatory networks influencing overall bacterial physiology. The majority of known transmembrane type I toxic peptides have conserved structural characteristics. However, recent studies demonstrated that their mechanisms of toxicity are diverse and complex. To better assess the current state of the art, type I toxins can be grouped into two classes according to their location and mechanisms of action: membrane-associated toxins acting by pore formation and/or by nucleoid condensation; and cytosolic toxins inducing nucleic acid cleavage. This classification will evolve as a result of future investigations.
Collapse
Affiliation(s)
- Régine Brielle
- Inserm U835-Upres EA2311, Pharmaceutical Biochemistry Lab, University of Rennes 1, 2 av. du Prof. Léon Bernard, 35000 Rennes, France
| | - Marie-Laure Pinel-Marie
- Inserm U835-Upres EA2311, Pharmaceutical Biochemistry Lab, University of Rennes 1, 2 av. du Prof. Léon Bernard, 35000 Rennes, France.
| | - Brice Felden
- Inserm U835-Upres EA2311, Pharmaceutical Biochemistry Lab, University of Rennes 1, 2 av. du Prof. Léon Bernard, 35000 Rennes, France.
| |
Collapse
|
36
|
Petrauskas V, Maximowitsch E, Matulis D. Thermodynamics of Ion Pair Formations Between Charged Poly(Amino Acid)s. J Phys Chem B 2015; 119:12164-71. [PMID: 26317887 DOI: 10.1021/acs.jpcb.5b05767] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Electrostatic interactions between the positively and negatively charged amino acids in proteins play an important role in macromolecular stability, binding, and recognition. Numerous amino acids in proteins are ionizable and may exist in negatively (e.g., Glu, Asp, Cys, Tyr) or positively (e.g., Arg, Lys, His, Orn) charged form dependent on pH and their pKas. In this work, isothermal titration calorimetry was used to determine the average standard values of thermodynamic parameters (the Gibbs free energy, enthalpy, entropy, and the heat capacity) of interaction between the positively charged amino acid homopolymers (polyarginine, polylysine, and polyornithine) and the negatively charged homopolymers (polyaspartic and polyglutamic acids). These values are of potential use in the computational models of interacting proteins and other biological macromolecules. The study showed that oppositely charged poly(amino acid)s bound each other with the stoichiometry of one positive to one negative charge. Arginine bound to the negatively charged amino acids with exothermic enthalpy and higher affinity than lysine. This result also suggests that positive charges in proteins should not be considered entirely equivalent if carried by lysine or arginine. The difference in binding energy of arginine and lysine association with the negatively charged amino acids was attributed to the enthalpy of the second ionic hydrogen bond formation between the guanidine and carboxylic groups. Despite the favorable enthalpic contribution, all such ion pair formation reactions were largely entropy-driven. Consistent with previously observed ionic interactions, the positive heat capacity was always observed during the amino acid ion pair formation.
Collapse
Affiliation(s)
- Vytautas Petrauskas
- Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Vilnius University , V. A. Graičiu̅no 8, LT-02241 Vilnius, Lithuania
| | - Eglė Maximowitsch
- Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Vilnius University , V. A. Graičiu̅no 8, LT-02241 Vilnius, Lithuania
| | - Daumantas Matulis
- Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Vilnius University , V. A. Graičiu̅no 8, LT-02241 Vilnius, Lithuania
| |
Collapse
|
37
|
Dreier J, Ruggerone P. Interaction of antibacterial compounds with RND efflux pumps in Pseudomonas aeruginosa. Front Microbiol 2015; 6:660. [PMID: 26217310 PMCID: PMC4495556 DOI: 10.3389/fmicb.2015.00660] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 06/16/2015] [Indexed: 01/14/2023] Open
Abstract
Pseudomonas aeruginosa infections are becoming increasingly difficult to treat due to intrinsic antibiotic resistance and the propensity of this pathogen to accumulate diverse resistance mechanisms. Hyperexpression of efflux pumps of the Resistance-Nodulation-Cell Division (RND)-type multidrug efflux pumps (e.g., MexAB-OprM), chromosomally encoded by mexAB-oprM, mexCD-oprJ, mexEF-oprN, and mexXY (-oprA) is often detected in clinical isolates and contributes to worrying multi-drug resistance phenotypes. Not all antibiotics are affected to the same extent by the aforementioned RND efflux pumps. The impact of efflux on antibiotic activity varies not only between different classes of antibiotics but also between members of the same family of antibiotics. Subtle differences in physicochemical features of compound-pump and compound-solvent interactions largely determine how compounds are affected by efflux activity. The combination of different high-resolution techniques helps to gain insight into the functioning of these molecular machineries. This review discusses substrate recognition patterns based on experimental evidence and computer simulations with a focus on MexB, the pump subunit of the main RND transporter in P. aeruginosa.
Collapse
Affiliation(s)
- Jürg Dreier
- Basilea Pharmaceutica International Ltd.,Basel, Switzerland
| | - Paolo Ruggerone
- Dipartimento di Fisica, Università di Cagliari – Cittadella UniversitariaMonserrato, Italy
| |
Collapse
|
38
|
Brantl S, Jahn N. sRNAs in bacterial type I and type III toxin-antitoxin systems. FEMS Microbiol Rev 2015; 39:413-27. [PMID: 25808661 DOI: 10.1093/femsre/fuv003] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/20/2015] [Indexed: 01/17/2023] Open
Abstract
Toxin-antitoxin (TA) loci consist of two genes: a stable toxin whose overexpression kills the cell or causes growth stasis and an unstable antitoxin that neutralizes the toxin action. Currently, five TA systems are known. Here, we review type I and type III systems in which the antitoxins are regulatory RNAs. Type I antitoxins act by a base-pairing mechanism on toxin mRNAs. By contrast, type III antitoxins are RNA pseudoknots that bind their cognate toxins directly in an RNA-protein interaction. Whereas for a number of plasmid-encoded systems detailed information on structural requirements, kinetics of interaction with their targets and regulatory mechanisms employed by the antitoxin RNAs is available, the investigation of chromosomal systems is still in its infancy. Here, we summarize our current knowledge on that topic. Furthermore, we compare factors and conditions that induce antitoxins or toxins and different mechanisms of toxin action. Finally, we discuss biological roles for chromosome-encoded TA systems.
Collapse
Affiliation(s)
- Sabine Brantl
- AG Bakteriengenetik, Lehrstuhl für Genetik, Friedrich-Schiller-Universität Jena, Philosophenweg 12, D-07743 Jena, Germany
| | - Natalie Jahn
- AG Bakteriengenetik, Lehrstuhl für Genetik, Friedrich-Schiller-Universität Jena, Philosophenweg 12, D-07743 Jena, Germany
| |
Collapse
|
39
|
Hydrophobic mismatch demonstrated for membranolytic peptides, and their use as molecular rulers to measure bilayer thickness in native cells. Sci Rep 2015; 5:9388. [PMID: 25807192 PMCID: PMC5224518 DOI: 10.1038/srep09388] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 02/20/2015] [Indexed: 11/16/2022] Open
Abstract
Hydrophobic mismatch is a well-recognized principle in the interaction of transmembrane proteins with lipid bilayers. This concept was extended here to amphipathic membranolytic α-helices. Nine peptides with lengths between 14 and 28 amino acids were designed from repeated KIAGKIA motifs, and their helical nature was confirmed by circular dichroism spectroscopy. Biological assays for antimicrobial activity and hemolysis, as well as fluorescence vesicle leakage and solid-state NMR spectroscopy, were used to correlate peptide length with membranolytic activity. These data show that the formation of transmembrane pores is only possible under the condition of hydrophobic matching: the peptides have to be long enough to span the hydrophobic bilayer core to be able to induce vesicle leakage, kill bacteria, and cause hemolysis. By correlating the threshold lengths for biological activity with the biophysical results on model vesicles, the peptides could be utilized as molecular rulers to measure the membrane thickness in different cells.
Collapse
|
40
|
Strandberg E, Ulrich AS. AMPs and OMPs: Is the folding and bilayer insertion of β-stranded outer membrane proteins governed by the same biophysical principles as for α-helical antimicrobial peptides? BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:1944-54. [PMID: 25726906 DOI: 10.1016/j.bbamem.2015.02.019] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Revised: 02/13/2015] [Accepted: 02/18/2015] [Indexed: 11/24/2022]
Abstract
The folding and function of membrane proteins is controlled not only by specific but also by unspecific interactions with the constituent lipids. In this review, we focus on the influence of the spontaneous lipid curvature on the folding and insertion of peptides and proteins in membranes. Amphiphilic α-helical peptides, as represented by various antimicrobial sequences, are compared with β-barrel proteins, which are found in the outer membrane of Gram-negative bacteria. It has been shown that cationic amphiphilic peptides are always surface-bound in lipids with a negative spontaneous curvature like POPC, i.e. they are oriented parallel to the membrane plane. On the other hand, in lipids like DMPC with a positive curvature, these peptides can get tilted or completely inserted in a transmembrane state. Remarkably, the folding and spontaneous membrane insertion of β-barrel outer membrane proteins also proceeds more easily in lipids with a positive intrinsic curvature, while it is hampered by negative curvature. We therefore propose that a positive spontaneous curvature of the lipids promotes the ability of a surface-bound molecule to insert more deeply into the bilayer core, irrespective of the conformation, size, or shape of the peptide, protein, or folding intermediate. This article is part of a Special Issue entitled: Lipid-protein interactions.
Collapse
Affiliation(s)
- Erik Strandberg
- Karlsruhe Institute of Technology (KIT), Institute of Biological Interfaces (IBG-2), P.O.B. 3640, 76021 Karlsruhe, Germany
| | - Anne S Ulrich
- Karlsruhe Institute of Technology (KIT), Institute of Biological Interfaces (IBG-2), P.O.B. 3640, 76021 Karlsruhe, Germany; KIT, Institute of Organic Chemistry, Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany.
| |
Collapse
|
41
|
3D hydrophobic moment vectors as a tool to characterize the surface polarity of amphiphilic peptides. Biophys J 2015; 106:2385-94. [PMID: 24896117 DOI: 10.1016/j.bpj.2014.04.020] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Revised: 04/02/2014] [Accepted: 04/07/2014] [Indexed: 11/22/2022] Open
Abstract
The interaction of membranes with peptides and proteins is largely determined by their amphiphilic character. Hydrophobic moments of helical segments are commonly derived from their two-dimensional helical wheel projections, and the same is true for β-sheets. However, to the best of our knowledge, there exists no method to describe structures in three dimensions or molecules with irregular shape. Here, we define the hydrophobic moment of a molecule as a vector in three dimensions by evaluating the surface distribution of all hydrophilic and lipophilic regions over any given shape. The electrostatic potential on the molecular surface is calculated based on the atomic point charges. The resulting hydrophobic moment vector is specific for the instantaneous conformation, and it takes into account all structural characteristics of the molecule, e.g., partial unfolding, bending, and side-chain torsion angles. Extended all-atom molecular dynamics simulations are then used to calculate the equilibrium hydrophobic moments for two antimicrobial peptides, gramicidin S and PGLa, under different conditions. We show that their effective hydrophobic moment vectors reflect the distribution of polar and nonpolar patches on the molecular surface and the calculated electrostatic surface potential. A comparison of simulations in solution and in lipid membranes shows how the peptides undergo internal conformational rearrangement upon binding to the bilayer surface. A good correlation with solid-state NMR data indicates that the hydrophobic moment vector can be used to predict the membrane binding geometry of peptides. This method is available as a web application on http://www.ibg.kit.edu/HM/.
Collapse
|
42
|
Wen J, Fozo EM. sRNA antitoxins: more than one way to repress a toxin. Toxins (Basel) 2014; 6:2310-35. [PMID: 25093388 PMCID: PMC4147584 DOI: 10.3390/toxins6082310] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 07/15/2014] [Accepted: 07/17/2014] [Indexed: 11/16/2022] Open
Abstract
Bacterial toxin-antitoxin loci consist of two genes: one encodes a potentially toxic protein, and the second, an antitoxin to repress its function or expression. The antitoxin can either be an RNA or a protein. For type I and type III loci, the antitoxins are RNAs; however, they have very different modes of action. Type I antitoxins repress toxin protein expression through interacting with the toxin mRNA, thereby targeting the mRNA for degradation or preventing its translation or both; type III antitoxins directly bind to the toxin protein, sequestering it. Along with these two very different modes of action for the antitoxin, there are differences in the functions of the toxin proteins and the mobility of these loci between species. Within this review, we discuss the major differences as to how the RNAs repress toxin activity, the potential consequences for utilizing different regulatory strategies, as well as the confirmed and potential biological roles for these loci across bacterial species.
Collapse
Affiliation(s)
- Jia Wen
- Department of Microbiology, University of Tennessee, M409 Walters Life Sciences, Knoxville, TN 37996, USA.
| | - Elizabeth M Fozo
- Department of Microbiology, University of Tennessee, M409 Walters Life Sciences, Knoxville, TN 37996, USA.
| |
Collapse
|
43
|
Walther TH, Ulrich AS. Transmembrane helix assembly and the role of salt bridges. Curr Opin Struct Biol 2014; 27:63-8. [DOI: 10.1016/j.sbi.2014.05.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Revised: 05/08/2014] [Accepted: 05/09/2014] [Indexed: 10/25/2022]
|
44
|
Wadhwani P, Strandberg E, van den Berg J, Mink C, Bürck J, Ciriello RA, Ulrich AS. Dynamical structure of the short multifunctional peptide BP100 in membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:940-9. [DOI: 10.1016/j.bbamem.2013.11.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Revised: 10/25/2013] [Accepted: 11/01/2013] [Indexed: 11/26/2022]
|
45
|
Ruskamo S, Yadav RP, Sharma S, Lehtimäki M, Laulumaa S, Aggarwal S, Simons M, Bürck J, Ulrich AS, Juffer AH, Kursula I, Kursula P. Atomic resolution view into the structure-function relationships of the human myelin peripheral membrane protein P2. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2014; 70:165-76. [PMID: 24419389 PMCID: PMC3919267 DOI: 10.1107/s1399004713027910] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Accepted: 10/11/2013] [Indexed: 01/03/2023]
Abstract
P2 is a fatty acid-binding protein expressed in vertebrate peripheral nerve myelin, where it may function in bilayer stacking and lipid transport. P2 binds to phospholipid membranes through its positively charged surface and a hydrophobic tip, and accommodates fatty acids inside its barrel structure. The structure of human P2 refined at the ultrahigh resolution of 0.93 Å allows detailed structural analyses, including the full organization of an internal hydrogen-bonding network. The orientation of the bound fatty-acid carboxyl group is linked to the protonation states of two coordinating arginine residues. An anion-binding site in the portal region is suggested to be relevant for membrane interactions and conformational changes. When bound to membrane multilayers, P2 has a preferred orientation and is stabilized, and the repeat distance indicates a single layer of P2 between membranes. Simulations show the formation of a double bilayer in the presence of P2, and in cultured cells wild-type P2 induces membrane-domain formation. Here, the most accurate structural and functional view to date on P2, a major component of peripheral nerve myelin, is presented, showing how it can interact with two membranes simultaneously while going through conformational changes at its portal region enabling ligand transfer.
Collapse
Affiliation(s)
- Salla Ruskamo
- Department of Biochemistry, University of Oulu, Oulu, Finland
- Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Ravi P. Yadav
- Molecular Biology Unit, Institute of Medical Sciences (IMS), Banaras Hindu University, Varanasi, India
- Centre for Structural Systems Biology, Helmholtz Centre for Infection Research (CSSB-HZI), German Electron Synchrotron (DESY), Hamburg, Germany
| | - Satyan Sharma
- Department of Biochemistry, University of Oulu, Oulu, Finland
- Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Mari Lehtimäki
- Department of Biochemistry, University of Oulu, Oulu, Finland
- Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Saara Laulumaa
- Department of Biochemistry, University of Oulu, Oulu, Finland
- Biocenter Oulu, University of Oulu, Oulu, Finland
- Centre for Structural Systems Biology, Helmholtz Centre for Infection Research (CSSB-HZI), German Electron Synchrotron (DESY), Hamburg, Germany
| | - Shweta Aggarwal
- Max Planck Institute for Experimental Medicine, Göttingen, Germany
| | - Mikael Simons
- Max Planck Institute for Experimental Medicine, Göttingen, Germany
| | - Jochen Bürck
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute for Technology (KIT), Karlsruhe, Germany
| | - Anne S. Ulrich
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute for Technology (KIT), Karlsruhe, Germany
| | - André H. Juffer
- Department of Biochemistry, University of Oulu, Oulu, Finland
- Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Inari Kursula
- Department of Biochemistry, University of Oulu, Oulu, Finland
- Centre for Structural Systems Biology, Helmholtz Centre for Infection Research (CSSB-HZI), German Electron Synchrotron (DESY), Hamburg, Germany
| | - Petri Kursula
- Department of Biochemistry, University of Oulu, Oulu, Finland
- Biocenter Oulu, University of Oulu, Oulu, Finland
- Centre for Structural Systems Biology, Helmholtz Centre for Infection Research (CSSB-HZI), German Electron Synchrotron (DESY), Hamburg, Germany
- Department of Chemistry, University of Hamburg, Hamburg, Germany
| |
Collapse
|
46
|
Muruganandam G, Bürck J, Ulrich AS, Kursula I, Kursula P. Lipid membrane association of myelin proteins and peptide segments studied by oriented and synchrotron radiation circular dichroism spectroscopy. J Phys Chem B 2013; 117:14983-93. [PMID: 24236572 DOI: 10.1021/jp4098588] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Myelin-specific proteins are either integral or peripheral membrane proteins that, in complex with lipids, constitute a multilayered proteolipid membrane system, the myelin sheath. The myelin sheath surrounds the axons of nerves and enables rapid conduction of axonal impulses. Myelin proteins interact intimately with the lipid bilayer and play crucial roles in the assembly, function, and stability of the myelin sheath. Although myelin proteins have been investigated for decades, their structural properties upon membrane surface binding are still largely unknown. In this study, we have used simplified model systems consisting of synthetic peptides and membrane mimics, such as detergent micelles and/or lipid vesicles, to probe the conformation of peptides using synchrotron radiation circular dichroism spectroscopy (SRCD). Additionally, oriented circular dichroism spectroscopy (OCD) was employed to examine the orientation of myelin peptides in macroscopically aligned lipid bilayers. Various representative peptides from the myelin basic protein (MBP), P0, myelin/oligodencrocyte glycoprotein, and connexin32 (cx32) were studied. A helical peptide from the central immunodominant epitope of MBP showed a highly tilted orientation with respect to the membrane surface, whereas the N-terminal cytoplasmic segment of cx32 folded into a helical structure that was only slightly tilted. The folding of full-length myelin basic protein was, furthermore, studied in a bicelle environment. Our results provide information on the conformation and membrane alignment of important membrane-binding peptides in a membrane-mimicking environment, giving novel insights into the mechanisms of membrane binding and stacking by myelin proteins.
Collapse
Affiliation(s)
- Gopinath Muruganandam
- Centre for Structural Systems Biology, Helmholtz Centre for Infection Research (CSSB-HZI) , German Electron Synchrotron (DESY), Hamburg 22607, Germany
| | | | | | | | | |
Collapse
|
47
|
Coarse-grain modelling of protein-protein interactions. Curr Opin Struct Biol 2013; 23:878-86. [PMID: 24172141 DOI: 10.1016/j.sbi.2013.09.004] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 08/29/2013] [Accepted: 09/17/2013] [Indexed: 11/24/2022]
Abstract
Here, we review recent advances towards the modelling of protein-protein interactions (PPI) at the coarse-grained (CG) level, a technique that is now widely used to understand protein affinity, aggregation and self-assembly behaviour. PPI models of soluble proteins and membrane proteins are separately described, but we note the parallel development that is present in both research fields with three important themes: firstly, combining CG modelling with knowledge-based approaches to predict and refine protein-protein complexes; secondly, using physics-based CG models for de novo prediction of protein-protein complexes; and thirdly modelling of large scale protein aggregates.
Collapse
|
48
|
Walther TH, Gottselig C, Grage SL, Wolf M, Vargiu AV, Klein MJ, Vollmer S, Prock S, Hartmann M, Afonin S, Stockwald E, Heinzmann H, Nolandt OV, Wenzel W, Ruggerone P, Ulrich AS. Folding and self-assembly of the TatA translocation pore based on a charge zipper mechanism. Cell 2013; 152:316-26. [PMID: 23332763 DOI: 10.1016/j.cell.2012.12.017] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Revised: 08/20/2012] [Accepted: 12/13/2012] [Indexed: 12/11/2022]
Abstract
We propose a concept for the folding and self-assembly of the pore-forming TatA complex from the Twin-arginine translocase and of other membrane proteins based on electrostatic "charge zippers." Each subunit of TatA consists of a transmembrane segment, an amphiphilic helix (APH), and a C-terminal densely charged region (DCR). The sequence of charges in the DCR is complementary to the charge pattern on the APH, suggesting that the protein can be "zipped up" by a ladder of seven salt bridges. The length of the resulting hairpin matches the lipid bilayer thickness, hence a transmembrane pore could self-assemble via intra- and intermolecular salt bridges. The steric feasibility was rationalized by molecular dynamics simulations, and experimental evidence was obtained by monitoring the monomer-oligomer equilibrium of specific charge mutants. Similar "charge zippers" are proposed for other membrane-associated proteins, e.g., the biofilm-inducing peptide TisB, the human antimicrobial peptide dermcidin, and the pestiviral E(RNS) protein.
Collapse
Affiliation(s)
- Torsten H Walther
- Karlsruhe Institute of Technology, Institute of Biological Interfaces, Institute of Organic Chemistry and CFN, Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
49
|
|