scholarly journals X-ray crystallography reveals molecular recognition mechanism for sugar binding in a melibiose transporter MelB

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Lan Guan ◽  
Parameswaran Hariharan
Keyword(s):  
Molecular Recognition ◽  
Binding Pocket ◽  
Cation Binding ◽  
Recognition Mechanism ◽  
X Ray ◽  
X Ray Crystallography ◽  
Sugar Binding ◽  
Sugar Specificity ◽  
Major Facilitator ◽  
Mfs Transporters

AbstractMajor facilitator superfamily_2 transporters are widely found from bacteria to mammals. The melibiose transporter MelB, which catalyzes melibiose symport with either Na+, Li+, or H+, is a prototype of the Na+-coupled MFS transporters, but its sugar recognition mechanism has been a long-unsolved puzzle. Two high-resolution X-ray crystal structures of a Salmonella typhimurium MelB mutant with a bound ligand, either nitrophenyl-α-d-galactoside or dodecyl-β-d-melibioside, were refined to a resolution of 3.05 or 3.15 Å, respectively. In the substrate-binding site, the interaction of both galactosyl moieties on the two ligands with MelBSt are virturally same, so the sugar specificity determinant pocket can be recognized, and hence the molecular recognition mechanism for sugar binding in MelB has been deciphered. The conserved cation-binding pocket is also proposed, which directly connects to the sugar specificity pocket. These key structural findings have laid a solid foundation for our understanding of the cooperative binding and symport mechanisms in Na+-coupled MFS transporters, including eukaryotic transporters such as MFSD2A.

scholarly journals Function, Structure, and Evolution of the Major Facilitator Superfamily: The LacY Manifesto

2014 ◽  
Vol 2014 ◽  
pp. 1-20 ◽  
Author(s):  
M. Gregor Madej
Keyword(s):  
Structural Information ◽  
Large Body ◽  
Major Facilitator Superfamily ◽  
Lactose Permease ◽  
Test Bed ◽  
X Ray ◽  
X Ray Crystallography ◽  
Major Facilitator ◽  
Mfs Transporters ◽  
Alternating Access

The major facilitator superfamily (MFS) is a diverse group of secondary transporters with members found in all kingdoms of life. A paradigm for MFS is the lactose permease (LacY) of Escherichia coli, which couples the stoichiometric translocation of a galactopyranoside and an H+ across the cytoplasmic membrane. LacY has been the test bed for the development of many methods applied for the analysis of transport proteins. X-ray structures of an inward-facing conformation and the most recent structure of an almost occluded conformation confirm many conclusions from previous studies. Although structure models are critical, they are insufficient to explain the catalysis of transport. The clues to understanding transport are based on the principles of enzyme kinetics. Secondary transport is a dynamic process—static snapshots of X-ray crystallography describe it only partially. However, without structural information, the underlying chemistry is virtually impossible to conclude. A large body of biochemical/biophysical data derived from systematic studies of site-directed mutants in LacY suggests residues critically involved in the catalysis, and a working model for the symport mechanism that involves alternating access of the binding site is presented. The general concepts derived from the bacterial LacY are examined for their relevance to other MFS transporters.

scholarly journals Molecular recognition of sugar binding in a melibiose transporter MelB by X-ray crystallography

2020 ◽  
Author(s):  
Lan Guan ◽  
Parameswaran Hariharan
Keyword(s):  
Molecular Recognition ◽  
Binding Site ◽  
Crystal Structures ◽  
Mammalian Cells ◽  
Substrate Binding ◽  
Structural Basis ◽  
Cooperative Binding ◽  
Recognition Mechanism ◽  
Substrate Binding Site ◽  
X Ray

AbstractThe symporter melibiose permease MelB is the best-studied representative from MFS_2 family and the only protein in this large family with crystal structure determined. Previous thermodynamic studies show that MelB utilizes a cooperative binding as the core mechanism for its obligatory symport. Here we present two sugar-bound X-ray crystal structures of a Salmonella typhimurium MelB D59C uniport mutant that binds and catalyzes melibiose transport uncoupled to either cation, as determined by biochemical and biophysical characterizations. The two structures with bound nitrophenyl-α-D-galactoside or dodecyl-β-D-melibioside, which were refined to a resolution of 3.05 or 3.15 Å, respectively, are virtually identical at an outward-facing conformation; each one contains a α-galactoside molecule in the middle of protein. In the substrate-binding site, the galactosyl moiety on both ligands are at an essentially same configuration, so a galactoside specificity determinant pocket can be recognized, and hence the molecular recognition mechanism for the binding of sugar in MelB is deciphered. The data also allow to assign the conserved cation-binding pocket, which is directly connected to the sugar specificity determinant pocket. The intimate connection between the two selection sites lays the structural basis for the cooperative binding and coupled transport. This key structural finding answered the long-standing question on the substrate binding for the Na+-coupled MFS family of transporters.SignificanceMajor facilitator superfamily_2 transporters contain >10,000 members that are widely expressed from bacteria to mammalian cells, and catalyze uptake of varied nutrients from sugars to phospholipids. While several crystal structures with bound sugar for other MFS permeases have been determined, they are either uniporters or symporters coupled solely to H+. MelB catalyzes melibiose symport with either Na+, Li+, or H+, a prototype for Na+-coupled MFS transporters, but its sugar recognition has been a long-unsolved puzzle. Two high-resolution crystal structures presented here clearly reveal the molecular recognition mechanism for the binding of sugar in MelB. The substrate-binding site is characterized with a small specificity groove adjoining a large nonspecific cavity, which could offer a potential for future exploration of active transporters for drug delivery.

scholarly journals UHR PX and NPC studies of H-FABP water network with tiny perdeuterated crystals

2014 ◽  
Vol 70 (a1) ◽  
pp. C1200-C1200
Author(s):  
Alberto Podjarny ◽  
Matthew Blakeley ◽  
Michael Haertlein ◽  
Andre Mitschler ◽  
Alexandra Cousido-Siah ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Charge Distribution ◽  
Binding Pocket ◽  
Internal Cavity ◽  
Water Molecules ◽  
Fatty Acid Binding ◽  
X Ray ◽  
X Ray Crystallography ◽  
Internal Water ◽  
Dynamics Simulations

We have obtained very detailed information about the internal water molecules in the large internal cavity inside fatty acid binding (FABP) proteins , in the presence of bound fatty acids (FA), by Ultra High Resolution X-Ray Crystallography (UHR) to 0.7 Å and Neutron Protein Crystallography (NPC) to 1.9 Å using a "radically small" (V=0.05 mm3) crystal. These waters form a very well ordered dense cluster of 12 molecules, positioned between the hydrophilic internal wall of the cavity and the fatty acid molecule. This information has been used for a detailed electrostatic analysis based on the charge distribution description modeled in the multipole formalism and on the Atoms in Molecules theory. This information is also being used in molecular dynamics simulations of H-FABP and its complex with FA in order to quantify the energetic contribution of these internal waters to the binding energy. The experiment has been done with oleic acid, coming with the protein expressed in E. Coli. The results have been analyzed in order to understand the interactions between the FA, the internal water and the protein, and in particular the role played by the water molecules in determining the potency and specificity of FA binding to FABPs. The major tool for visualizing the water molecules inside the H-FABP cavity is UHR X-Ray Crystallography combined with NPC. UHR crystallographic structures give the positions of hydrogen and oxygen atoms for well-ordered water molecules. NPC determines hydrogen atom positions, particularly of water molecules which have multiple conformations, leading to the best possible crystallographic model. This model was then complemented by a transferred charge distribution to accurately determine the electrostatic and topological properties in the binding pocket, providing a description of the way water molecules in hydration layer contribute to the binding of ligand, which is essential to understand and model ligand binding.

scholarly journals Which Properties Allow Ligands to Open and Bind to the Transient Binding Pocket of Human Aldose Reductase?

Biomolecules ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1837
Author(s):  
Anna Sandner ◽  
Khang Ngo ◽  
Christoph P. Sager ◽  
Frithjof Scheer ◽  
Michael Daude ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Charge Distribution ◽  
Aldose Reductase ◽  
Binding Pocket ◽  
Crystallographic Data ◽  
X Ray ◽  
X Ray Crystallography ◽  
Ph Values ◽  
Selective Ligands ◽  
Binding Position

The transient specificity pocket of aldose reductase only opens in response to specific ligands. This pocket may offer an advantage for the development of novel, more selective ligands for proteins with similar topology that lack such an adaptive pocket. Our aim was to elucidate which properties allow an inhibitor to bind in the specificity pocket. A series of inhibitors that share the same parent scaffold but differ in their attached aromatic substituents were screened using ITC and X-ray crystallography for their ability to occupy the pocket. Additionally, we investigated the electrostatic potentials and charge distribution across the attached terminal aromatic groups with respect to their potential to bind to the transient pocket of the enzyme using ESP calculations. These methods allowed us to confirm the previously established hypothesis that an electron-deficient aromatic group is an important prerequisite for opening and occupying the specificity pocket. We also demonstrated from our crystal structures that a pH shift between 5 and 8 does not affect the binding position of the ligand in the specificity pocket. This allows for a comparison between thermodynamic and crystallographic data collected at different pH values.

Metabolic intervention targeting 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) using a structure-based design.

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. e13518-e13518
Author(s):  
Lars Ährlund-Richter ◽  
Katarina Färnegårdh ◽  
Elisee Wiita ◽  
Mattias Jönsson ◽  
Carina Norström ◽  
...  
Keyword(s):  
Cell Growth ◽  
High Throughput ◽  
High Throughput Screening ◽  
Structural Information ◽  
Human Cancer ◽  
Isothermal Calorimetry ◽  
Binding Pocket ◽  
Binding Modes ◽  
X Ray ◽  
X Ray Crystallography

e13518 Background: By producing fructose-2,6-bisphosphate, PFKFB3 functions as an activator of anaerobic glycolysis. PFKFB3 is both over expressed and over activated in many of the types of human cancer. Specific inhibition of the PFKFB3 enzyme results in a reduction in metabolism and cell growth in oxygen-deficient cancer environments. Methods: High-throughput screening. Medicinal Chemistry. Structure-Based Drug Design, X-ray Crystallography. NMR. Isothermal Calorimetry. Dynamic Light Scatttering. ADME. Results: A high-throughput screening of 50.000 selected compounds, by means of a biochemical assay, generated 105 hits including both ATP-and non-ATP competitive hits as identified by NMR binding experiments. The latter type was prioritized and two hits with a similar “ring-linker-ring structure” were selected for further expansions. Interestingly, although structurally similar, the two hits were found by means of X-ray crystallography to exhibit different binding modes within the fructose pocket. Based on their respective binding mode, two chemical series were developed displaying different ADME properties and PFKFB isoenzyme selectivity. Calorimetry verified a reversible strong enthalpy driven, direct binding for both chemical series. A third chemical series was developed towards yet another unoccupied binding pocket within the fructose-site, yielding a 5-fold increase in potency. Strong interactions within the new pocket were confirmed using X-ray crystallography. Our PFKFB3 inhibitors were shown to reduce tumor cell growth in vitro and to exhibit combinatory effects with Cisplatin. Conclusions: We have targeted the fructose-binding pocket of PFKFB3, developed compounds with nM binding potency and have gained a detailed understanding of SAR via structural information. The structure-based analysis has provided a good understanding of the molecular interactions, which is important for further biological/clinical positioning: e.g., combination with chemotherapy, optimization of PK properties and proof of principle in vivo.

Substrate-recognition mechanism of tomato β-galactosidase 4 using X-ray crystallography and docking simulation

Planta ◽  
2020 ◽  
Vol 252 (4) ◽  
Author(s):  
Kaori Matsuyama ◽  
Tatsuya Kondo ◽  
Kiyohiko Igarashi ◽  
Tatsuji Sakamoto ◽  
Megumi Ishimaru
Keyword(s):  
Substrate Recognition ◽  
Docking Simulation ◽  
Recognition Mechanism ◽  
X Ray ◽  
X Ray Crystallography

scholarly journals Elucidation of Molecular Mechanism of a Selective PPARα Modulator, Pemafibrate, through Combinational Approaches of X-ray Crystallography, Thermodynamic Analysis, and First-Principle Calculations

2020 ◽  
Vol 21 (1) ◽  
pp. 361 ◽  
Author(s):  
Mayu Kawasaki ◽  
Akira Kambe ◽  
Yuta Yamamoto ◽  
Sundaram Arulmozhiraja ◽  
Sohei Ito ◽  
...  
Keyword(s):  
Ligand Binding ◽  
Molecular Mechanism ◽  
Structural Changes ◽  
Molecular Level ◽  
Hydrophobic Interactions ◽  
Binding Pocket ◽  
Titration Calorimetry ◽  
X Ray ◽  
X Ray Crystallography ◽  
Steroid Receptor Coactivator

The selective PPARα modulator (SPPARMα) is expected to medicate dyslipidemia with minimizing adverse effects. Recently, pemafibrate was screened from the ligand library as an SPPARMα bearing strong potency. Several clinical pieces of evidence have proved the usefulness of pemafibrate as a medication; however, how pemafibrate works as a SPPARMα at the molecular level is not fully known. In this study, we investigate the molecular mechanism behind its novel SPPARMα character through a combination of approaches of X-ray crystallography, isothermal titration calorimetry (ITC), and fragment molecular orbital (FMO) analysis. ITC measurements have indicated that pemafibrate binds more strongly to PPARα than to PPARγ. The crystal structure of PPARα-ligand binding domain (LBD)/pemafibrate/steroid receptor coactivator-1 peptide (SRC1) determined at 3.2 Å resolution indicates that pemafibrate binds to the ligand binding pocket (LBP) of PPARα in a Y-shaped form. The structure also reveals that the conformation of the phenoxyalkyl group in pemafibrate is flexible in the absence of SRC1 coactivator peptide bound to PPARα; this gives a freedom for the phenoxyalkyl group to adopt structural changes induced by the binding of coactivators. FMO calculations have indicated that the accumulation of hydrophobic interactions provided by the residues at the LBP improve the interaction between pemafibrate and PPARα compared with the interaction between fenofibrate and PPARα.

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