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Lehman KM, Grabowicz M. Countering Gram-Negative Antibiotic Resistance: Recent Progress in Disrupting the Outer Membrane with Novel Therapeutics. Antibiotics (Basel) 2019; 8:antibiotics8040163. [PMID: 31554212 PMCID: PMC6963605 DOI: 10.3390/antibiotics8040163] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 09/19/2019] [Accepted: 09/20/2019] [Indexed: 10/27/2022] Open
Abstract
Gram-negative bacteria shield themselves from antibiotics by producing an outer membrane (OM) that forms a formidable permeability barrier. Multidrug resistance among these organisms is a particularly acute problem that is exacerbated by the OM. The poor penetrance of many available antibiotics prevents their clinical use, and efforts to discover novel classes of antibiotics against Gram-negative bacteria have been unsuccessful for almost 50 years. Recent insights into how the OM is built offer new hope. Several essential multiprotein molecular machines (Bam, Lpt, and Lol) work in concert to assemble the barrier and offer a swathe of new targets for novel therapeutic development. Murepavadin has been at the vanguard of these efforts, but its recently reported phase III clinical trial toxicity has tempered the anticipation of imminent new clinical options. Nonetheless, the many concerted efforts aimed at breaking down the OM barrier provide a source of ongoing optimism for what may soon come through the development pipeline. We will review the current state of drug development against the OM assembly targets, highlighting insightful new discovery approaches and strategies.
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Affiliation(s)
- Kelly M Lehman
- Microbiology and Molecular Genetics Program, Graduate Division of Biological and Biomedical Sciences, Laney Graduate School, Emory University, Atlanta, GA 30322, USA.
- Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA 30322, USA.
- Department of Microbiology & Immunology, Emory University School of Medicine, Atlanta, GA 30322, USA.
| | - Marcin Grabowicz
- Microbiology and Molecular Genetics Program, Graduate Division of Biological and Biomedical Sciences, Laney Graduate School, Emory University, Atlanta, GA 30322, USA.
- Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA 30322, USA.
- Department of Microbiology & Immunology, Emory University School of Medicine, Atlanta, GA 30322, USA.
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA.
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52
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Singh W, Bilal M, McClory J, Dourado D, Quinn D, Moody TS, Sutcliffe I, Huang M. Mechanism of Phosphatidylglycerol Activation Catalyzed by Prolipoprotein Diacylglyceryl Transferase. J Phys Chem B 2019; 123:7092-7102. [DOI: 10.1021/acs.jpcb.9b04227] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Warispreet Singh
- School of Chemistry & Chemical Engineering, Queen’s University Belfast, Belfast BT9 5AG, Northern Ireland, United Kingdom
- Department of Biocatalysis and Isotope Chemistry, Almac Sciences, Almac House, 20 Seagoe Industrial Estate, Craigavon BT63 5QD, Northern Ireland, United Kingdom
| | - Munir Bilal
- Department of Applied Sciences, Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne NE1 8ST, United Kingdom
| | - James McClory
- School of Chemistry & Chemical Engineering, Queen’s University Belfast, Belfast BT9 5AG, Northern Ireland, United Kingdom
| | - Daniel Dourado
- School of Chemistry & Chemical Engineering, Queen’s University Belfast, Belfast BT9 5AG, Northern Ireland, United Kingdom
- Department of Biocatalysis and Isotope Chemistry, Almac Sciences, Almac House, 20 Seagoe Industrial Estate, Craigavon BT63 5QD, Northern Ireland, United Kingdom
| | - Derek Quinn
- Department of Biocatalysis and Isotope Chemistry, Almac Sciences, Almac House, 20 Seagoe Industrial Estate, Craigavon BT63 5QD, Northern Ireland, United Kingdom
| | - Thomas S. Moody
- Department of Biocatalysis and Isotope Chemistry, Almac Sciences, Almac House, 20 Seagoe Industrial Estate, Craigavon BT63 5QD, Northern Ireland, United Kingdom
- Arran Chemical Company Limited, Unit 1 Monksland Industrial Estate, Athlone, Co., Roscommon, N37 DN24, Ireland
| | - Iain Sutcliffe
- Department of Applied Sciences, Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne NE1 8ST, United Kingdom
| | - Meilan Huang
- School of Chemistry & Chemical Engineering, Queen’s University Belfast, Belfast BT9 5AG, Northern Ireland, United Kingdom
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53
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Abstract
Lipoproteins are produced by both Gram-positive and Gram-negative bacteria. Once secreted, lipoproteins are quickly acylated, anchoring them into the plasma membrane. Recent work has shown that Gram-positive bacteria are able to generate considerable diversity in the acylation of their lipoproteins, though the mechanisms involved are only just beginning to emerge. In Gram-negative organisms, most lipoproteins are subsequently trafficked to the outer membrane (OM). Lipoprotein trafficking is an essential pathway in these bacteria. At least one OM lipoprotein component is required by each of the essential machines that assemble the OM (such as the Bam and Lpt machines) and build the peptidoglycan cell wall (Lpo-penicillin-binding protein complexes). The Lol pathway has been the paradigm for OM lipoprotein trafficking: a complex of LolCDE extracts lipoproteins from the plasma membrane, LolA shuttles them through the periplasmic space, and LolB anchors them into the OM. The peptide signals responsible for OM-targeting via LolCDE have long been known for Escherichia coli. Remarkably, production of novel lipoprotein acyl forms in E. coli has reinforced the idea that lipid signals also contribute to OM targeting via LolCDE. Moreover, recent work has shown that lipoprotein trafficking can occur in E. coli without either LolA or LolB. Therefore, current evidence suggests that at least one additional, LolAB-independent route for OM lipoprotein trafficking exists. This chapter reviews the posttranslocation modifications of all lipoproteins, with a focus on the trafficking of lipoproteins to the OM of Gram-negative bacteria.
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54
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Evidence to Suggest Bacterial Lipoprotein Diacylglyceryl Transferase (Lgt) is a Weakly Associated Inner Membrane Protein. J Membr Biol 2019; 252:563-575. [DOI: 10.1007/s00232-019-00076-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 06/14/2019] [Indexed: 10/26/2022]
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Abstract
The outer membrane built by Gram-negative bacteria such as Escherichia coli forms a barrier that prevents antibiotics from entering the cell, limiting clinical options at a time of prevalent antibiotic resistance. Stress responses ensure that barrier integrity is continuously maintained. We have identified the Cpx signal transduction system as a stress response that monitors the trafficking of lipid-anchored lipoproteins to the outer membrane. These lipoproteins are needed by every machine that builds the outer membrane. Cpx monitors just one lipoprotein, NlpE, to detect the efficiency of lipoprotein trafficking in the cell. NlpE and Cpx were previously shown to play a role in resistance to copper. We show that copper blocks lipoprotein trafficking, reconciling old and new observations. Copper is an important element in innate immunity against pathogens, and our findings suggest that NlpE and Cpx help E. coli survive the assault of copper on a key outer membrane assembly pathway. Gram-negative bacteria produce lipid-anchored lipoproteins that are trafficked to their outer membrane (OM). These lipoproteins are essential components in each of the molecular machines that build the OM, including the Bam machine that assembles β-barrel proteins and the Lpt pathway that transports lipopolysaccharide. Stress responses are known to monitor Bam and Lpt function, yet no stress system has been found that oversees the fundamental process of lipoprotein trafficking. We used genetic and chemical biology approaches to induce several different lipoprotein trafficking stresses in Escherichia coli. Our results identified the Cpx two-component system as a stress response for monitoring trafficking. Cpx is activated by trafficking defects and is required to protect the cell against the consequence of the resulting stress. The OM-targeted lipoprotein NlpE acts as a sensor that allows Cpx to gauge trafficking efficiency. We reveal that NlpE signals to Cpx while it is transiting the inner membrane (IM) en route to the OM and that only a small highly conserved N-terminal domain is required for signaling. We propose that defective trafficking causes NlpE to accumulate in the IM, activating Cpx to mount a transcriptional response that protects cells. Furthermore, we reconcile this new role of NlpE in signaling trafficking defects with its previously proposed role in sensing copper (Cu) stress by demonstrating that Cu impairs acylation of lipoproteins and, consequently, their trafficking to the OM.
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56
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El Arnaout T, Soulimane T. Targeting Lipoprotein Biogenesis: Considerations towards Antimicrobials. Trends Biochem Sci 2019; 44:701-715. [PMID: 31036406 DOI: 10.1016/j.tibs.2019.03.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 03/14/2019] [Accepted: 03/25/2019] [Indexed: 12/25/2022]
Abstract
Decades have passed without approval of a new antibiotic class. Several companies have recently halted related discovery efforts because of multiple obstacles. One promising route under research is to target the lipoprotein maturation pathway in light of major recent findings and the virulence roles of lipoproteins. To support the future design of selective drugs, considerations and priority-setting are established for the main lipoprotein processing enzymes (Lgt, LspA, and Lnt) based on microbiology, biochemistry, structural biology, chemical design, and pharmacology. Although not all bacterial species will be similarly impacted by drug candidates, several advantages make LspA a top target to pursue in the development of novel antibiotics effective against bacteria that are resistant to existing drugs.
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Affiliation(s)
- Toufic El Arnaout
- Kappa Crystals Ltd, Dublin, Ireland; School of Food Science and Environmental Health, Technological University (TU) Dublin City Campus, TU, Dublin, Dublin, Ireland.
| | - Tewfik Soulimane
- Bernal Institute, University of Limerick, Limerick, V94 T9PX, Ireland; Department of Chemical Sciences, University of Limerick, Limerick, V94 T9PX, Ireland
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57
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The Lipoprotein NlpE Is a Cpx Sensor That Serves as a Sentinel for Protein Sorting and Folding Defects in the Escherichia coli Envelope. J Bacteriol 2019; 201:JB.00611-18. [PMID: 30833359 DOI: 10.1128/jb.00611-18] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 03/01/2019] [Indexed: 12/18/2022] Open
Abstract
The envelope of Gram-negative bacteria is a complex compartment that is essential for viability. To ensure survival of the bacterial cells in fluctuating environments, several signal transduction systems, called envelope stress response systems (ESRSs), exist to monitor envelope biogenesis and homeostasis. The Cpx two-component system is an extensively studied ESRS in Escherichia coli that is active during exposure to a vast array of stresses and protects the envelope under those harmful circumstances. Overproduction of NlpE, a two-domain outer membrane lipoprotein of unclear function, has been used in numerous studies as a molecular trigger to turn on the system artificially. However, the mechanism of Cpx activation by NlpE, as well as its physiological relevance, awaited further investigation. In this paper, we provide novel insights into the role played by NlpE in the Cpx system. We found that, among all outer membrane lipoproteins in E. coli, NlpE is sufficient to induce Cpx when lipoprotein trafficking is perturbed. Under such conditions, fitness is increased by the presence of NlpE. Moreover, we show that NlpE, through its N-terminal domain, physically interacts with the Cpx sensor kinase CpxA. Our data suggest that NlpE also serves to activate the Cpx system during oxidative folding defects in the periplasm and that its C-terminal domain is involved in the sensing mechanism. Overall, our data demonstrate that NlpE acts as a sentinel for two important envelope biogenesis processes, namely, lipoprotein sorting and oxidative folding, and they further establish NlpE as a bona fide member of the Cpx two-component system.IMPORTANCE Bacteria rely on a sophisticated envelope to shield them against challenging environmental conditions and therefore need to ensure correct envelope assembly and integrity. A major signaling pathway that performs this role in Gram-negative species is the Cpx system. An outer membrane lipoprotein of unclear function, NlpE, has long been exploited as a research tool to study Cpx in E. coli, since it triggers this system when overproduced or mislocalized; however, the mechanism and physiological relevance of the NlpE-Cpx connection have awaited further investigation. We elucidate a new function for NlpE by showing that it physically interacts with the Cpx sensor CpxA and acts as a sentinel that specifically monitors two essential envelope biogenesis processes, namely, lipoprotein sorting and oxidative folding.
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58
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Abstract
Signal peptidases are the membrane bound enzymes that cleave off the amino-terminal signal peptide from secretory preproteins . There are two types of bacterial signal peptidases . Type I signal peptidase utilizes a serine/lysine catalytic dyad mechanism and is the major signal peptidase in most bacteria. Type II signal peptidase is an aspartic protease specific for prolipoproteins. This chapter will review what is known about the structure, function and mechanism of these unique enzymes.
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Affiliation(s)
- Mark Paetzel
- Department of Molecular Biology and Biochemistry, Simon Fraser University, South Science Building 8888 University Drive, Burnaby, BC, V5A 1S6, Canada.
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59
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Abstract
The Lpp lipoprotein of Escherichia coli is the first identified protein with a covalently linked lipid. It is chemically bound by its C-terminus to murein (peptidoglycan) and inserts by the lipid at the N-terminus into the outer membrane. As the most abundant protein in E. coli (106 molecules per cell) it plays an important role for the integrity of the cell envelope. Lpp represents the type protein of a large variety of lipoproteins found in Gram-negative and Gram-positive bacteria and in archaea that have in common the lipid structure for anchoring the proteins to membranes but otherwise strongly vary in sequence, structure, and function. Predicted lipoproteins in known prokaryotic genomes comprise 2.7% of all proteins. Lipoproteins are modified by a unique phospholipid pathway and transferred from the cytoplasmic membrane into the outer membrane by a special system. They are involved in protein incorporation into the outer membrane, protein secretion across the cytoplasmic membrane, periplasm and outer membrane, signal transduction, conjugation, cell wall metabolism, antibiotic resistance, biofilm formation, and adhesion to host tissues. They are only found in bacteria and function as signal molecules for the innate immune system of vertebrates, where they cause inflammation and elicit innate and adaptive immune response through Toll-like receptors. This review discusses various aspects of Lpp and other lipoproteins of Gram-negative and Gram-positive bacteria and archaea.
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Affiliation(s)
- Volkmar Braun
- Department of Protein Evolution, Max Planck Institute for Developmental Biology, Max Planck Ring 5, 72076, Tübingen, Germany.
| | - Klaus Hantke
- IMIT, University of Tuebingen, Auf der Morgenstelle 28, 72076, Tübingen, Germany
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60
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Abdel Monaim SAH, Somboro AM, El-Faham A, de la Torre BG, Albericio F. Bacteria Hunt Bacteria through an Intriguing Cyclic Peptide. ChemMedChem 2018; 14:24-51. [PMID: 30394699 DOI: 10.1002/cmdc.201800597] [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: 09/04/2018] [Revised: 10/10/2018] [Indexed: 12/15/2022]
Abstract
In the last few decades, peptides have been victorious over small molecules as therapeutics due to their broad range of applications, high biological activity, and high specificity. However, the main challenges to overcome if peptides are to become effective drugs is their low oral bioavailability and instability under physiological conditions. Cyclic peptides play a vital role in this context because they show higher stability under physiological conditions, higher membrane permeability, and greater oral bioavailability than that of their corresponding linear analogues. In this regard, cyclic antimicrobial peptides (AMPs) have gained considerable attention in the field of novel antibiotic development. Bacterial strains produce cyclic AMPs through two pathways: ribosomal and nonribosomal. This review provides an overview of the chemical classification of cyclic AMPs isolated from bacteria, and provides a description of their biological activity and mode of action.
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Affiliation(s)
- Shimaa A H Abdel Monaim
- KwaZulu-Natal Research Innovation and Sequencing Platform (KRISP), School of Laboratory Medicine and Medical Sciences, College of Health Sciences, University of KwaZulu-Natal, Durban, 4041, South Africa.,Peptide Science Laboratory, School of Chemistry and Physics, University of KwaZulu-Natal, Durban, 4001, South Africa
| | - Anou M Somboro
- Biomedical Resource Unit, School of Laboratory Medicine and Medical Sciences, College of Health Sciences, University of KwaZulu-Natal, Durban, 4041, South Africa
| | - Ayman El-Faham
- Department of Chemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh, 11451, Saudi Arabia.,Chemistry Department, Faculty of Science, Alexandria University, P.O. Box 426, Ibrahimia, Alexandria, 12321, Egypt
| | - Beatriz G de la Torre
- KwaZulu-Natal Research Innovation and Sequencing Platform (KRISP), School of Laboratory Medicine and Medical Sciences, College of Health Sciences, University of KwaZulu-Natal, Durban, 4041, South Africa
| | - Fernando Albericio
- Peptide Science Laboratory, School of Chemistry and Physics, University of KwaZulu-Natal, Durban, 4001, South Africa.,Department of Chemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh, 11451, Saudi Arabia.,CIBER-BBN, Networking Centre on Bioengineering, Biomaterials and Nanomedicine, and Department of Organic Chemistry, University of Barcelona, Barcelona, 08028, Spain
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61
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Boland C, Olatunji S, Bailey J, Howe N, Weichert D, Fetics SK, Yu X, Merino-Gracia J, Delsaut C, Caffrey M. Membrane (and Soluble) Protein Stability and Binding Measurements in the Lipid Cubic Phase Using Label-Free Differential Scanning Fluorimetry. Anal Chem 2018; 90:12152-12160. [DOI: 10.1021/acs.analchem.8b03176] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Coilín Boland
- School of Medicine and School of Biochemistry and Immunology, Trinity College Dublin DO2 R590, Ireland
| | - Samir Olatunji
- School of Medicine and School of Biochemistry and Immunology, Trinity College Dublin DO2 R590, Ireland
| | - Jonathan Bailey
- School of Medicine and School of Biochemistry and Immunology, Trinity College Dublin DO2 R590, Ireland
| | - Nicole Howe
- School of Medicine and School of Biochemistry and Immunology, Trinity College Dublin DO2 R590, Ireland
| | - Dietmar Weichert
- School of Medicine and School of Biochemistry and Immunology, Trinity College Dublin DO2 R590, Ireland
| | - Susan Kathleen Fetics
- School of Medicine and School of Biochemistry and Immunology, Trinity College Dublin DO2 R590, Ireland
| | - Xiaoxiao Yu
- School of Medicine and School of Biochemistry and Immunology, Trinity College Dublin DO2 R590, Ireland
| | - Javier Merino-Gracia
- School of Medicine and School of Biochemistry and Immunology, Trinity College Dublin DO2 R590, Ireland
| | - Clement Delsaut
- School of Medicine and School of Biochemistry and Immunology, Trinity College Dublin DO2 R590, Ireland
| | - Martin Caffrey
- School of Medicine and School of Biochemistry and Immunology, Trinity College Dublin DO2 R590, Ireland
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62
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Huang CY, Olieric V, Howe N, Warshamanage R, Weinert T, Panepucci E, Vogeley L, Basu S, Diederichs K, Caffrey M, Wang M. In situ serial crystallography for rapid de novo membrane protein structure determination. Commun Biol 2018; 1:124. [PMID: 30272004 PMCID: PMC6123769 DOI: 10.1038/s42003-018-0123-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 07/19/2018] [Indexed: 11/30/2022] Open
Abstract
De novo membrane protein structure determination is often limited by the availability of large crystals and the difficulties in obtaining accurate diffraction data for experimental phasing. Here we present a method that combines in situ serial crystallography with de novo phasing for fast, efficient membrane protein structure determination. The method enables systematic diffraction screening and rapid data collection from hundreds of microcrystals in in meso crystallization wells without the need for direct crystal harvesting. The requisite data quality for experimental phasing is achieved by accumulating diffraction signals from isomorphous crystals identified post-data collection. The method works in all experimental phasing scenarios and is particularly attractive with fragile, weakly diffracting microcrystals. The automated serial data collection approach can be readily adopted at most microfocus macromolecular crystallography beamlines.
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Affiliation(s)
- Chia-Ying Huang
- Swiss Light Source, Paul Scherrer Institute, CH-5232, Villigen, Switzerland
| | - Vincent Olieric
- Swiss Light Source, Paul Scherrer Institute, CH-5232, Villigen, Switzerland
| | - Nicole Howe
- Membrane Structural and Functional Biology (MS&FB) Group, School of Medicine and School of Biochemistry and Immunology, Trinity College Dublin, Dublin 2, D02 R590, Ireland
| | | | - Tobias Weinert
- Swiss Light Source, Paul Scherrer Institute, CH-5232, Villigen, Switzerland
| | - Ezequiel Panepucci
- Swiss Light Source, Paul Scherrer Institute, CH-5232, Villigen, Switzerland
| | - Lutz Vogeley
- Membrane Structural and Functional Biology (MS&FB) Group, School of Medicine and School of Biochemistry and Immunology, Trinity College Dublin, Dublin 2, D02 R590, Ireland
| | - Shibom Basu
- Swiss Light Source, Paul Scherrer Institute, CH-5232, Villigen, Switzerland
| | - Kay Diederichs
- Fachbereich Biologie, Universität Konstanz, M647, D-78457, Konstanz, Germany
| | - Martin Caffrey
- Membrane Structural and Functional Biology (MS&FB) Group, School of Medicine and School of Biochemistry and Immunology, Trinity College Dublin, Dublin 2, D02 R590, Ireland.
| | - Meitian Wang
- Swiss Light Source, Paul Scherrer Institute, CH-5232, Villigen, Switzerland.
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63
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Kitamura S, Wolan DW. Probing substrate recognition of bacterial lipoprotein signal peptidase using FRET reporters. FEBS Lett 2018; 592:2289-2296. [DOI: 10.1002/1873-3468.13155] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 05/10/2018] [Accepted: 05/30/2018] [Indexed: 12/15/2022]
Affiliation(s)
- Seiya Kitamura
- Department of Molecular Medicine; The Scripps Research Institute; La Jolla CA USA
- Department of Integrative Structural and Computational Biology; The Scripps Research Institute; La Jolla CA USA
| | - Dennis W. Wolan
- Department of Molecular Medicine; The Scripps Research Institute; La Jolla CA USA
- Department of Integrative Structural and Computational Biology; The Scripps Research Institute; La Jolla CA USA
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64
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Cheng W, Doyle DA, El Arnaout T. The N-acyltransferase Lnt: Structure-function insights from recent simultaneous studies. Int J Biol Macromol 2018; 117:870-877. [PMID: 29859843 DOI: 10.1016/j.ijbiomac.2018.05.229] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 05/29/2018] [Accepted: 05/30/2018] [Indexed: 02/05/2023]
Abstract
Bacterial lipoproteins have been researched for decades due to their roles in a large number of biological functions. There were no structures of their main three membrane processing enzymes, until 2016 for Lgt and LspA, and then 2017 for Lnt with not one but three simultaneous, independent publications. We have analyzed the recent findings for this apolipoprotein N-acyltransferase Lnt, with comparisons between the novel structures, and with soluble nitrilases, to determine the significance of unique features in terms of substrate's recognition and binding mechanism influenced by exclusive residues, two transmembrane helices, and a flexible loop.
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Affiliation(s)
- Wei Cheng
- Division of Respiratory and Critical Care Medicine, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University and Collaborative Innovation Center of Biotherapy, Chengdu, Sichuan 610041, China
| | - Declan A Doyle
- Biological Sciences, University of Southampton, Southampton SO17 1BJ, UK
| | - Toufic El Arnaout
- School of Food Science and Environmental Health, Dublin Institute of Technology, Marlborough St, Dublin 1, Ireland.
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65
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Biophysical characterization and stabilization of detergent-solubilized lipoprotein N-acyl transferase from P. aeruginosa and E. coli. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1384-1393. [PMID: 29573991 DOI: 10.1016/j.bbamem.2018.03.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 03/18/2018] [Accepted: 03/20/2018] [Indexed: 11/23/2022]
Abstract
Lipoproteins are important for bacterial growth and virulence and interest in them as targets for antibiotic development is growing. Lipoprotein N-acyl transferase (Lnt) catalyzes the final step in the lipoprotein posttranslational processing pathway. The mature lipoprotein can remain in the inner membrane or be trafficked to the outer membrane in the case of diderm prokaryotes. With a view to obtaining high-resolution crystal structures of membrane integral Lnt for use in drug discovery a program was undertaken to generate milligram quantities of stable, homogenous and functional protein. This involved screening across bacterial species for suitable orthologues and optimization at the level of protein expression, solubilization and stability. Combining biophysical and functional characterization, orthologous Lnt from Escherichia coli and the opportunistic human pathogen Pseudomonas aeruginosa was identified as suitable for the proposed structure determination campaign that ultimately yielded crystal structures. The rational approaches taken that eventually provided structure-quality protein are presented in this report.
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66
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Translocation of lipoproteins to the surface of gram negative bacteria. Curr Opin Struct Biol 2018; 51:73-79. [PMID: 29579694 DOI: 10.1016/j.sbi.2018.03.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 03/06/2018] [Accepted: 03/07/2018] [Indexed: 11/21/2022]
Abstract
The surface of many Gram-negative bacteria contains lipidated protein molecules referred to as surface lipoproteins or SLPs. SLPs play critical roles in host immune evasion, nutrient acquisition and regulation of bacterial stress response, and have been extensively studied as vaccine antigens. The aim of this review is to summarize the recent studies that have investigated the biosynthetic and translocation pathways used by different bacterial species to deliver SLPs to the surface. We will specifically focus on Slam, a novel outer membrane protein first discovered in pathogenic Neisseria sp., that is involved in translocation of SLPs across the outer membrane.
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67
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Affiliation(s)
- Marcin Grabowicz
- Department of Microbiology and Immunology; Emory University School of Medicine; Atlanta GA 30322 USA
- Division of Infectious Disease; Department of Medicine; Emory University School of Medicine; Atlanta GA 30322 USA
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68
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Kitamura S, Owensby A, Wall D, Wolan DW. Lipoprotein Signal Peptidase Inhibitors with Antibiotic Properties Identified through Design of a Robust In Vitro HT Platform. Cell Chem Biol 2018; 25:301-308.e12. [PMID: 29337186 DOI: 10.1016/j.chembiol.2017.12.011] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 11/09/2017] [Accepted: 12/19/2017] [Indexed: 11/29/2022]
Abstract
As resistance to antibiotics increases, the exploration of new targets and strategies to combat pathogenic bacteria becomes more urgent. Ideal protein targets are required for viability across many species, are unique to prokaryotes to limit effects on the host, and have robust assays to quantitate activity and identify inhibitors. Lipoprotein signal peptidase (Lsp) is a transmembrane aspartyl protease required for lipoprotein maturation and comprehensively fits these criteria. Here, we have developed the first in vitro high-throughput assay to monitor proteolysis by Lsp. We employed our high-throughput screen assay against 646,275 compounds to discover inhibitors of Lsp and synthesized a range of analogs to generate molecules with nanomolar half maximal inhibitory concentration values. Importantly, our inhibitors are effective in preventing the growth of E. coli cultures in the presence of outer-membrane permeabilizer PMBN and should facilitate development of antibacterial agents with a novel mechanism of action to treat antibiotic-resistant bacteria.
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Affiliation(s)
- Seiya Kitamura
- Department of Molecular Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Anna Owensby
- Department of Molecular Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Daniel Wall
- Department of Molecular Biology, University of Wyoming, 1000 East University Avenue, Laramie, WY 82071, USA
| | - Dennis W Wolan
- Department of Molecular Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
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69
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Li Z, Tang Y, Wu Y, Zhao S, Bao J, Luo Y, Li D. Structural insights into the committed step of bacterial phospholipid biosynthesis. Nat Commun 2017; 8:1691. [PMID: 29167463 PMCID: PMC5700162 DOI: 10.1038/s41467-017-01821-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 10/18/2017] [Indexed: 11/09/2022] Open
Abstract
The membrane-integral glycerol 3-phosphate (G3P) acyltransferase PlsY catalyses the committed and essential step in bacterial phospholipid biosynthesis by acylation of G3P, forming lysophosphatidic acid. It contains no known acyltransferase motifs, lacks eukaryotic homologs, and uses the unusual acyl-phosphate as acyl donor, as opposed to acyl-CoA or acyl-carrier protein for other acyltransferases. Previous studies have identified several PlsY inhibitors as potential antimicrobials. Here we determine the crystal structure of PlsY at 1.48 Å resolution, revealing a seven-transmembrane helix fold. Four additional substrate- and product-bound structures uncover the atomic details of its relatively inflexible active site. Structure and mutagenesis suggest a different acylation mechanism of ‘substrate-assisted catalysis’ that, unlike other acyltransferases, does not require a proteinaceous catalytic base to complete. The structure data and a high-throughput enzymatic assay developed in this work should prove useful for virtual and experimental screening of inhibitors against this vital bacterial enzyme. The first step in bacterial phospholipid biosynthesis is the acylation of glycerol 3-phosphate to form lysophosphatidic acid. Here, the authors present the high resolution crystal structure of the glycerol 3-phosphate acyltransferase PlsY, a membrane protein and give insights into its catalytical mechanism.
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Affiliation(s)
- Zhenjian Li
- State Key Laboratory of Molecular Biology, National Center for Protein Science Shanghai, Shanghai Science Research Center, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, 333 Haike Road, Shanghai, 201210, China
| | - Yannan Tang
- State Key Laboratory of Molecular Biology, National Center for Protein Science Shanghai, Shanghai Science Research Center, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, 333 Haike Road, Shanghai, 201210, China.,University of Chinese Academy of Sciences, Shanghai, 201210, China
| | - Yiran Wu
- iHuman Institute, ShanghaiTech University, 333 Middle Huaxia Road, Shanghai, 201210, China
| | - Suwen Zhao
- iHuman Institute, ShanghaiTech University, 333 Middle Huaxia Road, Shanghai, 201210, China.,School of Life Science and Technology, ShanghaiTech University, 333 Middle Huaxia Road, Shanghai, 201210, China
| | - Juan Bao
- State Key Laboratory of Molecular Biology, National Center for Protein Science Shanghai, Shanghai Science Research Center, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, 333 Haike Road, Shanghai, 201210, China
| | - Yitian Luo
- State Key Laboratory of Molecular Biology, National Center for Protein Science Shanghai, Shanghai Science Research Center, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, 333 Haike Road, Shanghai, 201210, China.,University of Chinese Academy of Sciences, Shanghai, 201210, China.,School of Life Science and Technology, ShanghaiTech University, 333 Middle Huaxia Road, Shanghai, 201210, China
| | - Dianfan Li
- State Key Laboratory of Molecular Biology, National Center for Protein Science Shanghai, Shanghai Science Research Center, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, 333 Haike Road, Shanghai, 201210, China.
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70
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Peetz O, Henrich E, Laguerre A, Löhr F, Hein C, Dötsch V, Bernhard F, Morgner N. Insights into Cotranslational Membrane Protein Insertion by Combined LILBID-Mass Spectrometry and NMR Spectroscopy. Anal Chem 2017; 89:12314-12318. [PMID: 29039652 DOI: 10.1021/acs.analchem.7b03309] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cotranslational insertion of membrane proteins into defined nanoparticle membranes has been developed as an efficient process to produce highly soluble samples in native-like environments and to study lipid-dependent effects on protein structure and function. Numerous examples of the structural and functional characterization of transporters, ion channels, or G-protein-coupled receptors in cotranslationally formed nanodisc complexes demonstrate the versatility of this approach, although the basic underlying mechanisms of membrane insertion are mainly unknown. We have revealed the first aspects of the insertion of proteins into nanodiscs by combining cell-free expression, noncovalent mass spectrometry, and NMR spectroscopy. We provide evidence of cooperative insertion of homo-oligomeric complexes and demonstrate the possibility to modulate their stoichiometry by modifying reaction conditions. Additionally, we show that significant amounts of lipid are released from the nanodiscs upon insertion of larger protein complexes.
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Affiliation(s)
- Oliver Peetz
- Institute of Physical and Theoretical Chemistry and ‡Institute of Biophysical Chemistry, Centre for Biomolecular Magnetic Resonance, J.W. Goethe-University , Frankfurt am Main 60438, Germany
| | - Erik Henrich
- Institute of Physical and Theoretical Chemistry and ‡Institute of Biophysical Chemistry, Centre for Biomolecular Magnetic Resonance, J.W. Goethe-University , Frankfurt am Main 60438, Germany
| | - Aisha Laguerre
- Institute of Physical and Theoretical Chemistry and ‡Institute of Biophysical Chemistry, Centre for Biomolecular Magnetic Resonance, J.W. Goethe-University , Frankfurt am Main 60438, Germany
| | - Frank Löhr
- Institute of Physical and Theoretical Chemistry and ‡Institute of Biophysical Chemistry, Centre for Biomolecular Magnetic Resonance, J.W. Goethe-University , Frankfurt am Main 60438, Germany
| | - Christopher Hein
- Institute of Physical and Theoretical Chemistry and ‡Institute of Biophysical Chemistry, Centre for Biomolecular Magnetic Resonance, J.W. Goethe-University , Frankfurt am Main 60438, Germany
| | - Volker Dötsch
- Institute of Physical and Theoretical Chemistry and ‡Institute of Biophysical Chemistry, Centre for Biomolecular Magnetic Resonance, J.W. Goethe-University , Frankfurt am Main 60438, Germany
| | - Frank Bernhard
- Institute of Physical and Theoretical Chemistry and ‡Institute of Biophysical Chemistry, Centre for Biomolecular Magnetic Resonance, J.W. Goethe-University , Frankfurt am Main 60438, Germany
| | - Nina Morgner
- Institute of Physical and Theoretical Chemistry and ‡Institute of Biophysical Chemistry, Centre for Biomolecular Magnetic Resonance, J.W. Goethe-University , Frankfurt am Main 60438, Germany
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71
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Luther A, Bisang C, Obrecht D. Advances in macrocyclic peptide-based antibiotics. Bioorg Med Chem 2017; 26:2850-2858. [PMID: 28886999 DOI: 10.1016/j.bmc.2017.08.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 07/14/2017] [Accepted: 08/06/2017] [Indexed: 11/30/2022]
Abstract
Macrocyclic peptide-based natural products have provided powerful new antibiotic drugs, drug candidates, and scaffolds for medicinal chemists as a source of inspiration to design novel antibiotics. While most of those natural products are active mainly against Gram-positive pathogens, novel macrocyclic peptide-based compounds have recently been described, which exhibit potent and specific activity against some of the most problematic Gram-negative ESKAPE pathogens. This mini-review gives an up-date on recent developments.
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Affiliation(s)
- Anatol Luther
- Polyphor Ltd, Hegenheimermattweg 125, CH-4123 Allschwil, Switzerland.
| | - Christian Bisang
- Polyphor Ltd, Hegenheimermattweg 125, CH-4123 Allschwil, Switzerland
| | - Daniel Obrecht
- Polyphor Ltd, Hegenheimermattweg 125, CH-4123 Allschwil, Switzerland.
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72
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Computational studies of membrane proteins: from sequence to structure to simulation. Curr Opin Struct Biol 2017; 45:133-141. [DOI: 10.1016/j.sbi.2017.04.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 04/07/2017] [Accepted: 04/07/2017] [Indexed: 11/19/2022]
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73
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Non-invasive 3D and 360° optical imaging of micro-particles. Sci Rep 2017; 7:6384. [PMID: 28743995 PMCID: PMC5527111 DOI: 10.1038/s41598-017-06830-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 06/19/2017] [Indexed: 11/11/2022] Open
Abstract
Scanning electron microscopy and X-ray microtomography are useful methods for high resolution shape imaging. Visible microscopy is also common, however, developing a low-cost and customizable system for surface and shape investigation of optically active particles is challenging. In this work, we demonstrate an assembly offering good light sensitivity, flexibility of illumination and contrasts from varying angles. The design was applied, together with recent programs for focus-stacking, to analyze crystals of taurine, L-glutamic acid, acetylsalicylic acid, and copper sulfate, along with digital 3D-360° modelling of phosphorescent [Ru(bpy)3]Cl2 and strontium aluminate particles. We further tested the approach for real time monitoring of size, shape and texture analysis of fat filled milk particles and acid whey powders. The findings show proof of concept for detailed feature imaging of particles directly from the process environment.
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74
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Structural insights into lipoprotein N-acylation by Escherichia coli apolipoprotein N-acyltransferase. Proc Natl Acad Sci U S A 2017; 114:E6044-E6053. [PMID: 28698362 DOI: 10.1073/pnas.1707813114] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Gram-negative bacteria express a diverse array of lipoproteins that are essential for various aspects of cell growth and virulence, including nutrient uptake, signal transduction, adhesion, conjugation, sporulation, and outer membrane protein folding. Lipoprotein maturation requires the sequential activity of three enzymes that are embedded in the cytoplasmic membrane. First, phosphatidylglycerol:prolipoprotein diacylglyceryl transferase (Lgt) recognizes a conserved lipobox motif within the prolipoprotein signal sequence and catalyzes the addition of diacylglycerol to an invariant cysteine. The signal sequence is then cleaved by signal peptidase II (LspA) to give an N-terminal S-diacylglyceryl cysteine. Finally, apolipoprotein N-acyltransferase (Lnt) catalyzes the transfer of the sn-1-acyl chain of phosphatidylethanolamine to this N-terminal cysteine, generating a mature, triacylated lipoprotein. Although structural studies of Lgt and LspA have yielded significant mechanistic insights into this essential biosynthetic pathway, the structure of Lnt has remained elusive. Here, we present crystal structures of wild-type and an active-site mutant of Escherichia coli Lnt. The structures reveal a monomeric eight-transmembrane helix fold that supports a periplasmic carbon-nitrogen hydrolase domain containing a Cys-Glu-Lys catalytic triad. Two lipids are bound at the active site in the structures, and we propose a putative phosphate recognition site where a chloride ion is coordinated near the active site. Based on these structures and complementary cell-based, biochemical, and molecular dynamics approaches, we propose a mechanism for substrate engagement and catalysis by E. coli Lnt.
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75
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Lu G, Xu Y, Zhang K, Xiong Y, Li H, Cui L, Wang X, Lou J, Zhai Y, Sun F, Zhang XC. Crystal structure of E. coli apolipoprotein N-acyl transferase. Nat Commun 2017; 8:15948. [PMID: 28885614 PMCID: PMC5500890 DOI: 10.1038/ncomms15948] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 05/13/2017] [Indexed: 11/09/2022] Open
Abstract
In Gram-negative bacteria, lipid modification of proteins is catalysed in a three-step pathway. Apolipoprotein N-acyl transferase (Lnt) catalyses the third step in this pathway, whereby it transfers an acyl chain from a phospholipid to the amine group of the N-terminal cysteine residue of the apolipoprotein. Here, we report the 2.6-Å crystal structure of Escherichia coli Lnt. This enzyme contains an exo-membrane nitrilase domain fused to a transmembrane (TM) domain. The TM domain of Lnt contains eight TM helices which form a membrane-embedded cavity with a lateral opening and a periplasmic exit. The nitrilase domain is located on the periplasmic side of the membrane, with its catalytic cavity connected to the periplasmic exit of the TM domain. An amphipathic lid loop from the nitrilase domain interacts with the periplasmic lipid leaflet, forming an interfacial entrance from the lipid bilayer to the catalytic centre for both the lipid donor and acceptor substrates.
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Affiliation(s)
- Guangyuan Lu
- National Laboratory of Macromolecules, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China.,School of Life Sciences, University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049, China
| | - Yingzhi Xu
- National Laboratory of Macromolecules, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
| | - Kai Zhang
- National Laboratory of Macromolecules, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
| | - Yong Xiong
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06411, USA
| | - He Li
- National Laboratory of Macromolecules, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
| | - Lei Cui
- National Laboratory of Macromolecules, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
| | - Xianping Wang
- National Laboratory of Macromolecules, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China.,School of Life Sciences, University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049, China
| | - Jizhong Lou
- National Laboratory of Macromolecules, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China.,School of Life Sciences, University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049, China
| | - Yujia Zhai
- National Laboratory of Macromolecules, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
| | - Fei Sun
- National Laboratory of Macromolecules, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China.,School of Life Sciences, University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049, China
| | - Xuejun C Zhang
- National Laboratory of Macromolecules, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China.,School of Life Sciences, University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049, China
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76
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Structural insights into the mechanism of the membrane integral N-acyltransferase step in bacterial lipoprotein synthesis. Nat Commun 2017; 8:15952. [PMID: 28675161 PMCID: PMC5500888 DOI: 10.1038/ncomms15952] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 05/13/2017] [Indexed: 02/07/2023] Open
Abstract
Lipoproteins serve essential roles in the bacterial cell envelope. The posttranslational modification pathway leading to lipoprotein synthesis involves three enzymes. All are potential targets for the development of new antibiotics. Here we report the crystal structure of the last enzyme in the pathway, apolipoprotein N-acyltransferase, Lnt, responsible for adding a third acyl chain to the lipoprotein’s invariant diacylated N-terminal cysteine. Structures of Lnt from Pseudomonas aeruginosa and Escherichia coli have been solved; they are remarkably similar. Both consist of a membrane domain on which sits a globular periplasmic domain. The active site resides above the membrane interface where the domains meet facing into the periplasm. The structures are consistent with the proposed ping-pong reaction mechanism and suggest plausible routes by which substrates and products enter and leave the active site. While Lnt may present challenges for antibiotic development, the structures described should facilitate design of therapeutics with reduced off-target effects. Lipoproteins are essential components of bacterial membranes. Here the authors present the crystal structures of Pseudomonas aeruginosa and Escherichia coli apolipoprotein N-acyltransferase, which catalyses the final step in the lipoprotein synthesis pathway, and give insights into its mechanism.
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77
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Stringency of bacterial prolipoprotein signal peptidase (LspA) in recognition of signal peptides - Structure-function correlation. Biochem Biophys Res Commun 2017; 488:413-417. [PMID: 28506828 DOI: 10.1016/j.bbrc.2017.05.069] [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: 05/01/2017] [Accepted: 05/11/2017] [Indexed: 11/22/2022]
Abstract
Bacterial lipid modification of proteins is an essential post-translational event committed by Phosphatidylglycerol: prolipoprotein diacylglyceryl transferase (Lgt) by catalysing diacyglyceryl transfer from Phosphatidylglycerol to cysteine present in the characteristic 'lipobox' ([LVI] (-3) [ASTVI] (-2) [GAS] (-1) C (+1)) of prolipoprotein signal peptides. This is then followed by the cleavage of the signal peptide by lipoprotein-specific signal peptidase (LspA). It had been known for long that threonine at the -1 position allows diacylglyceryl modification by Lgt, but not signal peptide cleavage by LspA. We have addressed this unexplained stringency by computational analysis of the recently published 3D structure of LspA with its competitive inhibitor as well as transition state analogue, globomycin using PyMoL viewing tool and VADAR (Volume, Area, Dihedral Angle Reporter) web server. The propensity to form hydrogen bond (2.9a) between the hydroxyl group of threonine (not possible with serine) and the NH of the lipid-modified cysteine, possible only in the transition state, will prevent the protonation of NH of the leaving peptide and therefore its cleavage. This knowledge could be useful for designing inhibitors of this essential pathway in bacteria or for engineering LspA.
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78
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Redefining the essential trafficking pathway for outer membrane lipoproteins. Proc Natl Acad Sci U S A 2017; 114:4769-4774. [PMID: 28416660 DOI: 10.1073/pnas.1702248114] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The outer membrane (OM) of Gram-negative bacteria is a permeability barrier and an intrinsic antibiotic resistance factor. Lipoproteins are OM components that function in cell wall synthesis, diverse secretion systems, and antibiotic efflux pumps. Moreover, each of the essential OM machines that assemble the barrier requires one or more lipoproteins. This dependence is thought to explain the essentiality of the periplasmic chaperone LolA and its OM receptor LolB that traffic lipoproteins to the OM. However, we show that in strains lacking substrates that are toxic when mislocalized, both LolA and LolB can be completely bypassed by activating an envelope stress response without compromising trafficking of essential lipoproteins. We identify the Cpx stress response as a monitor of lipoprotein trafficking tasked with protecting the cell from mislocalized lipoproteins. Moreover, our findings reveal that an alternate trafficking pathway exists that can, under certain conditions, bypass the functions of LolA and LolB, implying that these proteins do not perform any truly essential mechanistic steps in lipoprotein trafficking. Instead, these proteins' key function is to prevent lethal accumulation of mislocalized lipoproteins.
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79
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Zeng X, Wu P, Yao C, Liang J, Zhang S, Yin H. Small Molecule and Peptide Recognition of Protein Transmembrane Domains. Biochemistry 2017; 56:2076-2085. [DOI: 10.1021/acs.biochem.6b00909] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Xianfeng Zeng
- Center
of Basic Molecular Science, Department of Chemistry, Tsinghua University, Beijing 100082, China
| | - Peiyao Wu
- Center
of Basic Molecular Science, Department of Chemistry, Tsinghua University, Beijing 100082, China
| | - Chengbo Yao
- Center
of Basic Molecular Science, Department of Chemistry, Tsinghua University, Beijing 100082, China
| | - Jiaqi Liang
- Center
of Basic Molecular Science, Department of Chemistry, Tsinghua University, Beijing 100082, China
| | - Shuting Zhang
- Center
of Basic Molecular Science, Department of Chemistry, Tsinghua University, Beijing 100082, China
- School
of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang 453007, China
| | - Hang Yin
- Center
of Basic Molecular Science, Department of Chemistry, Tsinghua University, Beijing 100082, China
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80
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Biotechnology approaches to produce potent, self-adjuvanting antigen-adjuvant fusion protein subunit vaccines. Biotechnol Adv 2017; 35:375-389. [PMID: 28288861 DOI: 10.1016/j.biotechadv.2017.03.005] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2017] [Revised: 03/08/2017] [Accepted: 03/08/2017] [Indexed: 01/07/2023]
Abstract
Traditional vaccination approaches (e.g. live attenuated or killed microorganisms) are among the most effective means to prevent the spread of infectious diseases. These approaches, nevertheless, have failed to yield successful vaccines against many important pathogens. To overcome this problem, methods have been developed to identify microbial components, against which protective immune responses can be elicited. Subunit antigens identified by these approaches enable the production of defined vaccines, with improved safety profiles. However, they are generally poorly immunogenic, necessitating their administration with potent immunostimulatory adjuvants. Since few safe and effective adjuvants are currently used in vaccines approved for human use, with those available displaying poor potency, or an inability to stimulate the types of immune responses required for vaccines against specific diseases (e.g. cytotoxic lymphocytes (CTLs) to treat cancers), the development of new vaccines will be aided by the availability of characterized platforms of new adjuvants, improving our capacity to rationally select adjuvants for different applications. One such approach, involves the addition of microbial components (pathogen-associated molecular patterns; PAMPs), that can stimulate strong immune responses, into subunit vaccine formulations. The conjugation of PAMPs to subunit antigens provides a means to greatly increase vaccine potency, by targeting immunostimulation and antigen to the same antigen presenting cell. Thus, methods that enable the efficient, and inexpensive production of antigen-adjuvant fusions represent an exciting mean to improve immunity towards subunit antigens. Herein we review four protein-based adjuvants (flagellin, bacterial lipoproteins, the extra domain A of fibronectin (EDA), and heat shock proteins (Hsps)), which can be genetically fused to antigens to enable recombinant production of antigen-adjuvant fusion proteins, with a focus on their mechanisms of action, structural or sequence requirements for activity, sequence modifications to enhance their activity or simplify production, adverse effects, and examples of vaccines in preclinical or human clinical trials.
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81
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Ovchinnikov S, Park H, Varghese N, Huang PS, Pavlopoulos GA, Kim DE, Kamisetty H, Kyrpides NC, Baker D. Protein structure determination using metagenome sequence data. Science 2017; 355:294-298. [PMID: 28104891 PMCID: PMC5493203 DOI: 10.1126/science.aah4043] [Citation(s) in RCA: 336] [Impact Index Per Article: 48.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 11/22/2016] [Indexed: 01/30/2023]
Abstract
Despite decades of work by structural biologists, there are still ~5200 protein families with unknown structure outside the range of comparative modeling. We show that Rosetta structure prediction guided by residue-residue contacts inferred from evolutionary information can accurately model proteins that belong to large families and that metagenome sequence data more than triple the number of protein families with sufficient sequences for accurate modeling. We then integrate metagenome data, contact-based structure matching, and Rosetta structure calculations to generate models for 614 protein families with currently unknown structures; 206 are membrane proteins and 137 have folds not represented in the Protein Data Bank. This approach provides the representative models for large protein families originally envisioned as the goal of the Protein Structure Initiative at a fraction of the cost.
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Affiliation(s)
- Sergey Ovchinnikov
- Department of Biochemistry, University of Washington, Seattle, WA 98105, USA
- Institute for Protein Design, University of Washington, Seattle, WA 98105, USA
- Molecular and Cellular Biology Program, University of Washington, Seattle, WA 98195, USA
| | - Hahnbeom Park
- Department of Biochemistry, University of Washington, Seattle, WA 98105, USA
- Institute for Protein Design, University of Washington, Seattle, WA 98105, USA
| | | | - Po-Ssu Huang
- Department of Biochemistry, University of Washington, Seattle, WA 98105, USA
- Institute for Protein Design, University of Washington, Seattle, WA 98105, USA
| | | | - David E Kim
- Department of Biochemistry, University of Washington, Seattle, WA 98105, USA
- Howard Hughes Medical Institute, University of Washington, Box 357370, Seattle, WA 98105, USA
| | | | - Nikos C Kyrpides
- Joint Genome Institute, Walnut Creek, CA 94598, USA
- Department of Biological Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | - David Baker
- Department of Biochemistry, University of Washington, Seattle, WA 98105, USA.
- Institute for Protein Design, University of Washington, Seattle, WA 98105, USA
- Howard Hughes Medical Institute, University of Washington, Box 357370, Seattle, WA 98105, USA
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82
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Henrich E, Peetz O, Hein C, Laguerre A, Hoffmann B, Hoffmann J, Dötsch V, Bernhard F, Morgner N. Analyzing native membrane protein assembly in nanodiscs by combined non-covalent mass spectrometry and synthetic biology. eLife 2017; 6. [PMID: 28067619 PMCID: PMC5291076 DOI: 10.7554/elife.20954] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 01/04/2017] [Indexed: 01/01/2023] Open
Abstract
Membrane proteins frequently assemble into higher order homo- or hetero-oligomers within their natural lipid environment. This complex formation can modulate their folding, activity as well as substrate selectivity. Non-disruptive methods avoiding critical steps, such as membrane disintegration, transfer into artificial environments or chemical modifications are therefore essential to analyze molecular mechanisms of native membrane protein assemblies. The combination of cell-free synthetic biology, nanodisc-technology and non-covalent mass spectrometry provides excellent synergies for the analysis of membrane protein oligomerization within defined membranes. We exemplify our strategy by oligomeric state characterization of various membrane proteins including ion channels, transporters and membrane-integrated enzymes assembling up to hexameric complexes. We further indicate a lipid-dependent dimer formation of MraY translocase correlating with the enzymatic activity. The detergent-free synthesis of membrane protein/nanodisc samples and the analysis by LILBID mass spectrometry provide a versatile platform for the analysis of membrane proteins in a native environment.
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Affiliation(s)
- Erik Henrich
- Institute of Biophysical Chemistry, Centre for Biomolecular Magnetic Resonance, J W Goethe-University, Frankfurt am Main, Germany
| | - Oliver Peetz
- Institute of Physical and Theoretical Chemistry, J W Goethe-University, Frankfurt am Main, Germany
| | - Christopher Hein
- Institute of Biophysical Chemistry, Centre for Biomolecular Magnetic Resonance, J W Goethe-University, Frankfurt am Main, Germany
| | - Aisha Laguerre
- Institute of Biophysical Chemistry, Centre for Biomolecular Magnetic Resonance, J W Goethe-University, Frankfurt am Main, Germany
| | - Beate Hoffmann
- Institute of Biophysical Chemistry, Centre for Biomolecular Magnetic Resonance, J W Goethe-University, Frankfurt am Main, Germany
| | - Jan Hoffmann
- Institute of Physical and Theoretical Chemistry, J W Goethe-University, Frankfurt am Main, Germany
| | - Volker Dötsch
- Institute of Biophysical Chemistry, Centre for Biomolecular Magnetic Resonance, J W Goethe-University, Frankfurt am Main, Germany
| | - Frank Bernhard
- Institute of Biophysical Chemistry, Centre for Biomolecular Magnetic Resonance, J W Goethe-University, Frankfurt am Main, Germany
| | - Nina Morgner
- Institute of Physical and Theoretical Chemistry, J W Goethe-University, Frankfurt am Main, Germany
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83
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Antibacterial New Target Discovery: Sentinel Examples, Strategies, and Surveying Success. TOPICS IN MEDICINAL CHEMISTRY 2017. [DOI: 10.1007/7355_2016_31] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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84
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Abstract
Lipoproteins are lipid-modified proteins that dominate the spirochetal proteome. While found in all bacteria, spirochetal lipoproteins have unique features and play critical roles in spirochete biology. For this reason, considerable effort has been devoted to determining how the lipoproteome is generated. Essential features of the structural elements of lipoproteins are now understood with greater clarity, enabling greater confidence in identification of lipoproteins from genomic sequences. The journey from the ribosome to the outer membrane, and in some cases, to the cellular surface has been defined, including secretion, lipidation, sorting, and export across the outer membrane. Given their abundance and importance, it is not surprising that spirochetes have developed a number of strategies for regulating the spatiotemporal expression of lipoproteins. In some cases, lipoprotein expression is tied to various environmental cues, while in other cases, it is linked to growth rate. This regulation enables spirochetes to express certain lipoproteins at high levels in one phase of the spirochete lifecycle, while dramatically downregulating the same lipoproteins in other phases. The mammalian host has developed specialized mechanisms for recognizing lipoproteins and triggering an immune response. Evasion of that immune response is essential for spirochete persistence. For this reason, spirochetes have developed mechanisms for altering lipoproteins. Lipoproteins recognized by antibodies formed during infection are key serodiagnostic antigens. In addition, lipoprotein vaccines have been developed for generating an immune response to control or prevent a spirochete infection. This chapter summarizes our current understanding of lipoproteins in interactions of spirochetes with their hosts.
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85
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Herrmann J, Fayad AA, Müller R. Natural products from myxobacteria: novel metabolites and bioactivities. Nat Prod Rep 2016; 34:135-160. [PMID: 27907217 DOI: 10.1039/c6np00106h] [Citation(s) in RCA: 152] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Covering: 2011-July 2016Myxobacteria are a rich source for structurally diverse secondary metabolites with intriguing biological activities. Here we report on new natural products that were isolated from myxobacteria in the period of 2011 to July 2016. Some examples of recent advances on modes-of-action are also summarised along with a more detailed overview on five compound classes currently assessed in preclinical studies.
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Affiliation(s)
- J Herrmann
- Helmholtz Institute for Pharmaceutical Research Saarland, Department of Microbial Natural Products, Helmholtz Centre for Infection Research and Department of Pharmaceutical Biotechnology, Saarland University, Campus E8.1, 66123 Saarbrücken, Germany.
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86
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Culp E, Wright GD. Bacterial proteases, untapped antimicrobial drug targets. J Antibiot (Tokyo) 2016; 70:366-377. [PMID: 27899793 DOI: 10.1038/ja.2016.138] [Citation(s) in RCA: 145] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 09/29/2016] [Accepted: 10/06/2016] [Indexed: 01/05/2023]
Abstract
Bacterial proteases are an extensive collection of enzymes that have vital roles in cell viability, stress response and pathogenicity. Although their perturbation clearly offers the potential for antimicrobial drug development, both as traditional antibiotics and anti-virulence drugs, they are not yet the target of any clinically used therapeutics. Here we describe the potential for and recent progress in the development of compounds targeting bacterial proteases with a focus on AAA+ family proteolytic complexes and signal peptidases (SPs). Caseinolytic protease (ClpP) belongs to the AAA+ family of proteases, a group of multimeric barrel-shaped complexes whose activity is tightly regulated by associated AAA+ ATPases. The opportunity for chemical perturbation of these complexes is demonstrated by compounds targeting ClpP for inhibition, activation or perturbation of its associated ATPase. Meanwhile, SPs are also a proven antibiotic target. Responsible for the cleavage of targeting peptides during protein secretion, both type I and type II SPs have been successfully targeted by chemical inhibitors. As the threat of pan-antibiotic resistance continues to grow, these and other bacterial proteases offer an arsenal of novel antibiotic targets ripe for development.
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Affiliation(s)
- Elizabeth Culp
- Michael G. DeGroote Institute for Infectious Disease Research and the Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Gerard D Wright
- Michael G. DeGroote Institute for Infectious Disease Research and the Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
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87
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Narita SI, Tokuda H. Bacterial lipoproteins; biogenesis, sorting and quality control. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1862:1414-1423. [PMID: 27871940 DOI: 10.1016/j.bbalip.2016.11.009] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 11/11/2016] [Accepted: 11/14/2016] [Indexed: 12/20/2022]
Abstract
Bacterial lipoproteins are a subset of membrane proteins localized on either leaflet of the lipid bilayer. These proteins are anchored to membranes through their N-terminal lipid moiety attached to a conserved Cys. Since the protein moiety of most lipoproteins is hydrophilic, they are expected to play various roles in a hydrophilic environment outside the cytoplasmic membrane. Gram-negative bacteria such as Escherichia coli possess an outer membrane, to which most lipoproteins are sorted. The Lol pathway plays a central role in the sorting of lipoproteins to the outer membrane after lipoprotein precursors are processed to mature forms in the cytoplasmic membrane. Most lipoproteins are anchored to the inner leaflet of the outer membrane with their protein moiety in the periplasm. However, recent studies indicated that some lipoproteins further undergo topology change in the outer membrane, and play critical roles in the biogenesis and quality control of the outer membrane. This article is part of a Special Issue entitled: Bacterial Lipids edited by Russell E. Bishop.
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Affiliation(s)
| | - Hajime Tokuda
- University of Morioka, Takizawa, Iwate 020-0694, Japan.
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88
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From Nanodiscs to Isotropic Bicelles: A Procedure for Solution Nuclear Magnetic Resonance Studies of Detergent-Sensitive Integral Membrane Proteins. Structure 2016; 24:1830-1841. [PMID: 27618661 DOI: 10.1016/j.str.2016.07.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Revised: 07/25/2016] [Accepted: 07/25/2016] [Indexed: 01/04/2023]
Abstract
Nanodiscs and isotropic bicelles are promising membrane mimetics in the field of solution nuclear magnetic resonance (NMR) spectroscopy of integral membrane proteins (IMPs). Despite varied challenges to solution NMR studies of IMPs, we attribute the paucity of solution NMR structures in these environments to the inability of diverse IMPs to withstand detergent treatment during standard nanodisc and bicelle preparations. Here, we present a strategy that creates small isotropic bicelles from IMPs co-translationally embedded in large nanodiscs using cell-free expression. Our results demonstrate appreciable gains in NMR spectral quality while preserving lipid-IMP contacts. We validate the approach on the detergent-sensitive LspA, which finally allowed us to perform high-quality triple-resonance NMR experiments for structural studies. Our strategy of producing bicelles from nanodiscs comprehensively avoids detergent during expression and preparation and is suitable for solution NMR spectroscopy of lipid-IMP complexes.
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89
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Szewczyk J, Collet JF. The Journey of Lipoproteins Through the Cell: One Birthplace, Multiple Destinations. Adv Microb Physiol 2016; 69:1-50. [PMID: 27720009 DOI: 10.1016/bs.ampbs.2016.07.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Bacterial lipoproteins are a very diverse group of proteins characterized by the presence of an N-terminal lipid moiety that serves as a membrane anchor. Lipoproteins have a wide variety of crucial functions, ranging from envelope biogenesis to stress response. In Gram-negative bacteria, lipoproteins can be targeted to various destinations in the cell, including the periplasmic side of the cytoplasmic or outer membrane, the cell surface or the external milieu. The sorting mechanisms have been studied in detail in Escherichia coli, but exceptions to the rules established in this model bacterium exist in other bacteria. In this chapter, we will present the current knowledge on lipoprotein sorting in the cell. Our particular focus will be on the surface-exposed lipoproteins that appear to be much more common than previously assumed. We will discuss the different targeting strategies, provide numerous examples of surface-exposed lipoproteins and discuss the techniques used to assess their surface exposure.
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Affiliation(s)
- J Szewczyk
- WELBIO, Brussels, Belgium; de Duve Institute, Université catholique de Louvain, Brussels, Belgium
| | - J-F Collet
- WELBIO, Brussels, Belgium; de Duve Institute, Université catholique de Louvain, Brussels, Belgium.
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90
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Becker K, Sander P. Mycobacterium tuberculosis lipoproteins in virulence and immunity - fighting with a double-edged sword. FEBS Lett 2016; 590:3800-3819. [PMID: 27350117 DOI: 10.1002/1873-3468.12273] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 06/06/2016] [Accepted: 06/26/2016] [Indexed: 02/06/2023]
Abstract
Bacterial lipoproteins are secreted membrane-anchored proteins characterized by a lipobox motif. This lipobox motif directs post-translational modifications at the conserved cysteine through the consecutive action of three enzymes: Lgt, LspA and Lnt, which results in di- or triacylated forms. Lipoproteins are abundant in all bacteria including Mycobacterium tuberculosis and often involved in virulence and immunoregulatory processes. On the one hand, disruption of the biosynthesis pathway of lipoproteins leads to attenuation of M. tuberculosis in vivo, and mycobacteria deficient for certain lipoproteins have been assessed as attenuated live vaccine candidates. On the other hand, several mycobacterial lipoproteins form immunodominant antigens which promote an immune response. Some of these have been explored in DNA or subunit vaccination approaches against tuberculosis. The immune recognition of specific lipoproteins, however, might also benefit long-term survival of M. tuberculosis through immune modulation, while others induce protective responses. Exploiting lipoproteins as vaccines is thus a complex matter which requires deliberative investigation. The dual role of lipoproteins in the immunity to and pathogenicity of mycobacteria is discussed here.
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Affiliation(s)
- Katja Becker
- Institute of Medical Microbiology, University of Zurich, Switzerland
| | - Peter Sander
- Institute of Medical Microbiology, University of Zurich, Switzerland
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