1
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Manrique PD, Leus IV, López CA, Mehla J, Malloci G, Gervasoni S, Vargiu AV, Kinthada RK, Herndon L, Hengartner NW, Walker JK, Rybenkov VV, Ruggerone P, Zgurskaya HI, Gnanakaran S. Predicting permeation of compounds across the outer membrane of P. aeruginosa using molecular descriptors. Commun Chem 2024; 7:84. [PMID: 38609430 PMCID: PMC11015012 DOI: 10.1038/s42004-024-01161-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 03/27/2024] [Indexed: 04/14/2024] Open
Abstract
The ability Gram-negative pathogens have at adapting and protecting themselves against antibiotics has increasingly become a public health threat. Data-driven models identifying molecular properties that correlate with outer membrane (OM) permeation and growth inhibition while avoiding efflux could guide the discovery of novel classes of antibiotics. Here we evaluate 174 molecular descriptors in 1260 antimicrobial compounds and study their correlations with antibacterial activity in Gram-negative Pseudomonas aeruginosa. The descriptors are derived from traditional approaches quantifying the compounds' intrinsic physicochemical properties, together with, bacterium-specific from ensemble docking of compounds targeting specific MexB binding pockets, and all-atom molecular dynamics simulations in different subregions of the OM model. Using these descriptors and the measured inhibitory concentrations, we design a statistical protocol to identify predictors of OM permeation/inhibition. We find consistent rules across most of our data highlighting the role of the interaction between the compounds and the OM. An implementation of the rules uncovered in our study is shown, and it demonstrates the accuracy of our approach in a set of previously unseen compounds. Our analysis sheds new light on the key properties drug candidates need to effectively permeate/inhibit P. aeruginosa, and opens the gate to similar data-driven studies in other Gram-negative pathogens.
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Affiliation(s)
- Pedro D Manrique
- Physics Department, George Washington University, Washington, 20052, DC, USA.
| | - Inga V Leus
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, 73019, OK, USA
| | - César A López
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, 87545, NM, USA
| | - Jitender Mehla
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, 73019, OK, USA
| | - Giuliano Malloci
- Department of Physics, University of Cagliari, Monserrato, 20052, CA, Italy
| | - Silvia Gervasoni
- Department of Physics, University of Cagliari, Monserrato, 20052, CA, Italy
| | - Attilio V Vargiu
- Department of Physics, University of Cagliari, Monserrato, 20052, CA, Italy
| | - Rama K Kinthada
- Department of Pharmacology and Physiology, Saint Louis University, St. Louis, 63103, MO, USA
| | - Liam Herndon
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, 87545, NM, USA
| | - Nicolas W Hengartner
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, 87545, NM, USA
| | - John K Walker
- Department of Pharmacology and Physiology, Saint Louis University, St. Louis, 63103, MO, USA
| | - Valentin V Rybenkov
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, 73019, OK, USA
| | - Paolo Ruggerone
- Department of Physics, University of Cagliari, Monserrato, 20052, CA, Italy
| | - Helen I Zgurskaya
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, 73019, OK, USA
| | - S Gnanakaran
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, 87545, NM, USA.
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2
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Gervasoni S, Mehla J, Bergen CR, Leus IV, Margiotta E, Malloci G, Bosin A, Vargiu AV, Lomovskaya O, Rybenkov VV, Ruggerone P, Zgurskaya HI. Molecular determinants of avoidance and inhibition of Pseudomonas aeruginosa MexB efflux pump. mBio 2023; 14:e0140323. [PMID: 37493633 PMCID: PMC10470492 DOI: 10.1128/mbio.01403-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 06/12/2023] [Indexed: 07/27/2023] Open
Abstract
Transporters of the resistance-nodulation-cell division (RND) superfamily of proteins are the dominant multidrug efflux power of Gram-negative bacteria. The major RND efflux pump of Pseudomonas aeruginosa is MexAB-OprM, in which the inner membrane transporter MexB is responsible for the recognition and binding of compounds. The high importance of this pump in clinical antibiotic resistance made it a subject of intense investigations and a promising target for the discovery of efflux pump inhibitors. This study is focused on a series of peptidomimetic compounds developed as effective inhibitors of MexAB-OprM. We performed multi-copy molecular dynamics simulations, machine-learning (ML) analyses, and site-directed mutagenesis of MexB to investigate interactions of MexB with representatives of efflux avoiders, substrates, and inhibitors. The analysis of both direct and water-mediated protein-ligand interactions revealed characteristic patterns for each class, highlighting significant differences between them. We found that efflux avoiders poorly interact with the access binding site of MexB, and inhibition engages amino acid residues that are not directly involved in binding and transport of substrates. In agreement, machine-learning models selected different residues predictive of MexB substrates and inhibitors. The differences in interactions were further validated by site-directed mutagenesis. We conclude that the substrate translocation and inhibition pathways of MexB split at the interface (between the main putative binding sites) and at the deep binding pocket and that interactions outside of the hydrophobic patch contribute to the inhibition of MexB. This molecular-level information could help in the rational design of new inhibitors and antibiotics less susceptible to the efflux mechanism. IMPORTANCE Multidrug transporters recognize and expel from cells a broad range of ligands including their own inhibitors. The difference between the substrate translocation and inhibition routes remains unclear. In this study, machine learning and computational and experimental approaches were used to understand dynamics of MexB interactions with its ligands. Our results show that some ligands engage a certain combination of polar and charged residues in MexB binding sites to be effectively expelled into the exit funnel, whereas others engage aromatic and hydrophobic residues that slow down or hinder the next step in the transporter cycle. These findings suggest that all MexB ligands fit into this substrate-inhibitor spectrum depending on their physico-chemical structures and properties.
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Affiliation(s)
- Silvia Gervasoni
- Department of Physics, University of Cagliari, Monserrato, Italy
| | - Jitender Mehla
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma, USA
| | - Charles R. Bergen
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma, USA
| | - Inga V. Leus
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma, USA
| | - Enrico Margiotta
- Department of Physics, University of Cagliari, Monserrato, Italy
| | - Giuliano Malloci
- Department of Physics, University of Cagliari, Monserrato, Italy
| | - Andrea Bosin
- Department of Physics, University of Cagliari, Monserrato, Italy
| | | | | | - Valentin V. Rybenkov
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma, USA
| | - Paolo Ruggerone
- Department of Physics, University of Cagliari, Monserrato, Italy
| | - Helen I. Zgurskaya
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma, USA
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3
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Stevens CM, Babii SO, Pandya AN, Li W, Li Y, Mehla J, Scott R, Hegde P, Prathipati PK, Acharya A, Liu J, Gumbart JC, North J, Jackson M, Zgurskaya HI. Proton transfer activity of the reconstituted Mycobacterium tuberculosis MmpL3 is modulated by substrate mimics and inhibitors. Proc Natl Acad Sci U S A 2022; 119:e2113963119. [PMID: 35858440 PMCID: PMC9335285 DOI: 10.1073/pnas.2113963119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 06/03/2022] [Indexed: 01/21/2023] Open
Abstract
Transporters belonging to the Resistance-Nodulation-cell Division (RND) superfamily of proteins such as Mycobacterium tuberculosis MmpL3 and its analogs are the focus of intense investigations due to their importance in the physiology of Corynebacterium-Mycobacterium-Nocardia species and antimycobacterial drug discovery. These transporters deliver trehalose monomycolates, the precursors of major lipids of the outer membrane, to the periplasm by a proton motive force-dependent mechanism. In this study, we successfully purified, from native membranes, the full-length and the C-terminal truncated M. tuberculosis MmpL3 and Corynebacterium glutamicum CmpL1 proteins and reconstituted them into proteoliposomes. We also generated a series of substrate mimics and inhibitors specific to these transporters, analyzed their activities in the reconstituted proteoliposomes, and carried out molecular dynamics simulations of the model MmpL3 transporter at different pH. We found that all reconstituted proteins facilitate proton translocation across a phospholipid bilayer, but MmpL3 and CmpL1 differ dramatically in their responses to pH and interactions with substrate mimics and indole-2-carboxamide inhibitors. Our results further suggest that some inhibitors abolish the transport activity of MmpL3 and CmpL1 by inhibition of proton translocation.
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Affiliation(s)
- Casey M. Stevens
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK 73019
| | - Svitlana O. Babii
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK 73019
| | - Amitkumar N. Pandya
- School of Pharmacy & Health Professions, Department of Pharmacy Sciences, Creighton University, Omaha, NE 68178
| | - Wei Li
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523
| | - Yupeng Li
- College of Chemistry, Jilin University, 130012 Changchun, China
- Tang Aoqing Honors Program in Science, Jilin University, 130012 Changchun, China
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332
| | - Jitender Mehla
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK 73019
| | - Robyn Scott
- School of Pharmacy & Health Professions, Department of Pharmacy Sciences, Creighton University, Omaha, NE 68178
| | - Pooja Hegde
- School of Pharmacy & Health Professions, Department of Pharmacy Sciences, Creighton University, Omaha, NE 68178
| | - Pavan K. Prathipati
- School of Pharmacy & Health Professions, Department of Pharmacy Sciences, Creighton University, Omaha, NE 68178
| | - Atanu Acharya
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332
| | - Jinchan Liu
- College of Chemistry, Jilin University, 130012 Changchun, China
- Tang Aoqing Honors Program in Science, Jilin University, 130012 Changchun, China
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332
| | - James C. Gumbart
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332
| | - Jeffrey North
- School of Pharmacy & Health Professions, Department of Pharmacy Sciences, Creighton University, Omaha, NE 68178
| | - Mary Jackson
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523
| | - Helen I. Zgurskaya
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK 73019
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Mehla J, Liechti G, Morgenstein RM, Caufield JH, Hosseinnia A, Gagarinova A, Phanse S, Goodacre N, Brockett M, Sakhawalkar N, Babu M, Xiao R, Montelione GT, Vorobiev S, den Blaauwen T, Hunt JF, Uetz P. ZapG (YhcB/DUF1043), a novel cell division protein in gamma-proteobacteria linking the Z-ring to septal peptidoglycan synthesis. J Biol Chem 2021; 296:100700. [PMID: 33895137 PMCID: PMC8163987 DOI: 10.1016/j.jbc.2021.100700] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 04/14/2021] [Accepted: 04/21/2021] [Indexed: 01/26/2023] Open
Abstract
YhcB, a poorly understood protein conserved across gamma-proteobacteria, contains a domain of unknown function (DUF1043) and an N-terminal transmembrane domain. Here, we used an integrated approach including X-ray crystallography, genetics, and molecular biology to investigate the function and structure of YhcB. The Escherichia coli yhcB KO strain does not grow at 45 °C and is hypersensitive to cell wall–acting antibiotics, even in the stationary phase. The deletion of yhcB leads to filamentation, abnormal FtsZ ring formation, and aberrant septum development. The Z-ring is essential for the positioning of the septa and the initiation of cell division. We found that YhcB interacts with proteins of the divisome (e.g., FtsI, FtsQ) and elongasome (e.g., RodZ, RodA). Seven of these interactions are also conserved in Yersinia pestis and/or Vibrio cholerae. Furthermore, we mapped the amino acid residues likely involved in the interactions of YhcB with FtsI and RodZ. The 2.8 Å crystal structure of the cytosolic domain of Haemophilus ducreyi YhcB shows a unique tetrameric α-helical coiled-coil structure likely to be involved in linking the Z-ring to the septal peptidoglycan-synthesizing complexes. In summary, YhcB is a conserved and conditionally essential protein that plays a role in cell division and consequently affects envelope biogenesis. Based on these findings, we propose to rename YhcB to ZapG (Z-ring-associated protein G). This study will serve as a starting point for future studies on this protein family and on how cells transit from exponential to stationary survival.
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Affiliation(s)
- Jitender Mehla
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, Virginia, USA.
| | - George Liechti
- Department of Microbiology and Immunology, Henry Jackson Foundation, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA
| | - Randy M Morgenstein
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma, USA
| | - J Harry Caufield
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Ali Hosseinnia
- Department of Biochemistry, Research and Innovation Centre, University of Regina, Regina, Saskatchewan, Canada
| | - Alla Gagarinova
- Department of Biochemistry, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Sadhna Phanse
- Department of Biochemistry, Research and Innovation Centre, University of Regina, Regina, Saskatchewan, Canada
| | - Norman Goodacre
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Mary Brockett
- Department of Microbiology and Immunology, Henry Jackson Foundation, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA
| | - Neha Sakhawalkar
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Mohan Babu
- Department of Biochemistry, Research and Innovation Centre, University of Regina, Regina, Saskatchewan, Canada
| | - Rong Xiao
- Nexomics Biosciences Inc., Rocky Hill, New Jersey, USA; Department of Chemistry and Chemical Biology, and Center for Biotechnology and Interdisciplinary Sciences, Rensselaer Polytechnic Institute, Troy, New York, USA
| | - Gaetano T Montelione
- Department of Chemistry and Chemical Biology, and Center for Biotechnology and Interdisciplinary Sciences, Rensselaer Polytechnic Institute, Troy, New York, USA; Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, Troy, New York, USA
| | - Sergey Vorobiev
- Department of Chemistry and Chemical Biology, and Center for Biotechnology and Interdisciplinary Sciences, Rensselaer Polytechnic Institute, Troy, New York, USA; Department of Biological Sciences, Columbia University, New York, New York, USA
| | - Tanneke den Blaauwen
- Bacterial Cell Biology & Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, Netherlands
| | - John F Hunt
- Department of Chemistry and Chemical Biology, and Center for Biotechnology and Interdisciplinary Sciences, Rensselaer Polytechnic Institute, Troy, New York, USA; Department of Biological Sciences, Columbia University, New York, New York, USA
| | - Peter Uetz
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, Virginia, USA.
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5
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Zhao S, Adamiak JW, Bonifay V, Mehla J, Zgurskaya HI, Tan DS. Defining new chemical space for drug penetration into Gram-negative bacteria. Nat Chem Biol 2020; 16:1293-1302. [PMID: 33199906 PMCID: PMC7897441 DOI: 10.1038/s41589-020-00674-6] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 09/11/2020] [Indexed: 12/24/2022]
Abstract
We live in the era of antibiotic resistance, and this problem will progressively worsen if no new solutions emerge. In particular, Gram-negative pathogens present both biological and chemical challenges that hinder the discovery of new antibacterial drugs. First, these bacteria are protected from a variety of structurally diverse drugs by a low-permeability barrier composed of two membranes with distinct permeability properties, in addition to active drug efflux, making this cell envelope impermeable to most compounds. Second, chemical libraries currently used in drug discovery contain few compounds that can penetrate Gram-negative bacteria. As a result of these challenges, intensive screening campaigns have led to few successes, highlighting the need for new approaches to identify regions of chemical space that are specifically relevant to antibacterial drug discovery. Herein we provide an overview of emerging insights into this problem and outline a general approach to addressing it using prospective analysis of chemical libraries for the ability of compounds to accumulate in Gram-negative bacteria. The overall goal is to develop robust cheminformatic tools to predict Gram-negative permeation and efflux, which can then be used to guide medicinal chemistry campaigns and the design of antibacterial discovery libraries.
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Affiliation(s)
- Shibin Zhao
- Chemical Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Justyna W Adamiak
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK, USA
| | - Vincent Bonifay
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK, USA
| | - Jitender Mehla
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK, USA
| | - Helen I Zgurskaya
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK, USA.
| | - Derek S Tan
- Chemical Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
- Tri-Institutional Research Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
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6
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Mansbach RA, Leus IV, Mehla J, Lopez CA, Walker JK, Rybenkov VV, Hengartner NW, Zgurskaya HI, Gnanakaran S. Machine Learning Algorithm Identifies an Antibiotic Vocabulary for Permeating Gram-Negative Bacteria. J Chem Inf Model 2020; 60:2838-2847. [PMID: 32453589 DOI: 10.1021/acs.jcim.0c00352] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Drug discovery faces a crisis. The industry has used up the "obvious" space in which to find novel drugs for biomedical applications, and productivity is declining. One strategy to combat this is rational approaches to expand the search space without relying on chemical intuition, to avoid rediscovery of similar spaces. In this work, we present proof of concept of an approach to rationally identify a "chemical vocabulary" related to a specific drug activity of interest without employing known rules. We focus on the pressing concern of multidrug resistance in Pseudomonas aeruginosa by searching for submolecules that promote compound entry into this bacterium. By synergizing theory, computation, and experiment, we validate our approach, explain the molecular mechanism behind identified fragments promoting compound entry, and select candidate compounds from an external library that display good permeation ability.
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Affiliation(s)
- Rachael A Mansbach
- Department of Theoretical Biology and Biophysics, Los Alamos National Lab, MS-K710, P.O. Box 1663, Los Alamos, New Mexico 87545-0001, United States
| | - Inga V Leus
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, SLSRC, Rm 1000, Norman, Oklahoma 73019-5251, United States
| | - Jitender Mehla
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, SLSRC, Rm 1000, Norman, Oklahoma 73019-5251, United States
| | - Cesar A Lopez
- Department of Theoretical Biology and Biophysics, Los Alamos National Lab, MS-K710, P.O. Box 1663, Los Alamos, New Mexico 87545-0001, United States
| | - John K Walker
- Pharmacology and Physiological Science, School of Medicine, Saint Louis University, Schwitalla Hall, Room M362, St. Louis, Missouri 63104, United States
| | - Valentin V Rybenkov
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, SLSRC, Rm 1000, Norman, Oklahoma 73019-5251, United States
| | - Nicolas W Hengartner
- Department of Theoretical Biology and Biophysics, Los Alamos National Lab, MS-K710, P.O. Box 1663, Los Alamos, New Mexico 87545-0001, United States
| | - Helen I Zgurskaya
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, SLSRC, Rm 1000, Norman, Oklahoma 73019-5251, United States
| | - S Gnanakaran
- Department of Theoretical Biology and Biophysics, Los Alamos National Lab, MS-K710, P.O. Box 1663, Los Alamos, New Mexico 87545-0001, United States
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7
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Rodionova IA, Zhang Z, Mehla J, Goodacre N, Babu M, Emili A, Uetz P, Saier MH. The phosphocarrier protein HPr of the bacterial phosphotransferase system globally regulates energy metabolism by directly interacting with multiple enzymes in Escherichia coli. J Biol Chem 2017. [PMID: 28634232 DOI: 10.1074/jbc.m117.795294] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The histidine-phosphorylatable phosphocarrier protein (HPr) is an essential component of the sugar-transporting phosphotransferase system (PTS) in many bacteria. Recent interactome findings suggested that HPr interacts with several carbohydrate-metabolizing enzymes, but whether HPr plays a regulatory role was unclear. Here, we provide evidence that HPr interacts with a large number of proteins in Escherichia coli We demonstrate HPr-dependent allosteric regulation of the activities of pyruvate kinase (PykF, but not PykA), phosphofructokinase (PfkB, but not PfkA), glucosamine-6-phosphate deaminase (NagB), and adenylate kinase (Adk). HPr is either phosphorylated on a histidyl residue (HPr-P) or non-phosphorylated (HPr). PykF is activated only by non-phosphorylated HPr, which decreases the PykF Khalf for phosphoenolpyruvate by 10-fold (from 3.5 to 0.36 mm), thus influencing glycolysis. PfkB activation by HPr, but not by HPr-P, resulted from a decrease in the Khalf for fructose-6-P, which likely influences both gluconeogenesis and glycolysis. Moreover, NagB activation by HPr was important for the utilization of amino sugars, and allosteric inhibition of Adk activity by HPr-P, but not by HPr, allows HPr to regulate the cellular energy charge coordinately with glycolysis. These observations suggest that HPr serves as a directly interacting global regulator of carbon and energy metabolism and probably of other physiological processes in enteric bacteria.
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Affiliation(s)
- Irina A Rodionova
- From the Department of Molecular Biology, Division of Biological Sciences, University of California at San Diego, La Jolla, California 92093-0116
| | - Zhongge Zhang
- From the Department of Molecular Biology, Division of Biological Sciences, University of California at San Diego, La Jolla, California 92093-0116
| | - Jitender Mehla
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, Virginia 23284
| | - Norman Goodacre
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, Virginia 23284
| | - Mohan Babu
- Department of Biochemistry, Research and Innovation Centre, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - Andrew Emili
- Donnelly Centre, University of Toronto, Toronto, Ontario M5S 3E1, Canada
| | - Peter Uetz
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, Virginia 23284
| | - Milton H Saier
- From the Department of Molecular Biology, Division of Biological Sciences, University of California at San Diego, La Jolla, California 92093-0116,.
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Abstract
Two-hybrid systems are one of the most popular, preferred, cost effective, and scalable in vivo genetic approaches for screening protein-protein interactions. A number of variants of yeast and bacterial two-hybrid systems exist, rendering them ideal for modern, flexible proteomics-driven studies. For mapping protein interactions at genome scales (that is, constructing an interactome), the yeast two-hybrid system has been extensively tested and is preferred over bacterial two-hybrid systems, given that users have created more resources such as a variety of vectors and other modifications. Each system has its own advantages and limitations and thus needs to be compared directly. For instance, the bacterial two-hybrid method seems a better fit than the yeast two-hybrid system to screen membrane-associated proteins. In this chapter, we provide detailed protocols for yeast and bacterial two-hybrid systems as well as a comparison of outcomes for each approach using our own and published data.
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Affiliation(s)
- J Mehla
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, VA, United States.
| | - J H Caufield
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, VA, United States
| | - N Sakhawalkar
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, VA, United States
| | - P Uetz
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, VA, United States.
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9
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Abstract
Virtually all processes in living cells are dependent on protein-protein interactions (PPIs). Understanding PPI networks is thus essential for molecular biology and disease research. One powerful genetic system for mapping PPIs both at a small scale and in a high-throughput manner is the yeast two-hybrid (Y2H) screen. In Y2H screening, PPIs are detected through the activation of reporter genes responding to a reconstituted transcription factor. In this introduction, we describe library- and array-based Y2H methods and explain their basic theory. We also include the rationale behind different Y2H approaches and strategies for optimizing results.
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Affiliation(s)
- Jitender Mehla
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, Virginia 23284
| | - J Harry Caufield
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, Virginia 23284
| | - Peter Uetz
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, Virginia 23284
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10
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Abstract
Yeast two-hybrid (Y2H) screens are an efficient system for mapping protein-protein interactions and whole interactomes. The screens can be performed using random libraries or collections of defined open reading frames (ORFs) called ORFeomes. This protocol describes both library and array-based Y2H screening, with an emphasis on array-based assays. Array-based Y2H is commonly used to test a number of "prey" proteins for interactions with a single "bait" (target) protein or pool of proteins. The advantage of this approach is the direct identification of interacting protein pairs without further downstream experiments: The identity of the preys is known and does not require further confirmation. In contrast, constructing and screening a random prey library requires identification of individual prey clones and systematic retesting. Retesting is typically performed in an array format.
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Affiliation(s)
- Jitender Mehla
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, Virginia 23284
| | - J Harry Caufield
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, Virginia 23284
| | - Peter Uetz
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, Virginia 23284
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11
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Mehla J, Ernst R, Moore R, Wakschlag A, Marquis MK, Ambudkar SV, Golin J. Evidence for a molecular diode-based mechanism in a multispecific ATP-binding cassette (ABC) exporter: SER-1368 as a gatekeeping residue in the yeast multidrug transporter Pdr5. J Biol Chem 2014; 289:26597-26606. [PMID: 25112867 DOI: 10.1074/jbc.m114.586032] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
ATP-binding cassette multidrug efflux pumps transport a wide range of substrates. Current models suggest that a drug binds relatively tightly to a transport site in the transmembrane domains when the protein is in the closed inward facing conformation. Upon binding of ATP, the transporter can switch to an outward facing (drug off or drug releasing) structure of lower affinity. ATP hydrolysis is critically important for remodeling the drug-binding site to facilitate drug release and to reset the transporter for a new transport cycle. We characterized the novel phenotype of an S1368A mutant that lies in the putative drug-binding pocket of the yeast multidrug transporter Pdr5. This substitution created broad, severe drug hypersensitivity, although drug binding, ATP hydrolysis, and intradomain signaling were indistinguishable from the wild-type control. Several different rhodamine 6G efflux and accumulation assays yielded evidence consistent with the possibility that Ser-1368 prevents reentry of the excluded drug.
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Affiliation(s)
- Jitender Mehla
- Department of Biology, Catholic University of America, Washington, D. C. 20064
| | - Robert Ernst
- Institute of Biochemistry, Biocenter of the Goethe University, Frankfurt, Germany 60438, and
| | - Rachel Moore
- Department of Biology, Catholic University of America, Washington, D. C. 20064
| | - Adina Wakschlag
- Department of Biology, Catholic University of America, Washington, D. C. 20064
| | - Mary Kate Marquis
- Department of Biology, Catholic University of America, Washington, D. C. 20064
| | - Suresh V Ambudkar
- Laboratory of Cell Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892
| | - John Golin
- Department of Biology, Catholic University of America, Washington, D. C. 20064,.
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Furman C, Mehla J, Ananthaswamy N, Arya N, Kulesh B, Kovach I, Ambudkar SV, Golin J. The deviant ATP-binding site of the multidrug efflux pump Pdr5 plays an active role in the transport cycle. J Biol Chem 2013; 288:30420-30431. [PMID: 24019526 DOI: 10.1074/jbc.m113.494682] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pdr5 is the founding member of a large subfamily of evolutionarily distinct, clinically important fungal ABC transporters containing a characteristic, deviant ATP-binding site with altered Walker A, Walker B, Signature (C-loop), and Q-loop residues. In contrast to these motifs, the D-loops of the two ATP-binding sites have similar sequences, including a completely conserved aspartate residue. Alanine substitution mutants in the deviant Walker A and Signature motifs retain significant, albeit reduced, ATPase activity and drug resistance. The D-loop residue mutants D340A and D1042A showed a striking reduction in plasma membrane transporter levels. The D1042N mutation localized properly had nearly WT ATPase activity but was defective in transport and was profoundly hypersensitive to Pdr5 substrates. Therefore, there was a strong uncoupling of ATPase activity and drug efflux. Taken together, the properties of the mutants suggest an additional, critical intradomain signaling role for deviant ATP-binding sites.
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Affiliation(s)
| | | | | | | | | | | | - Suresh V Ambudkar
- Laboratory of Cell Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892; Chemistry, Catholic University of America, Washington, D. C. 20064
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Mehla J, Sood SK. Connecting membrane fluidity and surface charge to pore-forming antimicrobial peptides resistance by an ANN-based predictive model. Appl Microbiol Biotechnol 2012; 97:4377-84. [DOI: 10.1007/s00253-012-4289-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Revised: 07/03/2012] [Accepted: 07/07/2012] [Indexed: 11/25/2022]
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Mehla J, Sood SK. Substantiation in Enterococcus faecalis of dose-dependent resistance and cross-resistance to pore-forming antimicrobial peptides by use of a polydiacetylene-based colorimetric assay. Appl Environ Microbiol 2011; 77:786-93. [PMID: 21115699 PMCID: PMC3028714 DOI: 10.1128/aem.01496-10] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Accepted: 11/15/2010] [Indexed: 11/20/2022] Open
Abstract
A better understanding of the antimicrobial peptide (AMP) resistance mechanisms of bacteria will facilitate the design of effective and potent AMPs. Therefore, to understand resistance mechanisms and for in vitro assessment, variants of Enterococcus faecalis that are resistant to different doses of the fungal AMP alamethicin (Alm(r)) were selected and characterized. The resistance developed was dose dependent, as both doses of alamethicin and degrees of resistance were colinear. The formation of bacterial cell aggregates observed in resistant cells may be the prime mechanism of resistance because overall, a smaller cell surface in aggregated cells is exposed to AMPs. Increased rigidity of the membranes of Alm(r) variants, because of their altered fatty acids, was correlated with limited membrane penetration by alamethicin. Thus, resistance developed against alamethicin was an adaptation of the bacterial cells through changes in their morphological features and physiological activity and the composition of membrane phospholipids. The Alm(r) variants showed cross-resistance to pediocin, which indicated that resistance developed against both AMPs may share a mechanism, i.e., an alteration in the cell membrane. High percentages of colorimetric response by both AMPs against polydiacetylene/lipid biomimetic membranes of Alm(r) variants confirmed that altered phospholipid and fatty acid compositions were responsible for acquisition of resistance. So far, this is the only report of quantification of resistance and cross-resistance using an in vitro colorimetric approach. Our results imply that a single AMP or AMP analog may be effective against bacterial strains having a common mechanism of resistance. Therefore, an understanding of resistance would contribute to the development of a single efficient, potent AMP against resistant strains that share a mechanism of resistance.
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Affiliation(s)
- Jitender Mehla
- Animal Biochemistry Division, National Dairy Research Institute, Karnal-132001, Haryana, India.
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Mehla J, Sood S. Resistance Developed Against Alamethicin an Antimicrobial Peptide in Enterococcus faecalis is Directly Proportional to its Concentration. Antiviral Res 2009. [DOI: 10.1016/j.antiviral.2009.02.157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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