1
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Dhar R, Bowman AM, Hatungimana B, Sg Slusky J. Evolutionary Engineering a Larger Porin Using a Loop-to-Hairpin Mechanism. J Mol Biol 2023; 435:168292. [PMID: 37769963 PMCID: PMC11215794 DOI: 10.1016/j.jmb.2023.168292] [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: 06/14/2023] [Revised: 09/20/2023] [Accepted: 09/21/2023] [Indexed: 10/03/2023]
Abstract
In protein evolution, diversification is generally driven by genetic duplication. The hallmarks of this mechanism are visible in the repeating topology of various proteins. In outer membrane β-barrels, duplication is visible with β-hairpins as the repeating unit of the barrel. In contrast to the overall use of duplication in diversification, a computational study hypothesized evolutionary mechanisms other than hairpin duplications leading to increases in the number of strands in outer membrane β-barrels. Specifically, the topology of some 16- and 18-stranded β-barrels appear to have evolved through a loop to β-hairpin transition. Here we test this novel evolutionary mechanism by creating a chimeric protein from an 18-stranded β-barrel and an evolutionarily related 16-stranded β-barrel. The chimeric combination of the two was created by replacing loop L3 of the 16-stranded barrel with the sequentially matched transmembrane β-hairpin region of the 18-stranded barrel. We find the resulting chimeric protein is stable and has characteristics of increased strand number. This study provides the first experimental evidence supporting the evolution through a loop to β-hairpin transition.
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Affiliation(s)
- Rik Dhar
- Department of Molecular Biosciences, The University of Kansas, Lawrence, KS 66045, USA. https://twitter.com/Rik_Skywalker
| | - Alexander M Bowman
- Department of Molecular Biosciences, The University of Kansas, Lawrence, KS 66045, USA
| | - Brunojoel Hatungimana
- Department of Molecular Biosciences, The University of Kansas, Lawrence, KS 66045, USA
| | - Joanna Sg Slusky
- Department of Molecular Biosciences, The University of Kansas, Lawrence, KS 66045, USA; Computational Biology Program, The University of Kansas, Lawrence, KS 66047, USA.
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2
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Chen C, Song M, Li K, Yan S, Chen M, Geng J. E. coli outer membrane protein T (OmpT) nanopore for peptide sensing. Biochem Biophys Res Commun 2023; 677:132-140. [PMID: 37586211 DOI: 10.1016/j.bbrc.2023.05.125] [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: 04/24/2023] [Accepted: 05/31/2023] [Indexed: 08/18/2023]
Abstract
Peptide detection methods with facility and high sensitivity are essential for diagnosing disease associated with peptide biomarkers. Nanopore sensing technology had emerged as a low cost, high-throughput, and scalable tool for peptide detection. The omptins family proteins which can form β-barrel pores have great potentials to be developed as nanopore biosensor. However, there are no study about the channel properties of E. coli OmpT and the development of OmpT as a nanopore biosensor. In this study, the OmpT biological nanopore channel was constructed with a conductance of 1.49 nS in 500 mM NaCl buffer and a three-step gating phenomenon under negative voltage higher than 100 mV and then was developed as a peptide biosensor which can detect peptide without the interfere of ssDNA and dNTPs. The OmpT constructed in this study has potential application in peptide detection, and also provides a new idea for the detection of peptides using the specific binding ability of protease.
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Affiliation(s)
- Chuan Chen
- Department of Laboratory Medicine, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center, Chengdu, 610041, China; School of Pharmacy, North Sichuan Medical College, Nanchong, 637000, China
| | - Mengxiao Song
- Department of Laboratory Medicine, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center, Chengdu, 610041, China
| | - Kaiju Li
- Department of Laboratory Medicine, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center, Chengdu, 610041, China
| | - Shixin Yan
- Department of Laboratory Medicine, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center, Chengdu, 610041, China
| | - Mutian Chen
- Department of Laboratory Medicine, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center, Chengdu, 610041, China
| | - Jia Geng
- Department of Laboratory Medicine, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center, Chengdu, 610041, China; Tianfu Jincheng Laboratory, City of Future Medicine, Chengdu 641400, China.
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3
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Dhar R, Bowman AM, Hatungimana B, Slusky JS. Evolutionary engineering a larger porin using a loop-to-hairpin mechanism. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.14.544993. [PMID: 37398247 PMCID: PMC10312768 DOI: 10.1101/2023.06.14.544993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
In protein evolution, diversification is generally driven by genetic duplication. The hallmarks of this mechanism are visible in the repeating topology of various proteins. In outer membrane β-barrels, duplication is visible with β-hairpins as the repeating unit of the barrel. In contrast to the overall use of duplication in diversification, a computational study hypothesized evolutionary mechanisms other than hairpin duplications leading to increases in the number of strands in outer membrane β-barrels. Specifically, the topology of some 16- and 18-stranded β-barrels appear to have evolved through a loop to β-hairpin transition. Here we test this novel evolutionary mechanism by creating a chimeric protein from an 18-stranded β-barrel and an evolutionarily related 16-stranded β-barrel. The chimeric combination of the two was created by replacing loop L3 of the 16-stranded barrel with the sequentially matched transmembrane β-hairpin region of the 18-stranded barrel. We find the resulting chimeric protein is stable and has characteristics of increased strand number. This study provides the first experimental evidence supporting the evolution through a loop to β-hairpin transition. Highlights We find evidence supporting a novel diversification mechanism in membrane β-barrelsThe mechanism is the conversion of an extracellular loop to transmembrane β-hairpinA chimeric protein modeling this mechanism folds stably in the membraneThe chimera has more β-structure and a larger pore, consistent with a loop-to-hairpin transition.
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Affiliation(s)
- Rik Dhar
- Department of Molecular Biosciences, The University of Kansas, Lawrence KS 66045
| | - Alexander M Bowman
- Department of Molecular Biosciences, The University of Kansas, Lawrence KS 66045
| | | | - Joanna Sg Slusky
- Department of Molecular Biosciences, The University of Kansas, Lawrence KS 66045
- Computational Biology Program, The University of Kansas, Lawrence KS 66047
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4
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Rath P, Hermann A, Schaefer R, Agustoni E, Vonach JM, Siegrist M, Miscenic C, Tschumi A, Roth D, Bieniossek C, Hiller S. High-throughput screening of BAM inhibitors in native membrane environment. Nat Commun 2023; 14:5648. [PMID: 37704632 PMCID: PMC10499997 DOI: 10.1038/s41467-023-41445-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Accepted: 09/02/2023] [Indexed: 09/15/2023] Open
Abstract
The outer membrane insertase of Gram-negative bacteria, BAM, is a key target for urgently needed novel antibiotics. Functional reconstitutions of BAM have so far been limited to synthetic membranes and with low throughput capacity for inhibitor screening. Here, we describe a BAM functional assay in native membrane environment capable of high-throughput screening. This is achieved by employing outer membrane vesicles (OMVs) to present BAM directly in native membranes. Refolding of the model substrate OmpT by BAM was possible from the chaperones SurA and Skp, with the required SurA concentration three times higher than Skp. In the OMVs, the antibiotic darobactin had a tenfold higher potency than in synthetic membranes, highlighting the need for native conditions in antibiotics development. The assay is successfully miniaturized for 1536-well plates and upscaled using large scale fermentation, resulting in high-throughput capacities to screen large commercial compound libraries. Our OMV-based assay thus lays the basis for discovery, hit validation and lead expansion of antibiotics targeting BAM.
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Affiliation(s)
- Parthasarathi Rath
- Biozentrum, University of Basel, Spitalstrasse 41, 4056, Basel, Switzerland
| | - Adrian Hermann
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Grenzacherstrasse 124, 4070, Basel, Switzerland
| | - Ramona Schaefer
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Grenzacherstrasse 124, 4070, Basel, Switzerland
| | - Elia Agustoni
- Biozentrum, University of Basel, Spitalstrasse 41, 4056, Basel, Switzerland
| | - Jean-Marie Vonach
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Grenzacherstrasse 124, 4070, Basel, Switzerland
| | - Martin Siegrist
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Grenzacherstrasse 124, 4070, Basel, Switzerland
| | - Christian Miscenic
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Grenzacherstrasse 124, 4070, Basel, Switzerland
| | - Andreas Tschumi
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Grenzacherstrasse 124, 4070, Basel, Switzerland
| | - Doris Roth
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Grenzacherstrasse 124, 4070, Basel, Switzerland
| | - Christoph Bieniossek
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Grenzacherstrasse 124, 4070, Basel, Switzerland.
| | - Sebastian Hiller
- Biozentrum, University of Basel, Spitalstrasse 41, 4056, Basel, Switzerland.
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5
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Maricar S, Gudlur S, Miserez A. Phase-Separating Peptides Recruiting Aggregation-Induced Emission Fluorogen for Rapid E. coli Detection. Anal Chem 2023. [PMID: 37327402 DOI: 10.1021/acs.analchem.3c01046] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Rationally designed biomolecular condensates have found applications primarily as drug-delivery systems, thanks to their ability to self-assemble under physico-chemical triggers (such as temperature, pH, or ionic strength) and to concomitantly trap client molecules with exceptionally high efficiency (>99%). However, their potential in (bio)sensing applications remains unexplored. Here, we describe a simple and rapid assay to detect E. coli by combining phase-separating peptide condensates containing a protease recognition site, within which an aggregation-induced emission (AIE)-fluorogen is recruited. The recruited AIE-fluorogen's fluorescence is easily detected with the naked eye when the samples are viewed under UV-A light. In the presence of E. coli, the bacteria's outer membrane protease (OmpT) cleaves the phase-separating peptides at the encoded protease recognition site, resulting in two shorter peptide fragments incapable of liquid-liquid phase separation. As a result, no condensates are formed and the fluorogen remains non-fluorescent. The assay feasibility was first tested with recombinant OmpT reconstituted in detergent micelles and subsequently confirmed with E. coli K-12. In its current format, the assay can detect E. coli K-12 (108 CFU) within 2 h in spiked water samples and 1-10 CFU/mL with the addition of a 6-7 h pre-culture step. In comparison, most commercially available E. coli detection kits can take anywhere from 8 to 24 h to report their results. Optimizing the peptides for OmpT's catalytic activity can significantly improve the detection limit and assay time. Besides detecting E. coli, the assay can be adapted to detect other Gram-negative bacteria as well as proteases having diagnostic relevance.
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Affiliation(s)
- Syed Maricar
- Biological and Biomimetic Material Laboratory (BBML), Center for Sustainable Materials (SusMat), School of Materials Science and Engineering, Nanyang Technological University (NTU), Singapore 637553, Singapore
| | - Sushanth Gudlur
- Biological and Biomimetic Material Laboratory (BBML), Center for Sustainable Materials (SusMat), School of Materials Science and Engineering, Nanyang Technological University (NTU), Singapore 637553, Singapore
| | - Ali Miserez
- Biological and Biomimetic Material Laboratory (BBML), Center for Sustainable Materials (SusMat), School of Materials Science and Engineering, Nanyang Technological University (NTU), Singapore 637553, Singapore
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6
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Sinsinbar G, Gudlur S, Liedberg B. Rapid Detection of Escherichia coli: Optimized Peptide-Polythiophene Interactions Help Reduce Assay Time and Improve Naked-Eye Detection. ACS APPLIED MATERIALS & INTERFACES 2022; 14:31541-31550. [PMID: 35797225 DOI: 10.1021/acsami.2c03294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Recent improvements in methods for rapid detection of microbial contamination in food and water samples have aided in the development of on-site and point-of-care testing. Early detection, made possible via on-site testing, can help limit the spread of food and waterborne illnesses. Recently, we reported a novel fluorescence-based Omptin-Polythiophene assay (the assay) to detect Escherichia coli in contaminated water samples. The assay targets OmpT─an E. coli outer membrane protease─and exploits the protease's ability to cleave at dibasic sites within a peptide. By combining a peptide substrate optimized for OmpT with a conjugated polythiophene reporter molecule whose optical properties vary upon interaction with the intact or cleaved peptide, we demonstrated the detection of 1-10 CFU/mL and 105 CFU/mL E. coli in 5.5 and 1 h, respectively. In comparison, most microbial detection methods that rely on culturing and plating techniques take anywhere between 8 and 24 h to report their results. Herein we report significant improvements in the assay which include reducing the assay time from an already short 1 h to a mere 10 min for detecting E. coli in highly contaminated samples and augmenting the assay with colorimetric sensing capability for naked eye discernment under normal visible light or under UV-A light. These improvements were made possible by characterizing the optical changes resulting from the interaction of the peptide with five carboxylate-functionalized polythiophene variants carrying different 3- side chain carboxylic acids and by identifying preferential peptide substrates via the screening of ten peptide sequence variants for OmpT activity.
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Affiliation(s)
- Gaurav Sinsinbar
- Center for Biomimetic Sensor Science, School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Drive, Singapore 637553, Singapore
| | - Sushanth Gudlur
- Center for Biomimetic Sensor Science, School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Drive, Singapore 637553, Singapore
| | - Bo Liedberg
- Center for Biomimetic Sensor Science, School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Drive, Singapore 637553, Singapore
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7
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Kum SL, Ho JCS, Parikh AN, Liedberg B. Amphiphilic Membrane Environments Regulate Enzymatic Behaviors of Salmonella Outer Membrane Protease. ACS BIO & MED CHEM AU 2022; 2:73-83. [PMID: 37102179 PMCID: PMC10114716 DOI: 10.1021/acsbiomedchemau.1c00027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
The role of an amphiphilic environment in the functional regulation of integral membrane proteins is well appreciated but how specific amphiphilic surrounding influences the conformational plasticity and function of a protein is less obvious. We focus on the Salmonella phosphoglycerate transport system (pgt)-encoded outer membrane protease E (PgtE), which plays an important role in tissue infiltration and survival of Salmonella enterica. Despite our understanding of its physiological functions, elucidation of its enzymatic behavior in response to the immediate amphiphilic surrounding is lacking. We monitor the proteolytic activity of PgtE reconstituted in Zwittergent 3-12 detergent micelles or a 1-palmitoyl-2-oleoyl-glycero-3-phosphocholine (POPC) bilayer and examine factors that influence its activity. We find, to our surprise, that PgtE, which is thought to elicit a rapid response toward various substrates, showed hysteretic enzymatic behavior, characterized by a prominent lag phase prior to achieving the exponential steady state in its detergent-stabilized form as well as in the outer membrane embedded native state in live bacteria. The lag phase was abolished under three conditions: preformation of an inactive detergent-stabilized PgtE-substrate complex without lipopolysaccharide (LPS), LPS-bound detergent-stabilized PgtE that had reached steady state velocity, or PgtE reconstituted into a POPC bilayer environment. Interestingly, detergent- and bilayer-stabilized PgtE showed comparable steady-state activity. And strikingly, lipopolysaccharide (LPS) becomes nonessential for the activation of PgtE when the protein is reconstituted in the phospholipid bilayer, contrasting a long-standing notion that LPS is required for proteases belonging to the omptin family to be proteolytically active. These findings suggest intriguing biological nuances for the proteolytic function of PgtE that were not well appreciated previously and offer new perspectives that may generally be applicable for omptins.
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Affiliation(s)
- Siau Ling Kum
- Centre
for Biomimetic Sensor Science, Nanyang Technological
University, 50 Nanyang Drive, 637553 Singapore
- School
of Materials Science and Engineering, Nanyang
Technological University, 50 Nanyang Ave, 639798 Singapore
| | - James C. S. Ho
- Centre
for Biomimetic Sensor Science, Nanyang Technological
University, 50 Nanyang Drive, 637553 Singapore
- School
of Materials Science and Engineering, Nanyang
Technological University, 50 Nanyang Ave, 639798 Singapore
| | - Atul N. Parikh
- Centre
for Biomimetic Sensor Science, Nanyang Technological
University, 50 Nanyang Drive, 637553 Singapore
- School
of Materials Science and Engineering, Nanyang
Technological University, 50 Nanyang Ave, 639798 Singapore
- Department of Chemistry and Department of
Biomedical Engineering, University of California, Davis, California 95616, United States
| | - Bo Liedberg
- Centre
for Biomimetic Sensor Science, Nanyang Technological
University, 50 Nanyang Drive, 637553 Singapore
- School
of Materials Science and Engineering, Nanyang
Technological University, 50 Nanyang Ave, 639798 Singapore
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8
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Park S, Park K, Cho H, Kwon J, Kim KS, Yang H. Wash-Free Amperometric Escherichia coli Detection via Rapid and Specific Proteolytic Cleavage by Its Outer Membrane OmpT. Anal Chem 2022; 94:4756-4762. [PMID: 35143182 DOI: 10.1021/acs.analchem.1c05299] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Various methods have been developed for the detection of Escherichia coli (E. coli); however, they are complex and time-consuming. OmpT─a cell membrane endopeptidase of E. coli─strongly embedded in the outer membrane of only E. coli, exposed to external solutions, with high proteolytic activity, could be a suitable target molecule for the rapid and straightforward detection of E. coli. Herein, a wash-free, sensitive, and selective amperometric method for E. coli detection, based on rapid and specific proteolytic cleavage by OmpT, has been reported. The method involved (i) rapid proteolytic cleavage of consecutive amino acids, after cleavage by OmpT, linked to an electrochemical species (4-aminophenol, AP), by leucine aminopeptidase (LAP, an exopeptidase), (ii) affinity binding of E. coli on an electrode, and (iii) electrochemical-enzymatic (EN) redox cycling. OmpT cleaved the intermediate peptide bond of a peptide substrate containing alanine-arginine-arginine-leucine-AP (-A-R-R-L-AP), forming R-L-AP, followed by the cleavage of two peptide bonds of R-L-AP sequentially by LAP, to liberate an electroactive AP. Affinity binding and EN redox cycling, in addition to rapid proteolytic cleavage by OmpT and LAP, enabled high electrochemical signal amplification. Two-sequential-cleavage was employed for the first time in protease-based detection. The calculated detection limit for E. coli cells in tap water (approximately 103 CFU/mL after 1 h incubation) was lower than those obtained without affinity binding and EN redox cycling. The detection method was highly selective to E. coli as OmpT is present in only E. coli. High sensitivity, selectivity, and the absence of wash steps make the developed detection method practically promising.
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Affiliation(s)
- Seonhwa Park
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Korea
| | - Kiryeon Park
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Korea
| | - Hyejin Cho
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Korea
| | - Jungwook Kwon
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Korea
| | - Kwang-Sun Kim
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Korea
| | - Haesik Yang
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Korea
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9
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Urner LH, Ariamajd A, Weikum A. Combinatorial synthesis enables scalable designer detergents for membrane protein studies. Chem Sci 2022; 13:10299-10307. [PMID: 36277644 PMCID: PMC9473536 DOI: 10.1039/d2sc03130b] [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: 06/01/2022] [Accepted: 08/17/2022] [Indexed: 11/21/2022] Open
Abstract
Non-ionic detergents with tailor-made properties are indispensable tools for today's world applications, such as cleaning, disinfection, and drug discovery. To facilitate their challenging production, herein we introduce a new detergent class, namely scalable hybrid detergents. We report a combinatorial synthesis strategy that allows us to fuse head groups of different detergents into hybrid detergents with unbeatable ease. Importantly, combinatorial synthesis also enables the choice between (i) high-throughput preparation of detergents for small scale applications and (ii) large scale preparation of individual detergents. This combinatorial synthesis strategy enables an unprecedented fine tuning of detergent properties, such as overall polarity and shape, which are determining factors in applications, such as membrane protein research. Our data show that membrane protein purification parameters, such as protein yields and activity, can be linked to overall polarity and shape. Conveniently, both parameters can be theoretically described by means of the hydrophilic–lipophilic balance (HLB) and packing parameter concepts. Both concepts are principally applicable to all non-ionic detergent classes, which facilitates the identification of widely applicable design guidelines for the predictable optimization of non-ionic detergents. Our findings permit access to a yet unexplored chemical space of the detergentome, therefore creating new possibilities for structure–property relationship studies. Seen from a broader perspective, combinatorial synthesis will facilitate the preparation of designer detergents with tailor-made properties for future applications in today's world. Combinatorial detergent synthesis permits access to an unexplored part of the detergentome and provides new directions for the preparation of custom-made detergents for future applications.![]()
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Affiliation(s)
- Leonhard H. Urner
- TU Dortmund University, Department of Chemistry and Chemical Biology, Otto-Hahn-Straße 6, 44227 Dortmund, Germany
| | - Armin Ariamajd
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, Takustraße 3, 14195 Berlin, Germany
| | - Alex Weikum
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, Takustraße 3, 14195 Berlin, Germany
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10
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Holt BA, Tuttle M, Xu Y, Su M, Røise JJ, Wang X, Murthy N, Kwong GA. Dimensionless parameter predicts bacterial prodrug success. Mol Syst Biol 2022; 18:e10495. [PMID: 35005851 PMCID: PMC8744131 DOI: 10.15252/msb.202110495] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 12/15/2021] [Accepted: 12/17/2021] [Indexed: 11/09/2022] Open
Abstract
Understanding mechanisms of antibiotic failure is foundational to combating the growing threat of multidrug-resistant bacteria. Prodrugs-which are converted into a pharmacologically active compound after administration-represent a growing class of therapeutics for treating bacterial infections but are understudied in the context of antibiotic failure. We hypothesize that strategies that rely on pathogen-specific pathways for prodrug conversion are susceptible to competing rates of prodrug activation and bacterial replication, which could lead to treatment escape and failure. Here, we construct a mathematical model of prodrug kinetics to predict rate-dependent conditions under which bacteria escape prodrug treatment. From this model, we derive a dimensionless parameter we call the Bacterial Advantage Heuristic (BAH) that predicts the transition between prodrug escape and successful treatment across a range of time scales (1-104 h), bacterial carrying capacities (5 × 104 -105 CFU/µl), and Michaelis constants (KM = 0.747-7.47 mM). To verify these predictions in vitro, we use two models of bacteria-prodrug competition: (i) an antimicrobial peptide hairpin that is enzymatically activated by bacterial surface proteases and (ii) a thiomaltose-conjugated trimethoprim that is internalized by bacterial maltodextrin transporters and hydrolyzed by free thiols. We observe that prodrug failure occurs at BAH values above the same critical threshold predicted by the model. Furthermore, we demonstrate two examples of how failing prodrugs can be rescued by decreasing the BAH below the critical threshold via (i) substrate design and (ii) nutrient control. We envision such dimensionless parameters serving as supportive pharmacokinetic quantities that guide the design and administration of prodrug therapeutics.
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Affiliation(s)
- Brandon Alexander Holt
- Wallace H. Coulter Department of Biomedical EngineeringGeorgia Tech College of Engineering and Emory School of MedicineAtlantaGAUSA
| | - McKenzie Tuttle
- Wallace H. Coulter Department of Biomedical EngineeringGeorgia Tech College of Engineering and Emory School of MedicineAtlantaGAUSA
| | - Yilin Xu
- Wallace H. Coulter Department of Biomedical EngineeringGeorgia Tech College of Engineering and Emory School of MedicineAtlantaGAUSA
| | - Melanie Su
- Wallace H. Coulter Department of Biomedical EngineeringGeorgia Tech College of Engineering and Emory School of MedicineAtlantaGAUSA
| | - Joachim J Røise
- Department of BioengineeringInnovative Genomics InstituteUniversity of CaliforniaBerkeleyCAUSA
| | - Xioajian Wang
- Institute of Advanced SynthesisSchool of Chemistry and Molecular EngineeringNanjing Tech UniversityNanjingChina
| | - Niren Murthy
- Department of BioengineeringInnovative Genomics InstituteUniversity of CaliforniaBerkeleyCAUSA
| | - Gabriel A Kwong
- Wallace H. Coulter Department of Biomedical EngineeringGeorgia Tech College of Engineering and Emory School of MedicineAtlantaGAUSA
- Parker H. Petit Institute of Bioengineering and BioscienceAtlantaGAUSA
- Institute for Electronics and NanotechnologyGeorgia TechAtlantaGAUSA
- Integrated Cancer Research CenterGeorgia TechAtlantaGAUSA
- Georgia ImmunoEngineering ConsortiumGeorgia Tech and Emory UniversityAtlantaGAUSA
- Emory School of MedicineAtlantaGAUSA
- Emory Winship Cancer InstituteAtlantaGAUSA
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11
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Zhang H, Mou J, Ding J, Qin W. Magneto-controlled potentiometric assay for E. coli based on cleavage of peptide by outer-membrane protease T. Electrochim Acta 2021. [DOI: 10.1016/j.electacta.2021.138408] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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12
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Urner LH, Goltsche K, Selent M, Liko I, Schweder M, Robinson CV, Pagel K, Haag R. Dendritic Oligoglycerol Regioisomer Mixtures and Their Utility for Membrane Protein Research. Chemistry 2021; 27:2537-2542. [PMID: 33026114 PMCID: PMC7898920 DOI: 10.1002/chem.202003991] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 10/06/2020] [Indexed: 12/14/2022]
Abstract
Dendrons are an important class of macromolecules that can be used for a broad range of applications. Recent studies have indicated that mixtures of oligoglycerol detergent (OGD) regioisomers are superior to individual regioisomers for protein extraction. The origin of this phenomenon remains puzzling. Here we discuss the synthesis and characterization of dendritic oligoglycerol regioisomer mixtures and their implementation into detergents. We provide experimental benchmarks to support quality control after synthesis and investigate the unusual utility of OGD regioisomer mixtures for extracting large protein quantities from biological membranes. We anticipate that our findings will enable the development of mixed detergent platforms in the future.
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Affiliation(s)
- Leonhard H. Urner
- Institute of Chemistry and BiochemistryFreie Universität BerlinTakustraße 314195BerlinGermany
| | - Katharina Goltsche
- Institute of Chemistry and BiochemistryFreie Universität BerlinTakustraße 314195BerlinGermany
| | - Marleen Selent
- Institute of Chemistry and BiochemistryFreie Universität BerlinTakustraße 314195BerlinGermany
| | - Idlir Liko
- Physical and Theoretical Chemistry LaboratoryUniversity of OxfordSouth Parks RoadOxfordOX1 3QZUK
| | - Marc‐Philip Schweder
- Institute of Chemistry and BiochemistryFreie Universität BerlinTakustraße 314195BerlinGermany
| | - Carol V. Robinson
- Physical and Theoretical Chemistry LaboratoryUniversity of OxfordSouth Parks RoadOxfordOX1 3QZUK
| | - Kevin Pagel
- Institute of Chemistry and BiochemistryFreie Universität BerlinTakustraße 314195BerlinGermany
| | - Rainer Haag
- Institute of Chemistry and BiochemistryFreie Universität BerlinTakustraße 314195BerlinGermany
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13
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Outer membrane protein evolution. Curr Opin Struct Biol 2021; 68:122-128. [PMID: 33493965 DOI: 10.1016/j.sbi.2021.01.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 12/16/2020] [Accepted: 01/02/2021] [Indexed: 01/31/2023]
Abstract
Outer membrane proteins have remarkably homogeneous structure. They are all up down β-barrels. Up down barrels themselves are composed of repeated sets of β-hairpins. The consistency of the usage of the β-hairpin throughout the outer membrane milieu allows for interrogation of the evolution of these repetitive structures. Here we describe recent investigations of outer membrane protein evolution and how evolutionary precepts have been used for novel outer membrane protein design.
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14
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Sinsinbar G, Gudlur S, Wood SE, Ammanath G, Yildiz HU, Alagappan P, Mrksich M, Liedberg B. Outer‐Membrane Protease (OmpT) Based
E. coli
Sensing with Anionic Polythiophene and Unlabeled Peptide Substrate. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202008444] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Gaurav Sinsinbar
- Centre for Biomimetic Sensor Science School of Materials Science Engineering Nanyang Technological University 50 Nanyang Drive Singapore 637553 Singapore
| | - Sushanth Gudlur
- Centre for Biomimetic Sensor Science School of Materials Science Engineering Nanyang Technological University 50 Nanyang Drive Singapore 637553 Singapore
| | - Sarah E. Wood
- Departments of Chemistry and Biomedical Engineering Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Gopal Ammanath
- Centre for Biomimetic Sensor Science School of Materials Science Engineering Nanyang Technological University 50 Nanyang Drive Singapore 637553 Singapore
| | - Hakan U. Yildiz
- Department of Chemistry Izmir Institute of Technology Urla 35430 Izmir Turkey
| | - Palaniappan Alagappan
- Centre for Biomimetic Sensor Science School of Materials Science Engineering Nanyang Technological University 50 Nanyang Drive Singapore 637553 Singapore
| | - Milan Mrksich
- Departments of Chemistry and Biomedical Engineering Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Bo Liedberg
- Centre for Biomimetic Sensor Science School of Materials Science Engineering Nanyang Technological University 50 Nanyang Drive Singapore 637553 Singapore
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15
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Sinsinbar G, Gudlur S, Wood SE, Ammanath G, Yildiz HU, Alagappan P, Mrksich M, Liedberg B. Outer-Membrane Protease (OmpT) Based E. coli Sensing with Anionic Polythiophene and Unlabeled Peptide Substrate. Angew Chem Int Ed Engl 2020; 59:18068-18077. [PMID: 32618102 DOI: 10.1002/anie.202008444] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Indexed: 01/07/2023]
Abstract
E. coli and Salmonella are two of the most common bacterial pathogens involved in foodborne and waterborne related deaths. Hence, it is critical to develop rapid and sensitive detection strategies for near-outbreak applications. Reported is a simple and specific assay to detect as low as 1 CFU mL-1 of E. coli in water within 6 hours by targeting the bacteria's surface protease activity. The assay relies on polythiophene acetic acid (PTAA) as an optical reporter and a short unlabeled peptide (LL37FRRV ) previously optimized as a substrate for OmpT, an outer-membrane protease on E. coli. LL37FRRV interacts with PTAA to enhance its fluorescence while also inducing the formation of a helical PTAA-LL37FRRV construct, as confirmed by circular dichroism. However, in the presence of E. coli LL37FRRV is cleaved and can no longer affect the conformations and optical properties of PTAA. This ability to distinguish between an intact and cleaved peptide was investigated in detail using LL37FRRV sequence variants.
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Affiliation(s)
- Gaurav Sinsinbar
- Centre for Biomimetic Sensor Science, School of Materials Science Engineering, Nanyang Technological University, 50 Nanyang Drive, Singapore, 637553, Singapore
| | - Sushanth Gudlur
- Centre for Biomimetic Sensor Science, School of Materials Science Engineering, Nanyang Technological University, 50 Nanyang Drive, Singapore, 637553, Singapore
| | - Sarah E Wood
- Departments of Chemistry and Biomedical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Gopal Ammanath
- Centre for Biomimetic Sensor Science, School of Materials Science Engineering, Nanyang Technological University, 50 Nanyang Drive, Singapore, 637553, Singapore
| | - Hakan U Yildiz
- Department of Chemistry, Izmir Institute of Technology, Urla, 35430, Izmir, Turkey
| | - Palaniappan Alagappan
- Centre for Biomimetic Sensor Science, School of Materials Science Engineering, Nanyang Technological University, 50 Nanyang Drive, Singapore, 637553, Singapore
| | - Milan Mrksich
- Departments of Chemistry and Biomedical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Bo Liedberg
- Centre for Biomimetic Sensor Science, School of Materials Science Engineering, Nanyang Technological University, 50 Nanyang Drive, Singapore, 637553, Singapore
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16
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Role of Lipopolysaccharide in Protecting OmpT from Autoproteolysis during In Vitro Refolding. Biomolecules 2020; 10:biom10060922. [PMID: 32570704 PMCID: PMC7356225 DOI: 10.3390/biom10060922] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 06/06/2020] [Accepted: 06/14/2020] [Indexed: 01/02/2023] Open
Abstract
Outer membrane protease (OmpT) is a 33.5 kDa aspartyl protease that cleaves at dibasic sites and is thought to function as a defense mechanism for E. coli against cationic antimicrobial peptides secreted by the host immune system. Despite carrying three dibasic sites in its own sequence, there is no report of OmpT autoproteolysis in vivo. However, recombinant OmpT expressed in vitro as inclusion bodies has been reported to undergo autoproteolysis during the refolding step, thus resulting in an inactive protease. In this study, we monitor and compare levels of in vitro autoproteolysis of folded and unfolded OmpT and examine the role of lipopolysaccharide (LPS) in autoproteolysis. SDS-PAGE data indicate that it is only the unfolded OmpT that undergoes autoproteolysis while the folded OmpT remains protected and resistant to autoproteolysis. This selective susceptibility to autoproteolysis is intriguing. Previous studies suggest that LPS, a co-factor necessary for OmpT activity, may play a protective role in preventing autoproteolysis. However, data presented here confirm that LPS plays no such protective role in the case of unfolded OmpT. Furthermore, OmpT mutants designed to prevent LPS from binding to its putative LPS-binding motif still exhibited excellent protease activity, suggesting that the putative LPS-binding motif is of less importance for OmpT's activity than previously proposed.
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17
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Urner LH, Liko I, Yen HY, Hoi KK, Bolla JR, Gault J, Almeida FG, Schweder MP, Shutin D, Ehrmann S, Haag R, Robinson CV, Pagel K. Modular detergents tailor the purification and structural analysis of membrane proteins including G-protein coupled receptors. Nat Commun 2020; 11:564. [PMID: 31992701 PMCID: PMC6987200 DOI: 10.1038/s41467-020-14424-8] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 12/19/2019] [Indexed: 01/29/2023] Open
Abstract
Detergents enable the purification of membrane proteins and are indispensable reagents in structural biology. Even though a large variety of detergents have been developed in the last century, the challenge remains to identify guidelines that allow fine-tuning of detergents for individual applications in membrane protein research. Addressing this challenge, here we introduce the family of oligoglycerol detergents (OGDs). Native mass spectrometry (MS) reveals that the modular OGD architecture offers the ability to control protein purification and to preserve interactions with native membrane lipids during purification. In addition to a broad range of bacterial membrane proteins, OGDs also enable the purification and analysis of a functional G-protein coupled receptor (GPCR). Moreover, given the modular design of these detergents, we anticipate fine-tuning of their properties for specific applications in structural biology. Seen from a broader perspective, this represents a significant advance for the investigation of membrane proteins and their interactions with lipids. Detergents are indispensable reagents in membrane protein structural biology. Here, L. H. Urner and co-workers introduce oligoglycerol detergents (OGDs) and use native mass spectrometry to show how interactions of membrane proteins with native membrane lipids can be preserved during purification.
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Affiliation(s)
- Leonhard H Urner
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, 14195, Berlin, Germany.,Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, OX1 3QZ, UK
| | - Idlir Liko
- Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, OX1 3QZ, UK.,OMass Therapeutics, The Schrödinger Building, Heatley Road, The Oxford Science Park, Oxford, OX4 4GE, UK
| | - Hsin-Yung Yen
- Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, OX1 3QZ, UK.,OMass Therapeutics, The Schrödinger Building, Heatley Road, The Oxford Science Park, Oxford, OX4 4GE, UK
| | - Kin-Kuan Hoi
- Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, OX1 3QZ, UK
| | - Jani Reddy Bolla
- Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, OX1 3QZ, UK
| | - Joseph Gault
- Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, OX1 3QZ, UK
| | - Fernando Gonçalves Almeida
- OMass Therapeutics, The Schrödinger Building, Heatley Road, The Oxford Science Park, Oxford, OX4 4GE, UK
| | - Marc-Philip Schweder
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, 14195, Berlin, Germany
| | - Denis Shutin
- Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, OX1 3QZ, UK
| | - Svenja Ehrmann
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, 14195, Berlin, Germany
| | - Rainer Haag
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, 14195, Berlin, Germany.
| | - Carol V Robinson
- Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, OX1 3QZ, UK.
| | - Kevin Pagel
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, 14195, Berlin, Germany. .,Department of Molecular Physics, Fritz Haber Institute of the Max Planck Society, 14195, Berlin, Germany.
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18
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Hu Y, Zhang L, Chen J, Yao J, Jin H, Yang P. Outer Membrane Protease OmpT-Based Strategy for Simplified Analysis of Histone Post-Translational Modifications by Mass Spectrometry. Anal Chem 2020; 92:732-739. [PMID: 31775502 DOI: 10.1021/acs.analchem.9b02766] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Histone modifications play an important role in regulating transcriptional gene expression and chromatin processes in eukaryotes. Increasing researches proved that aberrant post-translational modifications (PTMs) of histones is associated with many diseases. However, MS-based identification and quantification of histone PTMs are still challenging. Although classic chemical derivatization in conjunction with trypsin digestion is widely used for histone PTMs analysis in a bottom-up strategy, several side reactions have been observed in practice. In this work, outer membrane protease T (OmpT) was utilized as a protease for direct histone proteolysis and generated appropriate lengths of histone peptides for retention on reversed-phase chromatography. The powerful and unique tolerance of OmpT for modified lysines and arginines was demonstrated and can be quantitatively described for the first time, making it useful for detecting natural modifications. Using the optimized digestion conditions, we succeeded in identifying 121 histone marks from HEK293T cells, 42 of which were previously unreported. Additionally, histone H3 PTMs were quantitatively profiled in the KMS11 multiple myeloma cells and NSD2 selective knockout KMS11cells, revealing that NSD2 was of high specificity on H3K36 dimethylation. Histone chemical derivatizations are not required in our strategy, showing a remarkable strength over the conventional trypsin-based workflow.
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Affiliation(s)
- Yajun Hu
- Shanghai Stomatological Hospital & Institutes of Biomedical Sciences , Fudan University , Shanghai 200433 , China
| | - Lei Zhang
- Shanghai Stomatological Hospital & Institutes of Biomedical Sciences , Fudan University , Shanghai 200433 , China
| | - Jiajia Chen
- Shanghai Stomatological Hospital & Institutes of Biomedical Sciences , Fudan University , Shanghai 200433 , China
| | - Jun Yao
- Shanghai Stomatological Hospital & Institutes of Biomedical Sciences , Fudan University , Shanghai 200433 , China
| | - Hong Jin
- Shanghai Stomatological Hospital & Institutes of Biomedical Sciences , Fudan University , Shanghai 200433 , China
| | - Pengyuan Yang
- Shanghai Stomatological Hospital & Institutes of Biomedical Sciences , Fudan University , Shanghai 200433 , China.,Department of Chemistry , Fudan University , Shanghai 200032 , China
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19
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Desloges I, Taylor JA, Leclerc JM, Brannon JR, Portt A, Spencer JD, Dewar K, Marczynski GT, Manges A, Gruenheid S, Le Moual H, Thomassin JL. Identification and characterization of OmpT-like proteases in uropathogenic Escherichia coli clinical isolates. Microbiologyopen 2019; 8:e915. [PMID: 31496120 PMCID: PMC6854850 DOI: 10.1002/mbo3.915] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 07/01/2019] [Accepted: 07/06/2019] [Indexed: 01/01/2023] Open
Abstract
Bacterial colonization of the urogenital tract is limited by innate defenses, including the production of antimicrobial peptides (AMPs). Uropathogenic Escherichia coli (UPEC) resist AMP‐killing to cause a range of urinary tract infections (UTIs) including asymptomatic bacteriuria, cystitis, pyelonephritis, and sepsis. UPEC strains have high genomic diversity and encode numerous virulence factors that differentiate them from non‐UTI‐causing strains, including ompT. As OmpT homologs cleave and inactivate AMPs, we hypothesized that UPEC strains from patients with symptomatic UTIs have high OmpT protease activity. Therefore, we measured OmpT activity in 58 clinical E. coli isolates. While heterogeneous OmpT activities were observed, OmpT activity was significantly greater in UPEC strains isolated from patients with symptomatic infections. Unexpectedly, UPEC strains exhibiting the greatest protease activities harbored an additional ompT‐like gene called arlC (ompTp). The presence of two OmpT‐like proteases in some UPEC isolates led us to compare the substrate specificities of OmpT‐like proteases found in E. coli. While all three cleaved AMPs, cleavage efficiency varied on the basis of AMP size and secondary structure. Our findings suggest the presence of ArlC and OmpT in the same UPEC isolate may confer a fitness advantage by expanding the range of target substrates.
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Affiliation(s)
- Isabelle Desloges
- Department of Microbiology and Immunology, McGill University, Montreal, QC, Canada
| | - James A Taylor
- Department of Microbiology and Immunology, McGill University, Montreal, QC, Canada
| | - Jean-Mathieu Leclerc
- Department of Microbiology and Immunology, McGill University, Montreal, QC, Canada
| | - John R Brannon
- Department of Microbiology and Immunology, McGill University, Montreal, QC, Canada
| | - Andrea Portt
- Department of Microbiology and Immunology, McGill University, Montreal, QC, Canada
| | - John D Spencer
- Division of Nephrology, Nationwide Children's Hospital, Columbus, Ohio
| | - Ken Dewar
- Microbiome and Disease Tolerance Centre, McGill University, Montreal, QC, Canada.,Department of Human Genetics, McGill University, Montreal, QC, Canada
| | - Gregory T Marczynski
- Department of Microbiology and Immunology, McGill University, Montreal, QC, Canada.,Microbiome and Disease Tolerance Centre, McGill University, Montreal, QC, Canada
| | - Amee Manges
- School of Population and Public Health, University of British Columbia, Vancouver, BC, Canada
| | - Samantha Gruenheid
- Department of Microbiology and Immunology, McGill University, Montreal, QC, Canada.,Microbiome and Disease Tolerance Centre, McGill University, Montreal, QC, Canada
| | - Hervé Le Moual
- Department of Microbiology and Immunology, McGill University, Montreal, QC, Canada.,Microbiome and Disease Tolerance Centre, McGill University, Montreal, QC, Canada.,Faculty of Dentistry, McGill University, Montreal, QC, Canada
| | - Jenny-Lee Thomassin
- Department of Microbiology and Immunology, McGill University, Montreal, QC, Canada
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20
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Ricci DP, Silhavy TJ. Outer Membrane Protein Insertion by the β-barrel Assembly Machine. EcoSal Plus 2019; 8:10.1128/ecosalplus.ESP-0035-2018. [PMID: 30869065 PMCID: PMC6419762 DOI: 10.1128/ecosalplus.esp-0035-2018] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
Abstract
Like all outer membrane (OM) constituents, integral OM β-barrel proteins in Gram-negative bacteria are synthesized in the cytoplasm and trafficked to the OM, where they are locally assembled into the growing OM by the ubiquitous β-barrel assembly machine (Bam). While the identities and structures of all essential and accessory Bam components have been determined, the basic mechanism of Bam-assisted OM protein integration remains elusive. Here we review mechanistic analyses of OM β-barrel protein folding and Bam dynamics and summarize recent insights that inform a general model for OM protein recognition and assembly by the Bam complex.
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Affiliation(s)
- Dante P Ricci
- Department of Early Research, Achaogen, Inc., South San Francisco, CA 94080
| | - Thomas J Silhavy
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544
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21
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Humes JR, Schiffrin B, Calabrese AN, Higgins AJ, Westhead DR, Brockwell DJ, Radford SE. The Role of SurA PPIase Domains in Preventing Aggregation of the Outer-Membrane Proteins tOmpA and OmpT. J Mol Biol 2019; 431:1267-1283. [PMID: 30716334 DOI: 10.1016/j.jmb.2019.01.032] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2018] [Revised: 01/22/2019] [Accepted: 01/25/2019] [Indexed: 10/27/2022]
Abstract
SurA is a conserved ATP-independent periplasmic chaperone involved in the biogenesis of outer-membrane proteins (OMPs). Escherichia coli SurA has a core domain and two peptidylprolyl isomerase (PPIase) domains, the role(s) of which remain unresolved. Here we show that while SurA homologues in early proteobacteria typically contain one or no PPIase domains, the presence of two PPIase domains is common in SurA in later proteobacteria, implying an evolutionary advantage for this domain architecture. Bioinformatics analysis of >350,000 OMP sequences showed that their length, hydrophobicity and aggregation propensity are similar across the proteobacterial classes, ruling out a simple correlation between SurA domain architecture and these properties of OMP sequences. To investigate the role of the PPIase domains in SurA activity, we deleted one or both PPIase domains from E.coli SurA and investigated the ability of the resulting proteins to bind and prevent the aggregation of tOmpA (19 kDa) and OmpT (33 kDa). The results show that wild-type SurA inhibits the aggregation of both OMPs, as do the cytoplasmic OMP chaperones trigger factor and SecB. However, while the ability of SurA to bind and prevent tOmpA aggregation does not depend on its PPIase domains, deletion of even a single PPIase domain ablates the ability of SurA to prevent OmpT aggregation. The results demonstrate that the core domain of SurA endows its generic chaperone ability, while the presence of PPIase domains enhances its chaperone activity for specific OMPs, suggesting one reason for the conservation of multiple PPIase domains in SurA in proteobacteria.
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Affiliation(s)
- Julia R Humes
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Bob Schiffrin
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Antonio N Calabrese
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Anna J Higgins
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - David R Westhead
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - David J Brockwell
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.
| | - Sheena E Radford
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.
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22
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Substrate specificities in Salmonella typhi outer membrane protease (PgtE) from omptin family – An in silico proteomic approach. INFORMATICS IN MEDICINE UNLOCKED 2019. [DOI: 10.1016/j.imu.2019.100237] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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23
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The Escherichia coli β-Barrel Assembly Machinery Is Sensitized to Perturbations under High Membrane Fluidity. J Bacteriol 2018; 201:JB.00517-18. [PMID: 30322857 PMCID: PMC6287456 DOI: 10.1128/jb.00517-18] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 10/08/2018] [Indexed: 01/08/2023] Open
Abstract
BamA is an essential component of the β-barrel assembly machine (BAM) in the outer membranes of Gram-negative bacteria. We have used a recently described inhibitory anti-BamA antibody, MAB1, to identify the molecular requirements for BAM function. Resistance to this antibody can be achieved through changes to the outer membrane or by amino acid substitutions in BamA that allosterically affect the response to MAB1. Sensitivity to MAB1 is achieved by perturbing BAM function. By using MAB1 activity and functional assays as proxies for BAM function, we link outer membrane fluidity to BamA activity, demonstrating that an increase in membrane fluidity sensitizes the cells to BAM perturbations. Thus, the search for potential inhibitors of BamA function must consider the membrane environment in which β-barrel folding occurs. Integral β-barrel membrane proteins are folded and inserted into the Gram-negative bacterial outer membrane by the β-barrel assembly machine (BAM). This essential complex, composed of a β-barrel protein, BamA, and four lipoproteins, BamB, BamC, BamD, and BamE, resides in the outer membrane, a unique asymmetrical lipid bilayer that is difficult to recapitulate in vitro. Thus, the probing of BAM function in living cells is critical to fully understand the mechanism of β-barrel folding. We recently identified an anti-BamA monoclonal antibody, MAB1, that is a specific and potent inhibitor of BamA function. Here, we show that the inhibitory effect of MAB1 is enhanced when BAM function is perturbed by either lowering the level of BamA or removing the nonessential BAM lipoproteins, BamB, BamC, or BamE. The disruption of BAM reduces BamA activity, increases outer membrane (OM) fluidity, and activates the σE stress response, suggesting the OM environment and BAM function are interconnected. Consistent with this idea, an increase in the membrane fluidity through changes in the growth environment or alterations to the lipopolysaccharide in the outer membrane is sufficient to provide resistance to MAB1 and enable the BAM to tolerate these perturbations. Amino acid substitutions in BamA at positions in the outer membrane spanning region or the periplasmic space remote from the extracellular MAB1 binding site also provide resistance to the inhibitory antibody. Our data highlight that the outer membrane environment is a critical determinant in the efficient and productive folding of β-barrel membrane proteins by BamA. IMPORTANCE BamA is an essential component of the β-barrel assembly machine (BAM) in the outer membranes of Gram-negative bacteria. We have used a recently described inhibitory anti-BamA antibody, MAB1, to identify the molecular requirements for BAM function. Resistance to this antibody can be achieved through changes to the outer membrane or by amino acid substitutions in BamA that allosterically affect the response to MAB1. Sensitivity to MAB1 is achieved by perturbing BAM function. By using MAB1 activity and functional assays as proxies for BAM function, we link outer membrane fluidity to BamA activity, demonstrating that an increase in membrane fluidity sensitizes the cells to BAM perturbations. Thus, the search for potential inhibitors of BamA function must consider the membrane environment in which β-barrel folding occurs.
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24
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Ebbensgaard A, Mordhorst H, Aarestrup FM, Hansen EB. The Role of Outer Membrane Proteins and Lipopolysaccharides for the Sensitivity of Escherichia coli to Antimicrobial Peptides. Front Microbiol 2018; 9:2153. [PMID: 30245684 PMCID: PMC6137088 DOI: 10.3389/fmicb.2018.02153] [Citation(s) in RCA: 92] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2018] [Accepted: 08/22/2018] [Indexed: 01/20/2023] Open
Abstract
Bacterial resistance to classical antibiotics is emerging worldwide. The number of infections caused by multidrug resistant bacteria is increasing and becoming a serious threat for human health globally. In particular, Gram-negative pathogens including multidrug resistant Escherichia coli are of serious concern being resistant to the currently available antibiotics. All Gram-negative bacteria are enclosed by an outer membrane which acts as an additional protection barrier preventing the entry of toxic compounds including antibiotics and antimicrobial peptides (AMPs). In this study we report that the outer membrane component lipopolysaccharide (LPS) plays a crucial role for the antimicrobial susceptibility of E. coli BW25113 against the cationic AMPs Cap18, Cap11, Cap11-1-18m2, melittin, indolicidin, cecropin P1, cecropin B, and the polypeptide antibiotic colistin, whereas the outer membrane protease OmpT and the lipoprotein Lpp only play a minor role for the susceptibility against cationic AMPs. Increased susceptibility toward cationic AMPs was found for LPS deficient mutants of E. coli BW25113 harboring deletions in any of the genes required for the inner part of core-oligosaccharide of the LPS, waaC, waaE, waaF, waaG, and gmhA. In addition, our study demonstrates that the antimicrobial activity of Cap18, Cap11, Cap11-1-18m2, cecropin B, and cecropin P1 is not only dependent on the inner part of the core oligosaccharide, but also on the outer part and its sugar composition. Finally, we demonstrated that the antimicrobial activity of selected Cap18 derivatives harboring amino acid substitutions in the hydrophobic interface, are non-active against wild-type E. coli ATCC29522. By deleting waaC, waaE, waaF, or waaG the antimicrobial activity of the non-active derivatives can be partially or fully restored, suggesting a very close interplay between the LPS core oligosaccharide and the specific Cap18 derivative. Summarizing, this study implicates that the nature of the outer membrane component LPS has a big impact on the antimicrobial activity of cationic AMPs against E. coli. In particular, the inner as well as the outer part of the core oligosaccharide are important elements determining the antimicrobial susceptibility of E. coli against cationic AMPs.
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Affiliation(s)
- Anna Ebbensgaard
- National Food Institute, Technical University of Denmark, Kongens Lyngby, Denmark.,Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Hanne Mordhorst
- National Food Institute, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Frank M Aarestrup
- National Food Institute, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Egon B Hansen
- National Food Institute, Technical University of Denmark, Kongens Lyngby, Denmark
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25
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Assembly, Biochemical Characterization, Immunogenicity, Adjuvanticity, and Efficacy of Shigella Artificial Invaplex. mSphere 2018; 3:mSphere00583-17. [PMID: 29600284 PMCID: PMC5874444 DOI: 10.1128/msphere.00583-17] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Accepted: 02/02/2018] [Indexed: 11/20/2022] Open
Abstract
The native Invaplex (InvaplexNAT) vaccine and adjuvant is an ion exchange-purified product derived from the water extract of virulent Shigella species. The key component of InvaplexNAT is a high-molecular-mass complex (HMMC) consisting of the Shigella lipopolysaccharide (LPS) and the invasin proteins IpaB and IpaC. To improve product purity and immunogenicity, artificial Invaplex (InvaplexAR) was developed using recombinant IpaB and IpaC proteins and purified Shigella LPS to assemble an HMMC consisting of all three components. Characterization of InvaplexAR by various methods demonstrated similar characteristics as the previously reported HMMC in InvaplexNAT. The well-defined InvaplexAR vaccine consistently contained greater quantities of IpaB, IpaC, and LPS than InvaplexNAT. InvaplexAR and InvaplexNAT immunogenicities were compared in mouse and guinea pig dose escalation studies. In both models, immunization induced antibody responses specific for InvaplexNAT and LPS while InvaplexAR induced markedly higher anti-IpaB and -IpaC serum IgG and IgA endpoint titers. In the murine model, homologous protection was achieved with 10-fold less InvaplexAR than InvaplexNAT and mice receiving InvaplexAR lost significantly less weight than mice receiving the same amount of InvaplexNAT. Moreover, mice immunized with InvaplexAR were protected from challenge with both homologous and heterologous Shigella serotypes. Guinea pigs receiving approximately 5-fold less InvaplexAR compared to cohorts immunized with InvaplexNAT were protected from ocular challenge. Furthermore, adjuvanticity previously attributed to InvaplexNAT was retained with InvaplexAR. The second-generation Shigella Invaplex vaccine, InvaplexAR, offers significant advantages over InvaplexNAT in reproducibility, flexible yet defined composition, immunogenicity, and protective efficacy. IMPORTANCEShigella species are bacteria that cause severe diarrheal disease worldwide, primarily in young children. Treatment of shigellosis includes oral fluids and antibiotics, but the high burden of disease, increasing prevalence of antibiotic resistance, and long-term health consequences clearly warrant the development of an effective vaccine. One Shigella vaccine under development is termed the invasin complex or Invaplex and is designed to drive an immune response to specific antigens of the bacteria in an effort to protect an individual from infection. The work presented here describes the production and evaluation of a new generation of Invaplex. The improved vaccine stimulates the production of antibodies in immunized mice and guinea pigs and protects these animals from Shigella infection. The next step in the product's development will be to test the safety and immune response induced in humans immunized with Invaplex.
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Substrate specificities in Salmonella typhi outer membrane protease (PgtE) from Omptin family – An in silico proteomic approach. INFORMATICS IN MEDICINE UNLOCKED 2018. [DOI: 10.1016/j.imu.2018.05.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Wood SE, Sinsinbar G, Gudlur S, Nallani M, Huang CF, Liedberg B, Mrksich M. A Bottom-Up Proteomic Approach to Identify Substrate Specificity of Outer-Membrane Protease OmpT. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201707535] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Sarah E. Wood
- Departments of Chemistry and Biomedical Engineering; Northwestern University; 2145 Sheridan Road Evanston IL 60208 USA
| | - Gaurav Sinsinbar
- Center for Biomimetic Sensor Science; School of Materials Science & Engineering; Nanyang Technological University; 50 Nanyang Drive 637553 Singapore
| | - Sushanth Gudlur
- Center for Biomimetic Sensor Science; School of Materials Science & Engineering; Nanyang Technological University; 50 Nanyang Drive 637553 Singapore
| | - Madhavan Nallani
- Center for Biomimetic Sensor Science; School of Materials Science & Engineering; Nanyang Technological University; 50 Nanyang Drive 637553 Singapore
| | - Che-Fan Huang
- Departments of Chemistry and Biomedical Engineering; Northwestern University; 2145 Sheridan Road Evanston IL 60208 USA
| | - Bo Liedberg
- Center for Biomimetic Sensor Science; School of Materials Science & Engineering; Nanyang Technological University; 50 Nanyang Drive 637553 Singapore
| | - Milan Mrksich
- Departments of Chemistry and Biomedical Engineering; Northwestern University; 2145 Sheridan Road Evanston IL 60208 USA
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Wood SE, Sinsinbar G, Gudlur S, Nallani M, Huang CF, Liedberg B, Mrksich M. A Bottom-Up Proteomic Approach to Identify Substrate Specificity of Outer-Membrane Protease OmpT. Angew Chem Int Ed Engl 2017; 56:16531-16535. [DOI: 10.1002/anie.201707535] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 09/06/2017] [Indexed: 12/22/2022]
Affiliation(s)
- Sarah E. Wood
- Departments of Chemistry and Biomedical Engineering; Northwestern University; 2145 Sheridan Road Evanston IL 60208 USA
| | - Gaurav Sinsinbar
- Center for Biomimetic Sensor Science; School of Materials Science & Engineering; Nanyang Technological University; 50 Nanyang Drive 637553 Singapore
| | - Sushanth Gudlur
- Center for Biomimetic Sensor Science; School of Materials Science & Engineering; Nanyang Technological University; 50 Nanyang Drive 637553 Singapore
| | - Madhavan Nallani
- Center for Biomimetic Sensor Science; School of Materials Science & Engineering; Nanyang Technological University; 50 Nanyang Drive 637553 Singapore
| | - Che-Fan Huang
- Departments of Chemistry and Biomedical Engineering; Northwestern University; 2145 Sheridan Road Evanston IL 60208 USA
| | - Bo Liedberg
- Center for Biomimetic Sensor Science; School of Materials Science & Engineering; Nanyang Technological University; 50 Nanyang Drive 637553 Singapore
| | - Milan Mrksich
- Departments of Chemistry and Biomedical Engineering; Northwestern University; 2145 Sheridan Road Evanston IL 60208 USA
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Watkinson TG, Calabrese AN, Ault JR, Radford SE, Ashcroft AE. FPOP-LC-MS/MS Suggests Differences in Interaction Sites of Amphipols and Detergents with Outer Membrane Proteins. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2017; 28:50-55. [PMID: 27343183 PMCID: PMC5174144 DOI: 10.1007/s13361-016-1421-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 05/10/2016] [Accepted: 05/11/2016] [Indexed: 05/24/2023]
Abstract
Amphipols are a class of novel surfactants that are capable of stabilizing the native state of membrane proteins. They have been shown to be highly effective, in some cases more so than detergent micelles, at maintaining the structural integrity of membrane proteins in solution, and have shown promise as vehicles for delivering native membrane proteins into the gas phase for structural interrogation. Here, we use fast photochemical oxidation of proteins (FPOP), which irreversibly labels the side chains of solvent-accessible residues with hydroxyl radicals generated by laser photolysis of hydrogen peroxide, to compare the solvent accessibility of the outer membrane protein OmpT when solubilized with the amphipol A8-35 or with n-dodecyl-β-maltoside (DDM) detergent micelles. Using quantitative mass spectrometry analyses, we show that fast photochemical oxidation reveals differences in the extent of solvent accessibility of residues between the A8-35 and DDM solubilized states, providing a rationale for the increased stability of membrane proteins solubilized with amphipol compared with detergent micelles, as a result of additional intermolecular contacts. Graphical Abstract ᅟ.
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Affiliation(s)
- Thomas G Watkinson
- Astbury Center for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Antonio N Calabrese
- Astbury Center for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - James R Ault
- Astbury Center for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Sheena E Radford
- Astbury Center for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, UK.
| | - Alison E Ashcroft
- Astbury Center for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, UK.
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Danoff EJ, Fleming KG. Novel Kinetic Intermediates Populated along the Folding Pathway of the Transmembrane β-Barrel OmpA. Biochemistry 2016; 56:47-60. [PMID: 28001375 DOI: 10.1021/acs.biochem.6b00809] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We examined the folding of the β-barrel membrane protein OmpA from Escherichia coli. Although previous studies identified several intermediate states followed by a concerted translocation mechanism across the bilayer, some aspects of the pathway were still unclear, including the extent of secondary structure formation in the intermediate states and how the mechanism gave rise to multiple exponential phases in the folding kinetics. We addressed these questions by investigating the folding kinetics of the OmpA transmembrane β-barrel domain over a range of bilayer thicknesses, allowing us to observe different regions of the folding pathway. The fastest folding into the thinnest bilayers provided information about the later stages of the process, and the slowest folding into thicker bilayers revealed early kinetic steps. Folding was monitored using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and circular dichroism spectroscopy, which provide complementary information about tertiary and secondary structure formation. We globally fit the folding data to kinetic schemes and found that the same core pathway was followed under all lipid conditions. We propose a multistep folding mechanism for OmpA that includes unstructured surface-adsorbed states converting through a partially inserted state with substantial β-sheet structure to the final natively inserted barrel. Kinetic models show that all steps of the main folding pathway are accelerated by membrane defects that occur as a result of thinning the bilayer or incubation of lipids at the phase transition temperature. In addition to suppressing off-pathway states, β-barrel assembly machinery-catalyzed folding in vivo could accelerate any or all of these main folding steps to ensure efficient outer membrane protein biogenesis in vivo.
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Affiliation(s)
- Emily J Danoff
- T. C. Jenkins Department of Biophysics, Johns Hopkins University , Baltimore, Maryland 21218, United States
| | - Karen G Fleming
- T. C. Jenkins Department of Biophysics, Johns Hopkins University , Baltimore, Maryland 21218, United States
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Iadanza MG, Higgins AJ, Schiffrin B, Calabrese AN, Brockwell DJ, Ashcroft AE, Radford SE, Ranson NA. Lateral opening in the intact β-barrel assembly machinery captured by cryo-EM. Nat Commun 2016; 7:12865. [PMID: 27686148 PMCID: PMC5056442 DOI: 10.1038/ncomms12865] [Citation(s) in RCA: 138] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 08/04/2016] [Indexed: 02/06/2023] Open
Abstract
The β-barrel assembly machinery (BAM) is a ∼203 kDa complex of five proteins (BamA-E), which is essential for viability in E. coli. BAM promotes the folding and insertion of β-barrel proteins into the outer membrane via a poorly understood mechanism. Several current models suggest that BAM functions through a 'lateral gating' motion of the β-barrel of BamA. Here we present a cryo-EM structure of the BamABCDE complex, at 4.9 Å resolution. The structure is in a laterally open conformation showing that gating is independent of BamB binding. We describe conformational changes throughout the complex and interactions between BamA, B, D and E, and the detergent micelle that suggest communication between BAM and the lipid bilayer. Finally, using an enhanced reconstitution protocol and functional assays, we show that for the outer membrane protein OmpT, efficient folding in vitro requires lateral gating in BAM.
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Affiliation(s)
- Matthew G. Iadanza
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, Mount Preston Street, Leeds LS2 9JT, UK
| | - Anna J. Higgins
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, Mount Preston Street, Leeds LS2 9JT, UK
| | - Bob Schiffrin
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, Mount Preston Street, Leeds LS2 9JT, UK
| | - Antonio N. Calabrese
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, Mount Preston Street, Leeds LS2 9JT, UK
| | - David J. Brockwell
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, Mount Preston Street, Leeds LS2 9JT, UK
| | - Alison E. Ashcroft
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, Mount Preston Street, Leeds LS2 9JT, UK
| | - Sheena E. Radford
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, Mount Preston Street, Leeds LS2 9JT, UK
| | - Neil A. Ranson
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, Mount Preston Street, Leeds LS2 9JT, UK
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Palomo V, Díaz SA, Stewart MH, Susumu K, Medintz IL, Dawson PE. 3,4-Dihydroxyphenylalanine Peptides as Nonperturbative Quantum Dot Sensors of Aminopeptidase. ACS NANO 2016; 10:6090-9. [PMID: 27206058 PMCID: PMC4968404 DOI: 10.1021/acsnano.6b01682] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Fluorescence-based assays for hydrolases that cleave within the substrate (endopeptidases) are common, while developing substrates for proteases that selectively cleave from peptide termini (exopeptidases) is more challenging, since the termini are specifically recognized by the enzyme and cannot be modified to facilitate a Förster resonance energy transfer (FRET)-based approach. The development of a robust system that enables the quenching of fluorescent particles by simple amino acid side chains would find broad utility for peptide sensors and would be advantageous for exopeptidases. Here we describe a quantum dot (QD)-based electron transfer (ET) sensor that is able to allow direct, quantitative monitoring of both exopeptidase and endopeptidase activity. The incorporation of 3,4-dihydroxyphenylalanine (DOPA) into the sequence of a peptide allows for the quenching of QD photoluminescence through an ET mechanism. DOPA is a nonproteinogenic amino acid that can replace a phenylalanine or tyrosine residue in a peptide sequence without severely altering structural properties, allowing for its introduction at multiple positions within a biologically active peptide substrate. Consequently, the quenching system presented here is ideally suited for incorporation into diverse peptide substrates for enzyme recognition, digestion, and activity sensing. Our findings suggest a broad utility of a small ET-capable amino acid side chain in detecting enzyme activity through ET-mediated QD luminescence quenching.
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Affiliation(s)
- Valle Palomo
- Department of Chemistry, The Scripps Research Institute, La Jolla, California, 92037 (USA)
| | - Sebastián A. Díaz
- Center for Bio/Molecular Science and Engineering, Code 6900, U.S. Naval Research Laboratory, Washington, D.C., 20375 (USA)
| | - Michael H. Stewart
- Optical Sciences Division, Code 5611, U.S. Naval Research Laboratory, Washington, D.C., 20375 (USA)
| | - Kimihiro Susumu
- Optical Sciences Division, Code 5611, U.S. Naval Research Laboratory, Washington, D.C., 20375 (USA)
| | - Igor L. Medintz
- Center for Bio/Molecular Science and Engineering, Code 6900, U.S. Naval Research Laboratory, Washington, D.C., 20375 (USA)
| | - Philip E. Dawson
- Department of Chemistry, The Scripps Research Institute, La Jolla, California, 92037 (USA)
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Watkinson TG, Calabrese AN, Giusti F, Zoonens M, Radford SE, Ashcroft AE. Systematic analysis of the use of amphipathic polymers for studies of outer membrane proteins using mass spectrometry. INTERNATIONAL JOURNAL OF MASS SPECTROMETRY 2015; 391:54-61. [PMID: 26869850 PMCID: PMC4708066 DOI: 10.1016/j.ijms.2015.06.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 06/19/2015] [Accepted: 06/26/2015] [Indexed: 05/10/2023]
Abstract
Membrane proteins (MPs) are essential for numerous important biological processes. Recently, mass spectrometry (MS), coupled with an array of related techniques, has been used to probe the structural properties of MPs and their complexes. Typically, detergent micelles have been employed for delivering MPs into the gas-phase, but these complexes have intrinsic properties that can limit the utility of structural studies of MPs using MS methods. Amphipols (APols) have advantages over detergent micelles and have been shown to be capable of delivering native MPs into the gas-phase. Comparing six different APols which vary in mass and charge, and the detergent n-dodecyl-β-d-maltopyranoside, we aimed to determine which APols are most efficient for delivery of native outer membrane proteins (OMPs) into the gas-phase. We show that maintaining the solution-phase folding and global structures of three different OMPs (PagP, OmpT and tOmpA) are independent of the APol used, but differences in OMP activity can result from the different APol:OMP complexes. ESI-IMS-MS analysis of OMP:APol complexes shows that the A8-35 APol is most proficient at liberating all three OMPs into the gas-phase, without altering their gas-phase conformations.
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Affiliation(s)
- Thomas G. Watkinson
- Astbury Centre for Structural Molecular Biology, School of Molecular & Cellular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Antonio N. Calabrese
- Astbury Centre for Structural Molecular Biology, School of Molecular & Cellular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Fabrice Giusti
- Laboratoire de Physico-Chimie Moléculaire des Protéines Membranaires, UMR 7099, Institut de Biologie Physico-Chimique (FRC 550), Centre National de la Recherche Scientifique/Université Paris-7, 13, rue Pierre-et-Marie-Curie, 75005 Paris, France
| | - Manuela Zoonens
- Laboratoire de Physico-Chimie Moléculaire des Protéines Membranaires, UMR 7099, Institut de Biologie Physico-Chimique (FRC 550), Centre National de la Recherche Scientifique/Université Paris-7, 13, rue Pierre-et-Marie-Curie, 75005 Paris, France
| | - Sheena E. Radford
- Astbury Centre for Structural Molecular Biology, School of Molecular & Cellular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Alison E. Ashcroft
- Astbury Centre for Structural Molecular Biology, School of Molecular & Cellular Biology, University of Leeds, Leeds, LS2 9JT, UK
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Inhibition of outer membrane proteases of the omptin family by aprotinin. Infect Immun 2015; 83:2300-11. [PMID: 25824836 DOI: 10.1128/iai.00136-15] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 03/20/2015] [Indexed: 12/14/2022] Open
Abstract
Bacterial proteases are important virulence factors that inactivate host defense proteins and contribute to tissue destruction and bacterial dissemination. Outer membrane proteases of the omptin family, exemplified by Escherichia coli OmpT, are found in some Gram-negative bacteria. Omptins cleave a variety of substrates at the host-pathogen interface, including plasminogen and antimicrobial peptides. Multiple omptin substrates relevant to infection have been identified; nonetheless, an effective omptin inhibitor remains to be found. Here, we purified native CroP, the OmpT ortholog in the murine pathogen Citrobacter rodentium. Purified CroP was found to readily cleave both a synthetic fluorescence resonance energy transfer substrate and the murine cathelicidin-related antimicrobial peptide. In contrast, CroP was found to poorly activate plasminogen into active plasmin. Although classical protease inhibitors were ineffective against CroP activity, we found that the serine protease inhibitor aprotinin displays inhibitory potency in the micromolar range. Aprotinin was shown to act as a competitive inhibitor of CroP activity and to interfere with the cleavage of the murine cathelicidin-related antimicrobial peptide. Importantly, aprotinin was able to inhibit not only CroP but also Yersinia pestis Pla and, to a lesser extent, E. coli OmpT. We propose a structural model of the aprotinin-omptin complex in which Lys15 of aprotinin forms salt bridges with conserved negatively charged residues of the omptin active site.
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He XL, Wang Q, Peng L, Qu YR, Puthiyakunnon S, Liu XL, Hui CY, Boddu S, Cao H, Huang SH. Role of uropathogenic Escherichia coli outer membrane protein T in pathogenesis of urinary tract infection. Pathog Dis 2015; 73:ftv006. [PMID: 25825479 DOI: 10.1093/femspd/ftv006] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
OmpT is one of the members of the outer membrane protein family that has been identified as a virulence factor in most of the uropathogenic Escherichia coli (UPEC). However, the exact role of OmpT in the urinary tract infections (UTIs) remains unclear. To determine the role of OmpT in the pathogenesis of UPEC, an isogenic deletion mutant of ompT (COTD) was constructed by the λ Red recombination. Human bladder epithelial cell line 5637(HBEC 5637) was used to evaluate the ability of bacterial adhesion/invasion. A murine model of UTI was established to study the formation of intracellular bacterial communities (IBCs) in the process of UTIs. The cytokines were also examined during the pathogenesis. The results showed that the COTD strain was deficient in bacterial adhesion and invasion as well as in IBC formation compare to the parent strain. ELISA quantification analysis of cytokines showed that the levels of TNF-α, IL-6 and IL-8 in the serum, bladder and kidney tissues of the mice infected with COTD were lower than that of the CFT073 group. In summary, these results suggest that OmpT plays a multifaceted role in pathogenesis of UTI, including increased bacterial adhesiveness/invasiveness, formation of IBCs and upregulated proinflammatory cytokines.
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Affiliation(s)
- Xiao Long He
- Department of Microbiology, School of Public Health & Tropical Medicine, Southern Medical University, Guangzhou 510515, China
| | - Qin Wang
- Department of Microbiology, School of Public Health & Tropical Medicine, Southern Medical University, Guangzhou 510515, China
| | - Liang Peng
- Department of Clinical Laboratory, The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou 510260 China
| | - Ya-Rong Qu
- Department of Microbiology, School of Public Health & Tropical Medicine, Southern Medical University, Guangzhou 510515, China
| | - Santhosh Puthiyakunnon
- Department of Microbiology, School of Public Health & Tropical Medicine, Southern Medical University, Guangzhou 510515, China
| | - Xiao-Lu Liu
- Department of Microbiology, School of Public Health & Tropical Medicine, Southern Medical University, Guangzhou 510515, China
| | - Chang Ye Hui
- Shenzhen Prevention and Treatment Center for Occupational Disease, Shenzhen, Guangdong 518001, China
| | - Swapna Boddu
- Department of Microbiology, School of Public Health & Tropical Medicine, Southern Medical University, Guangzhou 510515, China
| | - Hong Cao
- Department of Microbiology, School of Public Health & Tropical Medicine, Southern Medical University, Guangzhou 510515, China
| | - Sheng-He Huang
- Department of Microbiology, School of Public Health & Tropical Medicine, Southern Medical University, Guangzhou 510515, China Children's Hospital Los Angeles, University of Southern California, Los Angeles 90027, USA
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Sichwart S, Tozakidis IEP, Teese M, Jose J. Maximized Autotransporter-Mediated Expression (MATE) for Surface Display and Secretion of Recombinant Proteins in Escherichia coli. Food Technol Biotechnol 2015; 53:251-260. [PMID: 27904356 DOI: 10.17113/ftb.53.03.15.3802] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
A new optimized system for the surface display and secretion of recombinant proteins is described, termed MATE (maximized autotransporter-mediated expression). It is based on an artificial gene consisting of the coding region for the signal peptide of CtxB, a multiple cloning site for passenger gene insertion, flanked by coding sequences for linear epitopes for monoclonal antibodies and OmpT, and factor Xa protease cleavage sites followed by a codon-optimized DNA sequence of the linker and the β-barrel of the type V autotransporter EhaA from Escherichia coli under control of an IPTG-inducible T5 promoter. The MATE system enabled the continuous secretion of recombinant passenger mCherry via OmpT-mediated cleavage, using native OmpT protease activity in E. coli when grown at 37 °C. It is the first example to show that native OmpT activity is sufficient to facilitate the secretion of a correctly folded target protein in preparative amounts obtaining 240 µg of purified mCherry from 800 mL of crude culture supernatant. Because the release of mCherry was achieved by a simple transfer of the encoding plasmid from an OmpT-negative to an OmpT-positive strain, it bears the option to use surface display for screening purposes and secretion for production of the selected variant. A single plasmid could therefore be used for continuous secretion in OmpT-positive strains or surface display in OmpT-negative strains. In conclusion, the MATE system appears to be a versatile tool for the surface display and for the secretion of target proteins in E. coli.
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Affiliation(s)
- Shanna Sichwart
- Institute of Pharmaceutical and Medicinal Chemistry, PharmaCampus, Westphalian Wilhelms-University, Corrensstraße 48, DE-48149 Münster, Germany
| | - Iasson E P Tozakidis
- Institute of Pharmaceutical and Medicinal Chemistry, PharmaCampus, Westphalian Wilhelms-University, Corrensstraße 48, DE-48149 Münster, Germany; The NRW Graduate School of Chemistry, Wilhelm-Klemm-Straße 10, DE-48149 Münster, Germany
| | - Mark Teese
- Institute of Pharmaceutical and Medicinal Chemistry, PharmaCampus, Westphalian Wilhelms-University, Corrensstraße 48, DE-48149 Münster, Germany; Present address: Technical University Munich, Weihenstephaner Berg 3, DE-85354 Freising, Germany
| | - Joachim Jose
- Institute of Pharmaceutical and Medicinal Chemistry, PharmaCampus, Westphalian Wilhelms-University, Corrensstraße 48, DE-48149 Münster, Germany; The NRW Graduate School of Chemistry, Wilhelm-Klemm-Straße 10, DE-48149 Münster, Germany
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Calabrese AN, Watkinson TG, Henderson PJF, Radford SE, Ashcroft AE. Amphipols outperform dodecylmaltoside micelles in stabilizing membrane protein structure in the gas phase. Anal Chem 2014; 87:1118-26. [PMID: 25495802 PMCID: PMC4636139 DOI: 10.1021/ac5037022] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Noncovalent mass spectrometry (MS) is emerging as an invaluable technique to probe the structure, interactions, and dynamics of membrane proteins (MPs). However, maintaining native-like MP conformations in the gas phase using detergent solubilized proteins is often challenging and may limit structural analysis. Amphipols, such as the well characterized A8-35, are alternative reagents able to maintain the solubility of MPs in detergent-free solution. In this work, the ability of A8-35 to retain the structural integrity of MPs for interrogation by electrospray ionization-ion mobility spectrometry-mass spectrometry (ESI-IMS-MS) is compared systematically with the commonly used detergent dodecylmaltoside. MPs from the two major structural classes were selected for analysis, including two β-barrel outer MPs, PagP and OmpT (20.2 and 33.5 kDa, respectively), and two α-helical proteins, Mhp1 and GalP (54.6 and 51.7 kDa, respectively). Evaluation of the rotationally averaged collision cross sections of the observed ions revealed that the native structures of detergent solubilized MPs were not always retained in the gas phase, with both collapsed and unfolded species being detected. In contrast, ESI-IMS-MS analysis of the amphipol solubilized MPs studied resulted in charge state distributions consistent with less gas phase induced unfolding, and the presence of lowly charged ions which exhibit collision cross sections comparable with those calculated from high resolution structural data. The data demonstrate that A8-35 can be more effective than dodecylmaltoside at maintaining native MP structure and interactions in the gas phase, permitting noncovalent ESI-IMS-MS analysis of MPs from the two major structural classes, while gas phase dissociation from dodecylmaltoside micelles leads to significant gas phase unfolding, especially for the α-helical MPs studied.
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Affiliation(s)
- Antonio N Calabrese
- School of Molecular and Cellular Biology and ‡School of Biomedical Sciences, Astbury Centre for Structural Molecular Biology, University of Leeds , Leeds, LS2 9JT, United Kingdom
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Folding membrane proteins in vitro: A table and some comments. Arch Biochem Biophys 2014; 564:314-26. [DOI: 10.1016/j.abb.2014.06.029] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 06/17/2014] [Accepted: 06/23/2014] [Indexed: 12/23/2022]
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39
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Folding and stability of integral membrane proteins in amphipols. Arch Biochem Biophys 2014; 564:327-43. [PMID: 25449655 DOI: 10.1016/j.abb.2014.10.013] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 10/11/2014] [Accepted: 10/22/2014] [Indexed: 11/23/2022]
Abstract
Amphipols (APols) are a family of amphipathic polymers designed to keep transmembrane proteins (TMPs) soluble in aqueous solutions in the absence of detergent. APols have proven remarkably efficient at (i) stabilizing TMPs, as compared to detergent solutions, and (ii) folding them from a denatured state to a native, functional one. The underlying physical-chemical mechanisms are discussed.
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40
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41
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Mora L, de Zamaroczy M. In vivo processing of DNase colicins E2 and E7 is required for their import into the cytoplasm of target cells. PLoS One 2014; 9:e96549. [PMID: 24840776 PMCID: PMC4026351 DOI: 10.1371/journal.pone.0096549] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Accepted: 04/08/2014] [Indexed: 11/19/2022] Open
Abstract
DNase colicins E2 and E7, both of which appropriate the BtuB/Tol translocation machinery to cross the outer membrane, undergo a processing step as they enter the cytoplasm. This endoproteolytic cleavage is essential for their killing action. A processed form of the same size, 18.5 kDa, which corresponds to the C-terminal catalytic domain, was detected in the cytoplasm of bacteria treated with either of the two DNase colicins. The inner-membrane protease FtsH is necessary for the processing that allows the translocation of the colicin DNase domain into the cytoplasm. The processing occurs near residue D420, at the same position as the FtsH-dependent cleavage in RNase colicins E3 and D. The cleavage site is located 30 amino acids upstream of the DNase domain. In contrast, the previously reported periplasm-dependent colicin cleavage, located at R452 in colicin E2, was shown to be generated by the outer-membrane protease OmpT and we show that this cleavage is not physiologically relevant for colicin import. Residue R452, whose mutated derivatives led to toxicity defect, was shown to have no role in colicin processing and translocation, but it plays a key role in the catalytic activity, as previously reported for other DNase colicins. Membrane associated forms of colicins E2 and E7 were detected on target cells as proteinase K resistant peptides, which include both the receptor-binding and DNase domains. A similar, but much less proteinase K-resistant form was also detected with RNase colicin E3. These colicin forms are not relevant for colicin import, but their detection on the cell surface indicates that whole nuclease-colicin molecules are found in a stable association with the outer-membrane receptor BtuB of the target cells.
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Affiliation(s)
- Liliana Mora
- Institut de Biologie Physico-Chimique, CNRS, UPR 9073, Paris, France
| | - Miklos de Zamaroczy
- Institut de Biologie Physico-Chimique, CNRS, UPR 9073, Paris, France
- * E-mail:
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42
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Andersen KK, Otzen DE. Folding of outer membrane protein A in the anionic biosurfactant rhamnolipid. FEBS Lett 2014; 588:1955-60. [PMID: 24735722 DOI: 10.1016/j.febslet.2014.04.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 03/21/2014] [Accepted: 04/02/2014] [Indexed: 01/11/2023]
Abstract
Folding and stability of bacterial outer membrane proteins (OMPs) are typically studied in vitro using model systems such as phospholipid vesicles or surfactant. OMP folding requires surfactant concentrations above the critical micelle concentration (cmc) and usually only occurs in neutral or zwitterionic surfactants, but not in anionic or cationic surfactants. Various Gram-negative bacteria produce the anionic biosurfactant rhamnolipid. Here we show that the OMP OmpA can be folded in rhamnolipid at concentrations above the cmc, though the thermal stability is reduced compared to the non-ionic surfactant dodecyl maltoside. We discuss implications for possible interactions between OMPs and biosurfactants in vivo.
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Affiliation(s)
- Kell K Andersen
- iNANO, Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 14, DK - 8000 Aarhus C, Denmark.
| | - Daniel E Otzen
- iNANO, Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 14, DK - 8000 Aarhus C, Denmark.
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43
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Tong C, Wu Z, Yu L, Fan Z, Chen L, Hu R, Ma J, Song B, Zhu Z, Cui Y. Development of an indirect ELISA for detection of E. Coli antibodies in cow serum using a recombinant OmpT as antigen. J Immunoassay Immunochem 2014; 35:241-55. [PMID: 24654821 DOI: 10.1080/15321819.2013.848812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The aim of this article was to develop an indirect enzyme-linked immunosorbent assay (ELISA) for efficient detection of the infection of E. coli in cattle. OmpT, a highly conserved protease in all E. coli strains, was successfully expressed in E. coli XL-1-Blue strain with PET32a vector. Molecular weight of recombinant protein was identified by analyzing SDS-PAGE and the immunogenicity of OmpT was confirmed by Western Blotting. The recombinant OmpT was then employed as capture antigen in the ELISA. The antigen concentration and serum dilution were determined using a checkerboard titration. Results showed that the optimal concentration of coated antigen was 1 μg/ml at a serum dilution of 1:640 and the cut-off value of the assay was 0.335. In addition, the cross-reactivity assay showed that the OmpT was E. coli specific and the reproducibility experiments displayed good repeatability of the assay. Three hundred and forty cattle serum samples were tested by rOmpT-ELISA and sera coagulation tests. The ELISA has showed relative sensitivity of 100% and specificity of 96.47%. Results of these experiments indicated that the rOmpT-ELISA is a simple, rapid, and convenient method for detection the infection of E. coli with different serotype strains.
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Affiliation(s)
- Chunyu Tong
- a School of Life Science & Biotechnology , Heilongjiang Bayi Agricultural University , Heilongjiang Province , People's Republic of China
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44
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Korhonen TK, Haiko J, Laakkonen L, Järvinen HM, Westerlund-Wikström B. Fibrinolytic and coagulative activities of Yersinia pestis. Front Cell Infect Microbiol 2013; 3:35. [PMID: 23898467 PMCID: PMC3724046 DOI: 10.3389/fcimb.2013.00035] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2012] [Accepted: 07/09/2013] [Indexed: 12/18/2022] Open
Abstract
The outer membrane protease Pla belongs to the omptin protease family spread by horizontal gene transfer into Gram-negative bacteria that infect animals or plants. Pla has adapted to support the life style of the plague bacterium Yersinia pestis. Pla has a β-barrel fold with 10 membrane-spanning β strands and five surface loops, and the barrel surface contains bound lipopolysaccharide (LPS) that is critical for the conformation and the activity of Pla. The biological activity of Pla is influenced by the structure of the surface loops around the active site groove and by temperature-induced LPS modifications. Several of the putative virulence-related functions documented for Pla in vitro address control of the human hemostatic system, i.e., coagulation and fibrinolysis. Pla activates human plasminogen to the serine protease plasmin and activates the physiological plasminogen activator urokinase. Pla also inactivates the protease inhibitors alpha-2-antiplasmin and plasminogen activator inhibitor 1 (PAI-1) and prevents the activation of thrombin-activatable fibrinolysis inhibitor (TAFI). These functions enhance uncontrolled fibrinolysis which is thought to improve Y. pestis dissemination and survival in the mammalian host, and lowered fibrin(ogen) deposition has indeed been observed in mice infected with Pla-positive Y. pestis. However, Pla also inactivates an anticoagulant, the tissue factor (TF) pathway inhibitor, which should increase fibrin formation and clotting. Thus, Pla and Y. pestis have complex interactions with the hemostatic system. Y. pestis modifies its LPS upon transfer to the mammalian host and we hypothesize that the contrasting biological activities of Pla in coagulation and fibrinolysis are influenced by LPS changes during infection.
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Affiliation(s)
- Timo K Korhonen
- General Microbiology, Department of Biosciences, University of Helsinki Helsinki, Finland.
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45
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Mikula KM, Kolodziejczyk R, Goldman A. Yersinia infection tools-characterization of structure and function of adhesins. Front Cell Infect Microbiol 2013; 2:169. [PMID: 23316485 PMCID: PMC3539135 DOI: 10.3389/fcimb.2012.00169] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 12/13/2012] [Indexed: 12/16/2022] Open
Abstract
Among the seventeen species of the Gram-negative genus Yersinia, three have been shown to be virulent and pathogenic to humans and animals-Y. enterocolitica, Y. pseudotuberculosis, and Y. pestis. In order to be so, they are armoured with various factors that help them adhere to tissues and organelles, cross the cellular barrier and escape the immune system during host invasion. The group of proteins that mediate pathogen-host interactions constitute adhesins. Invasin, Ail, YadA, YadB, YadC, Pla, and pH 6 antigen belong to the most prominent and best-known Yersinia adhesins. They act at different times and stages of infection complementing each other by their ability to bind a variety of host molecules such as collagen, fibronectin, laminin, β1 integrins, and complement regulators. All the proteins are anchored in the bacterial outer membrane (OM), often forming rod-like or fimbrial-like structures that protrude to the extracellular milieu. Structural studies have shown that the anchor region forms a β-barrel composed of 8, 10, or 12 antiparallel β-strands. Depending on the protein, the extracellular part can be composed of several domains belonging to the immunoglobulin fold superfamily, or form a coiled-coil structure with globular head domain at the end, or just constitute several loops connecting individual β-strands in the β-barrel. Those extracellular regions define the activity of each adhesin. This review focuses on the structure and function of these important molecules, and their role in pathogenesis.
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Affiliation(s)
- Kornelia M Mikula
- Macromolecular X-Ray Crystallography Group, Structural Biology and Biophysics, Institute of Biotechnology, University of Helsinki Helsinki, Finland ; The National Doctoral Program in Informational and Structural Biology, Åbo Academy Turku, Finland
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46
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Leney A, McMorran LM, Radford SE, Ashcroft AE. Amphipathic polymers enable the study of functional membrane proteins in the gas phase. Anal Chem 2012; 84:9841-7. [PMID: 23072351 PMCID: PMC3977578 DOI: 10.1021/ac302223s] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Accepted: 10/16/2012] [Indexed: 01/11/2023]
Abstract
Membrane proteins are notoriously challenging to analyze using mass spectrometry (MS) because of their insolubility in aqueous solution. Current MS methods for studying intact membrane proteins involve solubilization in detergent. However, detergents can destabilize proteins, leading to protein unfolding and aggregation, or resulting in inactive entities. Amphipathic polymers, termed amphipols, can be used as a substitute for detergents and have been shown to enhance the stability of membrane proteins. Here, we show the utility of amphipols for investigating the structural and functional properties of membrane proteins using electrospray ionization mass spectrometry (ESI-MS). The functional properties of two bacterial outer-membrane β-barrel proteins, OmpT and PagP, in complex with the amphipol A8-35 are demonstrated, and their structural integrities are confirmed in the gas phase using ESI-MS coupled with ion mobility spectrometry (IMS). The data illustrate the power of ESI-IMS-MS in separating distinct populations of amphipathic polymers from the amphipol-membrane complex while maintaining a conformationally "nativelike" membrane protein structure in the gas phase. Together, the data indicate the potential importance and utility of amphipols for the analysis of membrane proteins using MS.
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Affiliation(s)
- Aneika
C. Leney
- Astbury Centre
for Structural Molecular Biology, School
of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Lindsay M. McMorran
- Astbury Centre
for Structural Molecular Biology, School
of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Sheena E. Radford
- Astbury Centre
for Structural Molecular Biology, School
of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Alison E. Ashcroft
- Astbury Centre
for Structural Molecular Biology, School
of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
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47
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Wu C, Tran JC, Zamdborg L, Durbin KR, Li M, Ahlf DR, Early BP, Thomas PM, Sweedler JV, Kelleher NL. A protease for 'middle-down' proteomics. Nat Methods 2012; 9:822-4. [PMID: 22706673 PMCID: PMC3430368 DOI: 10.1038/nmeth.2074] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Accepted: 05/10/2012] [Indexed: 11/15/2022]
Abstract
We developed a method for restricted enzymatic proteolysis using the outer membrane protease T (OmpT) to produce large peptides (> 6.3 kDa on average) for mass spectrometry-based proteomics. Using this approach to analyze prefractionated high-mass HeLa proteins we identified 3,697 unique peptides from 1,038 proteins. We demonstrated the ability of large OmpT peptides to differentiate closely related protein isoforms and to enable the detection of many post-translational modifications.
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Affiliation(s)
- Cong Wu
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
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48
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Ricci DP, Silhavy TJ. The Bam machine: a molecular cooper. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:1067-84. [PMID: 21893027 DOI: 10.1016/j.bbamem.2011.08.020] [Citation(s) in RCA: 134] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Revised: 08/08/2011] [Accepted: 08/15/2011] [Indexed: 11/24/2022]
Abstract
The bacterial outer membrane (OM) is an exceptional biological structure with a unique composition that contributes significantly to the resiliency of Gram-negative bacteria. Since all OM components are synthesized in the cytosol, the cell must efficiently transport OM-specific lipids and proteins across the cell envelope and stably integrate them into a growing membrane. In this review, we discuss the challenges associated with these processes and detail the elegant solutions that cells have evolved to address the topological problem of OM biogenesis. Special attention will be paid to the Bam machine, a highly conserved multiprotein complex that facilitates OM β-barrel folding. This article is part of a Special Issue entitled: Protein Folding in Membranes.
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Affiliation(s)
- Dante P Ricci
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
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49
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Hagan CL, Kahne D. The reconstituted Escherichia coli Bam complex catalyzes multiple rounds of β-barrel assembly. Biochemistry 2011; 50:7444-6. [PMID: 21823654 DOI: 10.1021/bi2010784] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
β-Barrel proteins are folded and inserted into the outer membranes of Escherichia coli by the Bam complex. The Bam complex has been purified and functionally reconstituted in vitro. We report conditions for reconstitution that increase the folding yield 10-fold and allow us to monitor the time course of folding directly. We use these conditions to analyze the effect of a mutation in the Bam complex and to demonstrate the ability of the reconstituted complex to catalyze more than one round of substrate assembly.
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Affiliation(s)
- Christine L Hagan
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
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50
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Chauleau M, Mora L, Serba J, de Zamaroczy M. FtsH-dependent processing of RNase colicins D and E3 means that only the cytotoxic domains are imported into the cytoplasm. J Biol Chem 2011; 286:29397-29407. [PMID: 21700705 DOI: 10.1074/jbc.m111.242354] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
It has long been suggested that the import of nuclease colicins requires protein processing; however it had never been formally demonstrated. Here we show that two RNase colicins, E3 and D, which appropriate two different translocation machineries to cross the outer membrane (BtuB/Tol and FepA/TonB, respectively), undergo a processing step inside the cell that is essential to their killing action. We have detected the presence of the C-terminal catalytic domains of these colicins in the cytoplasm of target bacteria. The same processed forms were identified in both colicin-sensitive cells and in cells immune to colicin because of the expression of the cognate immunity protein. We demonstrate that the inner membrane protease FtsH is necessary for the processing of colicins D and E3 during their import. We also show that the signal peptidase LepB interacts directly with the central domain of colicin D in vitro and that it is a specific but not a catalytic requirement for in vivo processing of colicin D. The interaction of colicin D with LepB may ensure a stable association with the inner membrane that in turn allows the colicin recognition by FtsH. We have also shown that the outer membrane protease OmpT is responsible for alternative and distinct endoproteolytic cleavages of colicins D and E3 in vitro, presumably reflecting its known role in the bacterial defense against antimicrobial peptides. Even though the OmpT-catalyzed in vitro cleavage also liberates the catalytic domain from colicins D and E3, it is not involved in the processing of nuclease colicins during their import into the cytoplasm.
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Affiliation(s)
- Mathieu Chauleau
- CNRS, UPR 9073, Institut de Biologie Physico-Chimique, 75005 Paris, France
| | - Liliana Mora
- CNRS, UPR 9073, Institut de Biologie Physico-Chimique, 75005 Paris, France
| | - Justyna Serba
- CNRS, UPR 9073, Institut de Biologie Physico-Chimique, 75005 Paris, France
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