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Ma Y, Pirolo M, Jana B, Mebus VH, Guardabassi L. The intrinsic macrolide resistome of Escherichia coli. Antimicrob Agents Chemother 2024:e0045224. [PMID: 38940570 DOI: 10.1128/aac.00452-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Accepted: 05/16/2024] [Indexed: 06/29/2024] Open
Abstract
Intrinsic resistance to macrolides in Gram-negative bacteria is primarily attributed to the low permeability of the outer membrane, though the underlying genetic and molecular mechanisms remain to be fully elucidated. Here, we used transposon directed insertion-site sequencing (TraDIS) to identify chromosomal non-essential genes involved in Escherichia coli intrinsic resistance to a macrolide antibiotic, tilmicosin. We constructed two highly saturated transposon mutant libraries of >290,000 and >390,000 unique Tn5 insertions in a clinical enterotoxigenic strain (ETEC5621) and in a laboratory strain (K-12 MG1655), respectively. TraDIS analysis identified genes required for growth of ETEC5621 and MG1655 under 1/8 MIC (n = 15 and 16, respectively) and 1/4 MIC (n = 38 and 32, respectively) of tilmicosin. For both strains, 23 genes related to lipopolysaccharide biosynthesis, outer membrane assembly, the Tol-Pal system, efflux pump, and peptidoglycan metabolism were enriched in the presence of the antibiotic. Individual deletion of genes (n = 10) in the wild-type strains led to a 64- to 2-fold reduction in MICs of tilmicosin, erythromycin, and azithromycin, validating the results of the TraDIS analysis. Notably, deletion of surA or waaG, which impairs the outer membrane, led to the most significant decreases in MICs of all three macrolides in ETEC5621. Our findings contribute to a genome-wide understanding of intrinsic macrolide resistance in E. coli, shedding new light on the potential role of the peptidoglycan layer. They also provide an in vitro proof of concept that E. coli can be sensitized to macrolides by targeting proteins maintaining the outer membrane such as SurA and WaaG.
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Affiliation(s)
- Yibing Ma
- Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Mattia Pirolo
- Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Bimal Jana
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Viktor Hundtofte Mebus
- Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Luca Guardabassi
- Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg, Denmark
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Scaletti ER, Pettersson P, Patrick J, Shilling PJ, Westergren RG, Daley DO, Mäler L, Widmalm G, Stenmark P. Structural and functional insights into the Pseudomonas aeruginosa glycosyltransferase WaaG and the implications for lipopolysaccharide biosynthesis. J Biol Chem 2023; 299:105256. [PMID: 37716703 PMCID: PMC10579960 DOI: 10.1016/j.jbc.2023.105256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 08/31/2023] [Accepted: 09/10/2023] [Indexed: 09/18/2023] Open
Abstract
The glycosyltransferase WaaG in Pseudomonas aeruginosa (PaWaaG) is involved in the synthesis of the core region of lipopolysaccharides. It is a promising target for developing adjuvants that could help in the uptake of antibiotics. Herein, we have determined structures of PaWaaG in complex with the nucleotide-sugars UDP-glucose, UDP-galactose, and UDP-GalNAc. Structural comparison with the homolog from Escherichia coli (EcWaaG) revealed five key differences in the sugar-binding pocket. Solution-state NMR analysis showed that WT PaWaaG specifically hydrolyzes UDP-GalNAc and unlike EcWaaG, does not hydrolyze UDP-glucose. Furthermore, we found that a PaWaaG mutant (Y97F/T208R/N282A/T283A/T285I) designed to resemble the EcWaaG sugar binding site, only hydrolyzed UDP-glucose, underscoring the importance of the identified amino acids in substrate specificity. However, neither WT PaWaaG nor the PaWaaG mutant capable of hydrolyzing UDP-glucose was able to complement an E. coli ΔwaaG strain, indicating that more remains to be uncovered about the function of PaWaaG in vivo. This structural and biochemical information will guide future structure-based drug design efforts targeting PaWaaG.
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Affiliation(s)
- Emma R Scaletti
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Pontus Pettersson
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Joan Patrick
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Patrick J Shilling
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | | | - Daniel O Daley
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Lena Mäler
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Göran Widmalm
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm, Sweden
| | - Pål Stenmark
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden.
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Riu F, Ruda A, Engström O, Muheim C, Mobarak H, Ståhle J, Kosma P, Carta A, Daley DO, Widmalm G. A Lead-Based Fragment Library Screening of the Glycosyltransferase WaaG from Escherichia coli. Pharmaceuticals (Basel) 2022; 15:ph15020209. [PMID: 35215321 PMCID: PMC8877264 DOI: 10.3390/ph15020209] [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: 01/15/2022] [Revised: 02/05/2022] [Accepted: 02/06/2022] [Indexed: 11/16/2022] Open
Abstract
Glucosyl transferase I (WaaG) in E. coli catalyzes the transfer of an α-d-glucosyl group to the inner core of the lipopolysaccharide (LPS) and plays an important role in the biogenesis of the outer membrane. If its activity could be inhibited, the integrity of the outer membrane would be compromised and the bacterium would be susceptible to antibiotics that are normally prevented from entering the cell. Herein, three libraries of molecules (A, B and C) were docked in the binding pocket of WaaG, utilizing the docking binding affinity as a filter to select fragment-based compounds for further investigations. From the results of the docking procedure, a selection of compounds was investigated by molecular dynamics (MD) simulations to obtain binding free energy (BFE) and KD values for ligands as an evaluation for the binding to WaaG. Derivatives of 1,3-thiazoles (A7 and A4) from library A and 1,3,4-thiadiazole (B33) from library B displayed a promising profile of BFE, with KD < mM, viz., 0.11, 0.62 and 0.04 mM, respectively. Further root-mean-square-deviation (RMSD), electrostatic/van der Waals contribution to the binding and H-bond interactions displayed a favorable profile for ligands A4 and B33. Mannose and/or heptose-containing disaccharides C1–C4, representing sub-structures of the inner core of the LPS, were also investigated by MD simulations, and compound C42− showed a calculated KD = 0.4 µM. In the presence of UDP-Glc2−, the best-docked pose of disaccharide C42− is proximate to the glucose-binding site of WaaG. A study of the variation in angle and distance was performed on the different portions of WaaG (N-, the C- domains and the hinge region). The Spearman correlation coefficient between the two variables was close to unity, where both variables increase in the same way, suggesting a conformational rearrangement of the protein during the MD simulation, revealing molecular motions of the enzyme that may be part of the catalytic cycle. Selected compounds were also analyzed by Saturation Transfer Difference (STD) NMR experiments. STD effects were notable for the 1,3-thiazole derivatives A4, A8 and A15 with the apo form of the protein as well as in the presence of UDP for A4.
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Affiliation(s)
- Federico Riu
- Department of Medical, Surgical and Experimental Sciences, University of Sassari, Via Muroni, 23A, 07100 Sassari, Italy; (F.R.); (A.C.)
| | - Alessandro Ruda
- Arrhenius Laboratory, Department of Organic Chemistry, Stockholm University, S-106 91 Stockholm, Sweden; (A.R.); (O.E.); (H.M.); (J.S.)
| | - Olof Engström
- Arrhenius Laboratory, Department of Organic Chemistry, Stockholm University, S-106 91 Stockholm, Sweden; (A.R.); (O.E.); (H.M.); (J.S.)
| | - Claudio Muheim
- Arrhenius Laboratory, Department of Biochemistry and Biophysics, Stockholm University, S-106 91 Stockholm, Sweden; (C.M.); (D.O.D.)
| | - Hani Mobarak
- Arrhenius Laboratory, Department of Organic Chemistry, Stockholm University, S-106 91 Stockholm, Sweden; (A.R.); (O.E.); (H.M.); (J.S.)
| | - Jonas Ståhle
- Arrhenius Laboratory, Department of Organic Chemistry, Stockholm University, S-106 91 Stockholm, Sweden; (A.R.); (O.E.); (H.M.); (J.S.)
| | - Paul Kosma
- Department of Chemistry, University of Natural Resources and Life Sciences—Vienna, 1190 Vienna, Austria;
| | - Antonio Carta
- Department of Medical, Surgical and Experimental Sciences, University of Sassari, Via Muroni, 23A, 07100 Sassari, Italy; (F.R.); (A.C.)
| | - Daniel O. Daley
- Arrhenius Laboratory, Department of Biochemistry and Biophysics, Stockholm University, S-106 91 Stockholm, Sweden; (C.M.); (D.O.D.)
| | - Göran Widmalm
- Arrhenius Laboratory, Department of Organic Chemistry, Stockholm University, S-106 91 Stockholm, Sweden; (A.R.); (O.E.); (H.M.); (J.S.)
- Correspondence:
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Extraction of ADP-Heptose and Kdo2-Lipid A from E. coli Deficient in the Heptosyltransferase I Gene. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11188314] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The enzymes involved in lipopolysaccharide (LPS) biosynthesis, including Heptosyltransferase I (HepI), are critical for maintaining the integrity of the bacterial cell wall, and therefore these LPS biosynthetic enzymes are validated targets for drug discovery to treat Gram-negative bacterial infections. Enzymes involved in the biosynthesis of lipopolysaccharides (LPSs) utilize substrates that are synthetically complex, with numerous stereocenters and site-specific glycosylation patterns. Due to the relatively complex substrate structures, characterization of these enzymes has necessitated strategies to generate bacterial cells with gene disruptions to enable the extraction of these substrates from large scale bacterial growths. Like many LPS biosynthetic enzymes, Heptosyltransferase I binds two substrates: the sugar acceptor substrate, Kdo2-Lipid A, and the sugar donor substrate, ADP-l-glycero-d-manno-heptose (ADPH). HepI characterization experiments require copious amounts of Kdo2-Lipid A and ADPH, and unsuccessful extractions of these two substrates can lead to serious delays in collection of data. While there are papers and theses with protocols for extraction of these substrates, they are often missing small details essential to the success of the extraction. Herein detailed protocols are given for extraction of ADPH and Kdo2-Lipid A (KLA) from E. coli, which have had proven success in the Taylor lab. Key steps in the extraction of ADPH are clearing the extract through ultracentrifugation and keeping all water that touches anything in the extraction, including filters, at a pH of 8.0. Key steps in the extraction of KLA are properly lysing the dried down cells before starting the extraction, maximizing yield by allowing precipitate to form overnight, appropriately washing the pellet with phenol and dissolving the KLA in 1% TEA using visual cues, rather than a specific volume. These protocols led to increased yield and a higher success rate of extractions thereby enabling the characterization of HepI.
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Liebau J, Fu B, Brown C, Mäler L. New insights into the membrane association mechanism of the glycosyltransferase WaaG from Escherichia coli. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:683-690. [PMID: 29225173 DOI: 10.1016/j.bbamem.2017.12.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 11/30/2017] [Accepted: 12/05/2017] [Indexed: 12/11/2022]
Abstract
Monotopic glycosyltransferases (GTs) interact with membranes via electrostatic interactions. The N-terminal domain is permanently anchored to the membrane while the membrane interaction of the C-terminal domain is believed to be weaker so that it undergoes a functionally relevant conformational change upon donor or acceptor binding. Here, we studied the applicability of this model to the glycosyltransferase WaaG. WaaG is involved in the synthesis of lipopolysaccharides (LPS) in Gram-negative bacteria and was previously categorized as a monotopic GT. We analyzed the binding of WaaG to membranes by stopped-flow fluorescence and NMR diffusion experiments. We find that electrostatic interactions are required to bind WaaG to membranes while mere hydrophobic interactions are not sufficient. WaaG senses the membrane's surface charge density but there is no preferential binding to specific anionic lipids. However, the binding is weaker than expected for monotopic GTs but similar to peripheral GTs. Therefore, WaaG may be a peripheral GT and this could be of functional relevance in vivo since LPS synthesis occurs only when WaaG is membrane-bound. We could not observe a C-terminal domain movement under our experimental conditions.
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Affiliation(s)
- Jobst Liebau
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Biao Fu
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Christian Brown
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Lena Mäler
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden.
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