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Pasin TM, Meneely KM, Ruiz DM, Lamb AL. A continuous fluorescence assay to measure nicotianamine synthase activity. Methods Enzymol 2024; 702:51-74. [PMID: 39155120 DOI: 10.1016/bs.mie.2024.06.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/20/2024]
Abstract
S-adenosylmethionine (SAM) is most widely known as the biological methylating agent of methyltransferases and for generation of radicals by the iron-sulfur dependent Radical SAM enzymes. SAM also serves as a substrate in biosynthetic reactions that harvest the aminobutyrate moiety of the methionine, producing methylthioadenosine as a co-product. These reactions are found in the production of polyamines such as spermine, siderophores derived from nicotianamine, and opine metallophores staphylopine and pseudopaline, among others. This procedure defines a highly sensitive, continuous fluorescence assay for the determination of steady state kinetic parameters for enzymes that generate the co-product methylthioadenosine.
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Affiliation(s)
- Thiago M Pasin
- Department of Chemistry, University of Texas at San Antonio, San Antonio, TX, United States
| | - Kathleen M Meneely
- Department of Chemistry, University of Texas at San Antonio, San Antonio, TX, United States
| | - Deegan M Ruiz
- Department of Chemistry, University of Texas at San Antonio, San Antonio, TX, United States
| | - Audrey L Lamb
- Department of Chemistry, University of Texas at San Antonio, San Antonio, TX, United States.
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Read BJ, Mitchell JBO, da Silva RG. Allosteric activation unveils protein-mass modulation of ATP phosphoribosyltransferase product release. Commun Chem 2024; 7:77. [PMID: 38582930 PMCID: PMC10998830 DOI: 10.1038/s42004-024-01165-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 03/28/2024] [Indexed: 04/08/2024] Open
Abstract
Heavy-isotope substitution into enzymes slows down bond vibrations and may alter transition-state barrier crossing probability if this is coupled to fast protein motions. ATP phosphoribosyltransferase from Acinetobacter baumannii is a multi-protein complex where the regulatory protein HisZ allosterically enhances catalysis by the catalytic protein HisGS. This is accompanied by a shift in rate-limiting step from chemistry to product release. Here we report that isotope-labelling of HisGS has no effect on the nonactivated reaction, which involves negative activation heat capacity, while HisZ-activated HisGS catalytic rate decreases in a strictly mass-dependent fashion across five different HisGS masses, at low temperatures. Surprisingly, the effect is not linked to the chemical step, but to fast motions governing product release in the activated enzyme. Disruption of a specific enzyme-product interaction abolishes the isotope effects. Results highlight how altered protein mass perturbs allosterically modulated thermal motions relevant to the catalytic cycle beyond the chemical step.
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Affiliation(s)
- Benjamin J Read
- School of Biology, Biomedical Sciences Research Complex, University of St Andrews, St Andrews, UK
| | - John B O Mitchell
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex, University of St Andrews, St Andrews, UK
| | - Rafael G da Silva
- School of Biology, Biomedical Sciences Research Complex, University of St Andrews, St Andrews, UK.
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Lachowicz JC, Lennox-Hvenekilde D, Myling-Petersen N, Salomonsen B, Verkleij G, Acevedo-Rocha CG, Caddell B, Gronenberg LS, Almo SC, Sommer MOA, Genee HJ, Grove TL. Discovery of a Biotin Synthase That Utilizes an Auxiliary 4Fe-5S Cluster for Sulfur Insertion. J Am Chem Soc 2024; 146:1860-1873. [PMID: 38215281 PMCID: PMC10813225 DOI: 10.1021/jacs.3c05481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Revised: 12/12/2023] [Accepted: 12/13/2023] [Indexed: 01/14/2024]
Abstract
Biotin synthase (BioB) is a member of the Radical SAM superfamily of enzymes that catalyzes the terminal step of biotin (vitamin B7) biosynthesis, in which it inserts a sulfur atom in desthiobiotin to form a thiolane ring. How BioB accomplishes this difficult reaction has been the subject of much controversy, mainly around the source of the sulfur atom. However, it is now widely accepted that the sulfur atom inserted to form biotin stems from the sacrifice of the auxiliary 2Fe-2S cluster of BioB. Here, we bioinformatically explore the diversity of BioBs available in sequence databases and find an unexpected variation in the coordination of the auxiliary iron-sulfur cluster. After in vitro characterization, including the determination of biotin formation and representative crystal structures, we report a new type of BioB utilized by virtually all obligate anaerobic organisms. Instead of a 2Fe-2S cluster, this novel type of BioB utilizes an auxiliary 4Fe-5S cluster. Interestingly, this auxiliary 4Fe-5S cluster contains a ligated sulfide that we propose is used for biotin formation. We have termed this novel type of BioB, Type II BioB, with the E. coli 2Fe-2S cluster sacrificial BioB representing Type I. This surprisingly ubiquitous Type II BioB has implications for our understanding of the function and evolution of Fe-S clusters in enzyme catalysis, highlighting the difference in strategies between the anaerobic and aerobic world.
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Affiliation(s)
- Jake C. Lachowicz
- Department
of Biochemistry, Albert Einstein College
of Medicine, Bronx, New York 10461, United States
| | - David Lennox-Hvenekilde
- The
Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kgs. Lyngby, 2800, Denmark
- Biosyntia
ApS, Copenhagen, 2100, Denmark
| | | | | | | | - Carlos G. Acevedo-Rocha
- The
Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kgs. Lyngby, 2800, Denmark
- Biosyntia
ApS, Copenhagen, 2100, Denmark
| | | | | | - Steven C. Almo
- Department
of Biochemistry, Albert Einstein College
of Medicine, Bronx, New York 10461, United States
| | - Morten O. A. Sommer
- The
Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kgs. Lyngby, 2800, Denmark
| | | | - Tyler L. Grove
- Department
of Biochemistry, Albert Einstein College
of Medicine, Bronx, New York 10461, United States
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Brown M, Schramm VL. Decreased Transition-State Analogue Affinity in Isotopically Heavy MTAN with Increased Catalysis. Biochemistry 2023; 62:2928-2933. [PMID: 37788145 PMCID: PMC10636763 DOI: 10.1021/acs.biochem.3c00434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
5'-Methylthioadenosine/S-adenosylhomocysteine nucleosidase from Helicobacter pylori (HpMTAN) demonstrated faster chemistry when expressed as an isotopically heavy protein, with 2H, 13C, and 15N replacing the bulk of normal isotopes. The inverse heavy enzyme isotope effect has been attributed to improved enzyme-reactant interactions causing more frequent transition-state formation ( Proc. Natl. Acad. Sci. U.S.A. 2021, 118, e2109118118). Transition-state analogues stabilize the transient dynamic geometry of the transition state and inform on transition-state dynamics. Here, a slow-onset, tight-binding transition-state analogue of HpMTAN is characterized with heavy and light enzymes. Dissociation constants for the initial encounter complex (Ki) and for the tightly bound complex after slow-onset inhibition (Ki*) with hexylthio-DADMe-Immucillin-A (HTDIA) gave Ki values for light and heavy HpMTAN = 52 ± 10 and 85 ± 13 pM and Ki* values = 5.9 ± 0.3 and 10.0 ± 1.2 pM, respectively. HTDIA dissociates from heavy HpMTAN at 0.063 ± 0.002 min-1, faster than that from light HpMTAN at 0.032 ± 0.004 min-1. These values are consistent with transition-state formation by an improved catalytic site dynamic search and inconsistent with catalytic efficiency proportional to tight binding of the transition state.
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Affiliation(s)
- Morais Brown
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Vern L Schramm
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
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Wagner AG, Eskandari R, Schramm VL. An enzyme-coupled microplate assay for activity and inhibition of hmdUMP hydrolysis by DNPH1. Anal Biochem 2023; 672:115171. [PMID: 37142196 PMCID: PMC10334339 DOI: 10.1016/j.ab.2023.115171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 04/19/2023] [Accepted: 04/25/2023] [Indexed: 05/06/2023]
Abstract
2'-Deoxynucleoside 5'-monophosphate N-glycosidase 1 (DNPH1) hydrolyzes the epigenetically modified nucleotide 5-hydroxymethyl 2'-deoxyuridine 5'-monophosphate (hmdUMP) derived from DNA metabolism. Published assays of DNPH1 activity are low throughput, use high concentrations of DNPH1, and have not incorporated or characterized reactivity with the natural substrate. We describe the enzymatic synthesis of hmdUMP from commercially available materials and define its steady-state kinetics with DNPH1 using a sensitive, two-pathway enzyme coupled assay. This continuous absorbance-based assay works in 96-well plate format using nearly 500-fold less DNPH1 than previous methods. With a Z prime value of 0.92, the assay is suitable for high-throughput assays, screening of DNPH1 inhibitors, or characterization of other deoxynucleotide monophosphate hydrolases.
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Affiliation(s)
- Andrew G Wagner
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, 10461, United States
| | - Roozbeh Eskandari
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, 10461, United States
| | - Vern L Schramm
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, 10461, United States.
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Abstract
This Perspective presents a review of our work and that of others in the highly controversial topic of the coupling of protein dynamics to reaction in enzymes. We have been involved in studying this topic for many years. Thus, this perspective will naturally present our own views, but it also is designed to present an overview of the variety of viewpoints of this topic, both experimental and theoretical. This is obviously a large and contentious topic.
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Affiliation(s)
- Steven D Schwartz
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
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Abstract
This Perspective reviews the use of Transition Path Sampling methods to study enzymatically catalyzed chemical reactions. First applied by our group to an enzymatic reaction over 15 years ago, the method has uncovered basic principles in enzymatic catalysis such as the protein promoting vibration, and it has also helped harmonize such ideas as electrostatic preorganization with dynamic views of enzyme function. It is now being used to help uncover principles of protein design necessary to artificial enzyme creation.
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Affiliation(s)
- Steven D Schwartz
- Department of Chemistry and Biochemistry University of Arizona Tucson, Arizona 85721, United States
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Antoniou D, Schwartz SD. Method for Identifying Common Features in Reactive Trajectories of a Transition Path Sampling Ensemble. J Chem Theory Comput 2022; 18:3997-4004. [PMID: 35536190 DOI: 10.1021/acs.jctc.2c00186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Simulation methods like transition path sampling (TPS) generate an abundance of information buried in the collection of reactive trajectories that they generate. However, only limited use has been made of this information, mainly for the identification of the reaction coordinate. The standard TPS tools have been designed for monitoring the progress of the system from reactants to products. However, the reaction coordinate does not contain all the information regarding the mechanism. In our earlier work, we have used TPS on enzymatic systems and have identified important motions in the reactant well that prepares the system for the reaction. Since these events take place in the reactant well, they are beyond the reach of standard TPS postprocessing methods. We present a simple scheme for identifying the common trends in enzymatic trajectories. This scheme was designed for a specific class of enzymatic reactions: it can be used for identifying motions that guide the system to reaction-ready conformations. We have applied it to two enzymatic systems that we have studied in the past, formate dehydrogenase and purine nucleoside phosphorylase, and we were able to identify interactions, far from the transition state, that are important for preparing the system for the reaction but that had been overlooked in earlier work.
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Affiliation(s)
- Dimitri Antoniou
- Department of Chemistry and Biochemistry, University of Arizona, 1306 East University Blvd., Tucson, Arizona 85721, United States
| | - Steven D Schwartz
- Department of Chemistry and Biochemistry, University of Arizona, 1306 East University Blvd., Tucson, Arizona 85721, United States
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