1
|
An Y, Sedinkin SL, Venditti V. Solution NMR methods for structural and thermodynamic investigation of nanoparticle adsorption equilibria. NANOSCALE ADVANCES 2022; 4:2583-2607. [PMID: 35769933 PMCID: PMC9195484 DOI: 10.1039/d2na00099g] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Accepted: 05/07/2022] [Indexed: 05/09/2023]
Abstract
Characterization of dynamic processes occurring at the nanoparticle (NP) surface is crucial for developing new and more efficient NP catalysts and materials. Thus, a vast amount of research has been dedicated to developing techniques to characterize sorption equilibria. Over recent years, solution NMR spectroscopy has emerged as a preferred tool for investigating ligand-NP interactions. Indeed, due to its ability to probe exchange dynamics over a wide range of timescales with atomic resolution, solution NMR can provide structural, kinetic, and thermodynamic information on sorption equilibria involving multiple adsorbed species and intermediate states. In this contribution, we review solution NMR methods for characterizing ligand-NP interactions, and provide examples of practical applications using these methods as standalone techniques. In addition, we illustrate how the integrated analysis of several NMR datasets was employed to elucidate the role played by support-substrate interactions in mediating the phenol hydrogenation reaction catalyzed by ceria-supported Pd nanoparticles.
Collapse
Affiliation(s)
- Yeongseo An
- Department of Chemistry, Iowa State University Hach Hall, 2438 Pammel Drive Ames Iowa 50011 USA +1-515-294-7550 +1-515-294-1044
| | - Sergey L Sedinkin
- Department of Chemistry, Iowa State University Hach Hall, 2438 Pammel Drive Ames Iowa 50011 USA +1-515-294-7550 +1-515-294-1044
| | - Vincenzo Venditti
- Department of Chemistry, Iowa State University Hach Hall, 2438 Pammel Drive Ames Iowa 50011 USA +1-515-294-7550 +1-515-294-1044
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University Ames Iowa 50011 USA
| |
Collapse
|
2
|
Purslow JA, Nguyen TT, Khatiwada B, Singh A, Venditti V. N 6-methyladenosine binding induces a metal-centered rearrangement that activates the human RNA demethylase Alkbh5. SCIENCE ADVANCES 2021; 7:7/34/eabi8215. [PMID: 34407931 PMCID: PMC8373141 DOI: 10.1126/sciadv.abi8215] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 06/29/2021] [Indexed: 05/13/2023]
Abstract
Alkbh5 catalyzes demethylation of the N 6-methyladenosine (m6A), an epigenetic mark that controls several physiological processes including carcinogenesis and stem cell differentiation. The activity of Alkbh5 comprises two coupled reactions. The first reaction involves decarboxylation of α-ketoglutarate (αKG) and formation of a Fe4+═O species. This oxyferryl intermediate oxidizes the m6A to reestablish the canonical base. Despite coupling between the two reactions being required for the correct Alkbh5 functioning, the mechanisms linking dioxygen activation to m6A binding are not fully understood. Here, we use solution NMR to investigate the structure and dynamics of apo and holo Alkbh5. We show that binding of m6A to Alkbh5 induces a metal-centered rearrangement of αKG that increases the exposed area of the metal, making it available for binding O2 Our study reveals the molecular mechanisms underlying activation of Alkbh5, therefore opening new perspectives for the design of novel strategies to control gene expression and cancer progression.
Collapse
Affiliation(s)
| | - Trang T Nguyen
- Department of Chemistry, Iowa State University, Ames, IA 50011, USA
| | | | - Aayushi Singh
- Department of Chemistry, Iowa State University, Ames, IA 50011, USA
| | - Vincenzo Venditti
- Department of Chemistry, Iowa State University, Ames, IA 50011, USA.
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011, USA
| |
Collapse
|
3
|
Purslow JA, Thimmesch JN, Sivo V, Nguyen TT, Khatiwada B, Dotas RR, Venditti V. A Single Point Mutation Controls the Rate of Interconversion Between the g + and g - Rotamers of the Histidine 189 χ2 Angle That Activates Bacterial Enzyme I for Catalysis. Front Mol Biosci 2021; 8:699203. [PMID: 34307459 PMCID: PMC8295985 DOI: 10.3389/fmolb.2021.699203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 06/29/2021] [Indexed: 11/13/2022] Open
Abstract
Enzyme I (EI) of the bacterial phosphotransferase system (PTS) is a master regulator of bacterial metabolism and a promising target for development of a new class of broad-spectrum antibiotics. The catalytic activity of EI is mediated by several intradomain, interdomain, and intersubunit conformational equilibria. Therefore, in addition to its relevance as a drug target, EI is also a good model for investigating the dynamics/function relationship in multidomain, oligomeric proteins. Here, we use solution NMR and protein design to investigate how the conformational dynamics occurring within the N-terminal domain (EIN) affect the activity of EI. We show that the rotameric g+-to-g− transition of the active site residue His189 χ2 angle is decoupled from the state A-to-state B transition that describes a ∼90° rigid-body rearrangement of the EIN subdomains upon transition of the full-length enzyme to its catalytically competent closed form. In addition, we engineered EIN constructs with modulated conformational dynamics by hybridizing EIN from mesophilic and thermophilic species, and used these chimeras to assess the effect of increased or decreased active site flexibility on the enzymatic activity of EI. Our results indicate that the rate of the autophosphorylation reaction catalyzed by EI is independent from the kinetics of the g+-to-g− rotameric transition that exposes the phosphorylation site on EIN to the incoming phosphoryl group. In addition, our work provides an example of how engineering of hybrid mesophilic/thermophilic chimeras can assist investigations of the dynamics/function relationship in proteins, therefore opening new possibilities in biophysics.
Collapse
Affiliation(s)
- Jeffrey A Purslow
- Department of Chemistry, Iowa State University, Ames, IA, United States
| | | | - Valeria Sivo
- Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, Università Degli Studi Della Campania, Caserta, Italy
| | - Trang T Nguyen
- Department of Chemistry, Iowa State University, Ames, IA, United States
| | | | - Rochelle R Dotas
- Department of Chemistry, Iowa State University, Ames, IA, United States
| | - Vincenzo Venditti
- Department of Chemistry, Iowa State University, Ames, IA, United States.,Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA, United States
| |
Collapse
|
4
|
Structure elucidation of the elusive Enzyme I monomer reveals the molecular mechanisms linking oligomerization and enzymatic activity. Proc Natl Acad Sci U S A 2021; 118:2100298118. [PMID: 33975952 DOI: 10.1073/pnas.2100298118] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Enzyme I (EI) is a phosphotransferase enzyme responsible for converting phosphoenolpyruvate (PEP) into pyruvate. This reaction initiates a five-step phosphorylation cascade in the bacterial phosphotransferase (PTS) transduction pathway. Under physiological conditions, EI exists in an equilibrium between a functional dimer and an inactive monomer. The monomer-dimer equilibrium is a crucial factor regulating EI activity and the phosphorylation state of the overall PTS. Experimental studies of EI's monomeric state have yet been hampered by the dimer's high thermodynamic stability, which prevents its characterization by standard structural techniques. In this study, we modified the dimerization domain of EI (EIC) by mutating three amino acids involved in the formation of intersubunit salt bridges. The engineered variant forms an active dimer in solution that can bind and hydrolyze PEP. Using hydrostatic pressure as an additional perturbation, we were then able to study the complete dissociation of the variant from 1 bar to 2.5 kbar in the absence and the presence of EI natural ligands. Backbone residual dipolar couplings collected under high-pressure conditions allowed us to determine the conformational ensemble of the isolated EIC monomeric state in solution. Our calculations reveal that three catalytic loops near the dimerization interface become unstructured upon monomerization, preventing the monomeric enzyme from binding its natural substrate. This study provides an atomic-level characterization of EI's monomeric state and highlights the role of the catalytic loops as allosteric connectors controlling both the activity and oligomerization of the enzyme.
Collapse
|