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Sun L, Hristova K, Bondar AN, Wimley WC. Structural Determinants of Peptide Nanopore Formation. ACS NANO 2024; 18:15831-15844. [PMID: 38844421 PMCID: PMC11191747 DOI: 10.1021/acsnano.4c02824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 05/15/2024] [Accepted: 05/23/2024] [Indexed: 06/19/2024]
Abstract
We have evolved the nanopore-forming macrolittin peptides from the bee venom peptide melittin using successive generations of synthetic molecular evolution. Despite their sequence similarity to the broadly membrane permeabilizing cytolytic melittin, the macrolittins have potent membrane selectivity. They form nanopores in synthetic bilayers made from 1-palmitoyl, 2-oleoyl-phosphatidylcholine (POPC) at extremely low peptide concentrations and yet have essentially no cytolytic activity against any cell membrane, even at high concentration. Here, we explore the structural determinants of macrolittin nanopore stability in POPC bilayers using atomistic molecular dynamics simulations and experiments on macrolittins and single-site variants. Simulations of macrolittin nanopores in POPC bilayers show that they are stabilized by an extensive, cooperative hydrogen bond network comprised of the many charged and polar side chains interacting with each other via bridges of water molecules and lipid headgroups. Lipid molecules with unusual conformations participate in the H-bond network and are an integral part of the nanopore structure. To explore the role of this H-bond network on membrane selectivity, we swapped three critical polar residues with the nonpolar residues found in melittin. All variants have potency, membrane selectivity, and cytotoxicity that were intermediate between a cytotoxic melittin variant called MelP5 and the macrolittins. Simulations showed that the variants had less organized H-bond networks of waters and lipids with unusual structures. The membrane-spanning, cooperative H-bond network is a critical determinant of macrolittin nanopore stability and membrane selectivity. The results described here will help guide the future design and optimization of peptide nanopore-based applications.
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Affiliation(s)
- Leisheng Sun
- Department
of Biochemistry and Molecular Biology, Tulane
University School of Medicine, New Orleans, Louisiana 70112, United States
| | - Kalina Hristova
- Department
of Materials Science and Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, Maryland 21218, United States
- Institute
for NanoBioTechnology, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Ana-Nicoleta Bondar
- Faculty
of Physics, University of Bucharest, Atomiştilor 405, Măgurele 077125, Romania
- Forschungszentrum
Jülich, Institute of Computational
Biomedicine, IAS-5/INM-9,
Wilhelm-Johnen Straße, 5428 Jülich, Germany
| | - William C. Wimley
- Department
of Biochemistry and Molecular Biology, Tulane
University School of Medicine, New Orleans, Louisiana 70112, United States
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Noguchi T. Mechanism of Proton Transfer through the D1-E65/D2-E312 Gate during Photosynthetic Water Oxidation. J Phys Chem B 2024; 128:1866-1875. [PMID: 38364371 DOI: 10.1021/acs.jpcb.3c07787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2024]
Abstract
In photosystem II, the D1-E65/D2-E312 dyad in the Cl-1 channel has been proposed to play a pivotal role in proton transfer during water oxidation. However, the precise mechanism remains elusive. Here, the proton transfer mechanism within the Cl-1 channel was investigated using quantum mechanics/molecular mechanics calculations. The molecular vibration of the E65/E312 dyad and its deuteration effect revealed that the recently suggested stepwise proton transfer, i.e., initial proton release from the dyad followed by slow reprotonation, does not occur in the Cl-1 channel. Instead, proton transfer is proposed to take place via a conformational change at the E65/E312 dyad, acting as a gate. In its closed form, a proton is trapped within the dyad, preventing forward proton transfer. This closed form converts into the open form, where protonated D1-E65 provides a hydrogen bond to the water network, thereby facilitating fast Grotthuss-type proton transfer.
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Affiliation(s)
- Takumi Noguchi
- Department of Physics, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
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3
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Kapur B, Baldessari F, Lazaratos M, Nar H, Schnapp G, Giorgetti A, Bondar AN. Protons taken hostage: Dynamic H-bond networks of the pH-sensing GPR68. Comput Struct Biotechnol J 2023; 21:4370-4384. [PMID: 37711190 PMCID: PMC10498176 DOI: 10.1016/j.csbj.2023.08.034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 08/30/2023] [Accepted: 08/30/2023] [Indexed: 09/16/2023] Open
Abstract
Proton-sensing G Protein Coupled Receptors (GPCRs) sense changes in the extracellular pH to effect cell signaling for cellular homeostasis. They tend to be overexpressed in solid tumors associated with acidic extracellular pH, and are of direct interest as drug targets. How proton-sensing GPCRs sense extracellular acidification and activate upon protonation change is important to understand, because it may guide the design of therapeutics. Lack of publicly available experimental structures make it challenging to discriminate between conflicting mechanisms proposed for proton-binding, as main roles have been assigned to either an extracellular histidine cluster or to an internal carboxylic triad. Here we present a protocol to derive and evaluate structural models of the proton-sensing GPR68. This approach integrates state-of-the-art homology modeling with microsecond-timescale atomistic simulations, and with a detailed assessment of the compatibility of the structural models with known structural features of class A GPCRs. To decipher structural elements of potential interest for protonation-coupled conformational changes of GPR68, we used the best-compatible model as a starting point for independent atomistic simulations of GPR68 with different protonation states, and graph computations to characterize the response of GPR68 to changes in protonation. We found that GPR68 hosts an extended hydrogen-bond network that inter-connects the extracellular histidine cluster to the internal carboxylic triad, and which can even reach groups at the cytoplasmic G-protein binding site. Taken together, results suggest that GPR68 relies on dynamic, hydrogen-bond networks to inter-connect extracellular and internal proton-binding sites, and to elicit conformational changes at the cytoplasmic G-protein binding site.
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Affiliation(s)
- Bhav Kapur
- Boehringer-Ingelheim Pharma GmbH & Co. KG, Birkendorfer Straße 65, 88397 Biberach an der Riß, Germany
- Christian-Albrechts-University of Kiel, 24118 Kiel, Germany
| | | | - Michalis Lazaratos
- Department of Physics, Theoretical Molecular Biophysics Group, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
| | - Herbert Nar
- Boehringer-Ingelheim Pharma GmbH & Co. KG, Birkendorfer Straße 65, 88397 Biberach an der Riß, Germany
| | - Gisela Schnapp
- Boehringer-Ingelheim Pharma GmbH & Co. KG, Birkendorfer Straße 65, 88397 Biberach an der Riß, Germany
| | - Alejandro Giorgetti
- University of Verona, Department of Biotechnology, 37134 Verona, Italy
- Forschungszentrum Jülich, Institute for Neuroscience and Medicine and Institute for Advanced Simulations (IAS-5/INM-9), Computational Biomedicine, Wilhelm-Johnen Straße, 52525 Jülich, Germany
| | - Ana-Nicoleta Bondar
- Forschungszentrum Jülich, Institute for Neuroscience and Medicine and Institute for Advanced Simulations (IAS-5/INM-9), Computational Biomedicine, Wilhelm-Johnen Straße, 52525 Jülich, Germany
- University of Bucharest, Faculty of Physics, Str. Atomiştilor 405, 077125 Bucharest-Măgurele, Romania
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Lešnik S, Bren U, Domratcheva T, Bondar AN. Fentanyl and the Fluorinated Fentanyl Derivative NFEPP Elicit Distinct Hydrogen-Bond Dynamics of the Opioid Receptor. J Chem Inf Model 2023; 63:4732-4748. [PMID: 37498626 DOI: 10.1021/acs.jcim.3c00197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2023]
Abstract
The development of safe therapeutics to manage pain is of central interest for biomedical applications. The fluorinated fentanyl derivative N-(3-fluoro-1-phenethylpiperidin-4-yl)-N-phenylpropionamide (NFEPP) is potentially a safer alternative to fentanyl because unlike fentanyl─which binds to the μ-opioid receptor (MOR) at both physiological and acidic pH─NFEPP might bind to the MOR only at acidic pH typical of inflamed tissue. Knowledge of the protonation-coupled dynamics of the receptor-drug interactions is thus required to understand the molecular mechanism by which receptor activation initiates cell signaling to silence pain. To this end, here we have carried out extensive atomistic simulations of the MOR in different protonation states, in the absence of opioid drugs, and in the presence of fentanyl vs NFEPP. We used graph-based analyses to characterize internal hydrogen-bond networks that could contribute to the activation of the MOR. We find that fentanyl and NFEPP prefer distinct binding poses and that, in their binding poses, fentanyl and NFEPP partake in distinct internal hydrogen-bond networks, leading to the cytoplasmic G-protein-binding region. Moreover, the protonation state of functionally important aspartic and histidine side chains impacts hydrogen-bond networks that extend throughout the receptor, such that the ligand-bound MOR presents at its cytoplasmic G-protein-binding side, a hydrogen-bonding environment where dynamics depend on whether fentanyl or NFEPP is bound, and on the protonation state of specific MOR groups. The exquisite sensitivity of the internal protein-water hydrogen-bond network to the protonation state and to details of the drug binding could enable the MOR to elicit distinct pH- and opioid-dependent responses at its cytoplasmic G-protein-binding site.
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Affiliation(s)
- Samo Lešnik
- Faculty of Chemistry and Chemical Engineering, Laboratory of Physical Chemistry and Chemical Thermodynamics, University of Maribor, Smetanova ulica 17, SI-2000 Maribor, Slovenia
- Institute for Environmental Protection and Sensors, Beloruska ulica 7, 2000 Maribor, Slovenia
| | - Urban Bren
- Faculty of Chemistry and Chemical Engineering, Laboratory of Physical Chemistry and Chemical Thermodynamics, University of Maribor, Smetanova ulica 17, SI-2000 Maribor, Slovenia
- Institute for Environmental Protection and Sensors, Beloruska ulica 7, 2000 Maribor, Slovenia
- Faculty of Mathematics, Natural Sciences and Information Technologies, University of Primorska, SI-6000 Koper, Slovenia
| | - Tatiana Domratcheva
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia
- Department of Biomolecular Mechanisms, Max-Plank-Institute fur Medizinische Forschung, D-69120 Heidelberg, Germany
| | - Ana-Nicoleta Bondar
- Faculty of Physics, University of Bucharest, Atomiştilor 405, 077125 Măgurele, Romania
- Institute of Computational Biomedicine, IAS-5/INM-9, Forschungszentrum Jülich, Wilhelm-Johnen Straße, 5428 Jülich, Germany
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Bondar AN, Barboiu M. Protons at bio-interfaces. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184139. [PMID: 36775006 DOI: 10.1016/j.bbamem.2023.184139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 02/06/2023] [Indexed: 02/12/2023]
Affiliation(s)
- Ana-Nicoleta Bondar
- University of Bucharest, Faculty of Physics, Atomiștilor 405, Măgurele 077125, Romania; Forschungszentrum Jülich, Institute of Computational Biomedicine, IAS-5/INM-9, Wilhelm-Johnen Straße, 5428 Jülich, Germany.
| | - Mihail Barboiu
- Université de Montpelier, Institut Europeen de Membranes, Adaptive Supramolecular Nanosystems Group, ENSCM-CNRS, Place E. Bataillon CC047, 34095 Motpellier, France.
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