1
|
Lagunes L, Briggs K, Martin-Holder P, Xu Z, Maurer D, Ghabra K, Deeds EJ. Modeling reveals the strength of weak interactions in stacked-ring assembly. Biophys J 2024:S0006-3495(24)00329-1. [PMID: 38762753 DOI: 10.1016/j.bpj.2024.05.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 04/30/2024] [Accepted: 05/15/2024] [Indexed: 05/20/2024] Open
Abstract
Cells employ many large macromolecular machines for the execution and regulation of processes that are vital for cell and organismal viability. Interestingly, cells cannot synthesize these machines as functioning units. Instead, cells synthesize the molecular parts that must then assemble into the functional complex. Many important machines, including chaperones such as GroEL and proteases such as the proteasome, comprise protein rings that are stacked on top of one another. While there is some experimental data regarding how stacked-ring complexes such as the proteasome self-assemble, a comprehensive understanding of the dynamics of stacked-ring assembly is currently lacking. Here, we developed a mathematical model of stacked-trimer assembly and performed an analysis of the assembly of the stacked homomeric trimer, which is the simplest stacked-ring architecture. We found that stacked rings are particularly susceptible to a form of kinetic trapping that we term "deadlock," in which the system gets stuck in a state where there are many large intermediates that are not the fully assembled structure but that cannot productively react. When interaction affinities are uniformly strong, deadlock severely limits assembly yield. We thus predicted that stacked rings would avoid situations where all interfaces in the structure have high affinity. Analysis of available crystal structures indicated that indeed the majority-if not all-of stacked trimers do not contain uniformly strong interactions. Finally, to better understand the origins of deadlock, we developed a formal pathway analysis and showed that, when all the binding affinities are strong, many of the possible pathways are utilized. In contrast, optimal assembly strategies utilize only a small number of pathways. Our work suggests that deadlock is a critical factor influencing the evolution of macromolecular machines and provides general principles for understanding the self-assembly efficiency of existing machines.
Collapse
Affiliation(s)
- Leonila Lagunes
- Department of Integrative Biology and Physiology, UCLA, Los Angeles, California; Institute for Quantitative and Computational Biosciences, UCLA, Los Angeles, California
| | - Koan Briggs
- Department of Physics, University of Kansas, Lawrence, Kansas
| | - Paige Martin-Holder
- Department of Molecular Immunology, Microbiology and Genetics, UCLA, Los Angeles, California
| | - Zaikun Xu
- Center for Computational Biology, University of Kansas, Lawrence, Kansas
| | - Dustin Maurer
- Center for Computational Biology, University of Kansas, Lawrence, Kansas
| | - Karim Ghabra
- Computational and Systems Biology IDP, UCLA, Los Angeles, California
| | - Eric J Deeds
- Department of Integrative Biology and Physiology, UCLA, Los Angeles, California; Institute for Quantitative and Computational Biosciences, UCLA, Los Angeles, California; Center for Computational Biology, University of Kansas, Lawrence, Kansas.
| |
Collapse
|
2
|
Jayasinghe-Arachchige VM, Serafim LF, Hu Q, Ozen C, Moorkkannur SN, Schenk G, Prabhakar R. Elucidating the Roles of Distinct Chemical Factors in the Hydrolytic Activities of Hetero- and Homonuclear Synthetic Analogues of Binuclear Metalloenzymes. ACS Catal 2023. [DOI: 10.1021/acscatal.2c05758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Affiliation(s)
| | - Leonardo F. Serafim
- Department of Chemistry, University of Miami, Coral Gables, Florida 33146, United States
| | - Qiaoyu Hu
- Department of Chemistry, University of Miami, Coral Gables, Florida 33146, United States
| | - Cihan Ozen
- Department of Chemistry, University of Miami, Coral Gables, Florida 33146, United States
| | - Sreerag N. Moorkkannur
- Department of Chemistry, University of Miami, Coral Gables, Florida 33146, United States
| | - Gerhard Schenk
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Brisbane, Queensland 4072, Australia
| | - Rajeev Prabhakar
- Department of Chemistry, University of Miami, Coral Gables, Florida 33146, United States
| |
Collapse
|
3
|
Solovjeva ON. New Role of Water in Transketolase Catalysis. Int J Mol Sci 2023; 24:ijms24032068. [PMID: 36768400 PMCID: PMC9917271 DOI: 10.3390/ijms24032068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Revised: 01/13/2023] [Accepted: 01/16/2023] [Indexed: 01/21/2023] Open
Abstract
Transketolase catalyzes the interconversion of keto and aldo sugars. Its coenzyme is thiamine diphosphate. The binding of keto sugar with thiamine diphosphate is possible only after C2 deprotonation of its thiazole ring. It is believed that deprotonation occurs due to the direct transfer of a proton to the amino group of its aminopyrimidine ring. Using mass spectrometry, it is shown that a water molecule is directly involved in the deprotonation process. After the binding of thiamine diphosphate with transketolase and its subsequent cleavage, a thiamine diphosphate molecule is formed with a mass increased by one oxygen molecule. After fragmentation, a thiamine diphosphate molecule is formed with a mass reduced by one and two hydrogen atoms, that is, HO and H2O are split off. Based on these data, it is assumed that after the formation of holotransketolase, water is covalently bound to thiamine diphosphate, and carbanion is formed as a result of its elimination. This may be a common mechanism for other thiamine enzymes. The participation of a water molecule in the catalysis of the one-substrate transketolase reaction and a possible reason for the effect of the acceptor substrate on the affinity of the donor substrate for active sites are also shown.
Collapse
Affiliation(s)
- Olga N Solovjeva
- Belozersky Institute of Physico-Chemical Biology, Moscow State University, 119234 Moscow, Russia
| |
Collapse
|
4
|
Substrate binding mechanism of glycerophosphodiesterase towards organophosphate pesticides. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.115526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
5
|
Selleck C, Pedroso MM, Wilson L, Krco S, Knaven EG, Miraula M, Mitić N, Larrabee JA, Brück T, Clark A, Guddat LW, Schenk G. Structure and mechanism of potent bifunctional β-lactam- and homoserine lactone-degrading enzymes from marine microorganisms. Sci Rep 2020; 10:12882. [PMID: 32732933 PMCID: PMC7392888 DOI: 10.1038/s41598-020-68612-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 06/26/2020] [Indexed: 11/11/2022] Open
Abstract
Genes that confer antibiotic resistance can rapidly be disseminated from one microorganism to another by mobile genetic elements, thus transferring resistance to previously susceptible bacterial strains. The misuse of antibiotics in health care and agriculture has provided a powerful evolutionary pressure to accelerate the spread of resistance genes, including those encoding β-lactamases. These are enzymes that are highly efficient in inactivating most of the commonly used β-lactam antibiotics. However, genes that confer antibiotic resistance are not only associated with pathogenic microorganisms, but are also found in non-pathogenic (i.e. environmental) microorganisms. Two recent examples are metal-dependent β-lactamases (MBLs) from the marine organisms Novosphingobium pentaromativorans and Simiduia agarivorans. Previous studies have demonstrated that their β-lactamase activity is comparable to those of well-known MBLs from pathogenic sources (e.g. NDM-1, AIM-1) but that they also possess efficient lactonase activity, an activity associated with quorum sensing. Here, we probed the structure and mechanism of these two enzymes using crystallographic, spectroscopic and fast kinetics techniques. Despite highly conserved active sites both enzymes demonstrate significant variations in their reaction mechanisms, highlighting both the extraordinary ability of MBLs to adapt to changing environmental conditions and the rather promiscuous acceptance of diverse substrates by these enzymes.
Collapse
Affiliation(s)
- Christopher Selleck
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD, 4072, Australia
| | - Marcelo Monteiro Pedroso
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD, 4072, Australia. .,Australian Centre for Ecogenomics, The University of Queensland, St. Lucia, QLD, 4072, Australia. .,Sustainable Minerals Institute, The University of Queensland, St. Lucia, QLD, 4072, Australia.
| | - Liam Wilson
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD, 4072, Australia
| | - Stefan Krco
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD, 4072, Australia
| | - Esmée Gianna Knaven
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD, 4072, Australia
| | - Manfredi Miraula
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD, 4072, Australia.,Department of Chemistry, Maynooth University, Maynooth, County Kildare, Ireland
| | - Nataša Mitić
- Department of Chemistry, Maynooth University, Maynooth, County Kildare, Ireland
| | - James A Larrabee
- Department of Chemistry and Biochemistry, Middlebury College, Middlebury, VT, 05753, USA
| | - Thomas Brück
- Werner Siemens Chair of Synthetic Biotechnology, Department of Chemistry, Technical University of Munich (TUM), Lichtenberg Str. 4, 85748, Garching, Germany
| | - Alice Clark
- Sustainable Minerals Institute, The University of Queensland, St. Lucia, QLD, 4072, Australia
| | - Luke W Guddat
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD, 4072, Australia
| | - Gerhard Schenk
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD, 4072, Australia. .,Australian Centre for Ecogenomics, The University of Queensland, St. Lucia, QLD, 4072, Australia. .,Sustainable Minerals Institute, The University of Queensland, St. Lucia, QLD, 4072, Australia.
| |
Collapse
|
6
|
Sharma G, Jayasinghe-Arachchige VM, Hu Q, Schenk G, Prabhakar R. Effect of Chemically Distinct Substrates on the Mechanism and Reactivity of a Highly Promiscuous Metallohydrolase. ACS Catal 2020. [DOI: 10.1021/acscatal.9b04847] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Gaurav Sharma
- Department of Chemistry, University of Miami, Coral Gables, Florida 33146, United States
| | | | - Qiaoyu Hu
- Department of Chemistry, University of Miami, Coral Gables, Florida 33146, United States
| | - Gerhard Schenk
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Rajeev Prabhakar
- Department of Chemistry, University of Miami, Coral Gables, Florida 33146, United States
| |
Collapse
|
7
|
Hu Q, Jayasinghe‐Arachchige VM, Sharma G, Serafim LF, Paul TJ, Prabhakar R. Mechanisms of peptide and phosphoester hydrolysis catalyzed by two promiscuous metalloenzymes (insulin degrading enzyme and glycerophosphodiesterase) and their synthetic analogues. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2020. [DOI: 10.1002/wcms.1466] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Qiaoyu Hu
- Department of Chemistry, University of Miami Coral Gables Florida
| | | | - Gaurav Sharma
- Department of Chemistry, University of Miami Coral Gables Florida
| | | | - Thomas J. Paul
- Department of Chemistry, University of Miami Coral Gables Florida
| | - Rajeev Prabhakar
- Department of Chemistry, University of Miami Coral Gables Florida
| |
Collapse
|
8
|
Singh A, Raj P, Singh A, Dubowski JJ, Kaur N, Singh N. Metal-Organocatalyst for Detoxification of Phosphorothioate Pesticides: Demonstration of Acetylcholine Esterase Activity. Inorg Chem 2019; 58:9773-9784. [PMID: 31318533 DOI: 10.1021/acs.inorgchem.9b00770] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In recent years, transition metal complexes have been developed for catalytical degradation of a phosphate ester bond, particularly in RNA and DNA; however, less consideration has been given for development of complexes for the degradation of a phosphorothioate bond, as they are the foremost used pesticides in the environment and are toxic to human beings. In this context, we have developed copper complexes of benzimidazolium based ligands for catalytical degradation of a series of organophosphates (parathion, paraoxon, methyl-parathion) at ambient conditions. The copper complexes (assigned as N1-N3) were characterized using single X-ray crystallography which revealed that all three complexes are mononuclear and distorted square planner in geometry. Further, the solution state studies of the prepared complexes were carried out using UV-visible absorption, fluorescence spectroscopy, and cyclic voltametry. The complexes N1 and N2 have benzimidazolium ionic liquid as base attached with two 2-mercapto-benzimidazole pods, whereas complex N3 contains a nonionic ligand. The synthesized copper complexes were evaluated for their catalytic activity for degradation of organophosphates. It is interesting that the complex containing the ionic ligand efficiently degrades phosphorothioate pesticides, whereas complex N3 was not found to be appropriate for degradation due to a weaker conversion rate. The organophosphate degradation studies were monitored by recording absorbance spectra of parathion in the presence of catalyst, i.e., copper complexes with respect to time. The parathion was hydrolyzed into para-nitrophenol and diethyl thiophosphate. Moreover, to analyze the inhibition activity of the pesticides toward acetylcholine esterase enzyme in the presence of prepared metal complexes, Ellman's assay was performed and revealed that, within 20 min, the inhibition of acetylcholine esterase enzyme decreases by up to 13%.
Collapse
Affiliation(s)
- Amanpreet Singh
- Department of Chemistry , Indian Institute of Technology Ropar , Punjab 140001 , India
| | - Pushap Raj
- Department of Chemistry , Indian Institute of Technology Ropar , Punjab 140001 , India
| | - Ajnesh Singh
- Department of Applied Sciences and Humanities , Jawaharlal Nehru Govt. Engineering College , Sundernagar , Mandi (H.P.) , 175018 , India
| | - Jan J Dubowski
- Laboratory for Quantum Semiconductors and Photo-based Biotechnology, Interdisciplinary Institute for Technological Innovation (3IT), CNRS UMI-3463, Department of Electrical and Computer Engineering , Universite de Sherbrooke , 3000 Boulevard de l'Université , Sherbrooke , QC J1K 0A5 , Canada
| | - Navneet Kaur
- Department of Chemistry , Panjab University , Chandigarh , 160014 , India
| | - Narinder Singh
- Department of Chemistry , Indian Institute of Technology Ropar , Punjab 140001 , India
| |
Collapse
|
9
|
Hu Q, Jayasinghe-Arachchige VM, Zuchniarz J, Prabhakar R. Effects of the Metal Ion on the Mechanism of Phosphodiester Hydrolysis Catalyzed by Metal-Cyclen Complexes. Front Chem 2019; 7:195. [PMID: 31024887 PMCID: PMC6460053 DOI: 10.3389/fchem.2019.00195] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 03/14/2019] [Indexed: 12/01/2022] Open
Abstract
In this study, mechanisms of phosphodiester hydrolysis catalyzed by six di- and tetravalent metal-cyclen (M-C) complexes (Zn-C, Cu-C, Co-C, Ce-C, Zr-C and Ti-C) have been investigated using DFT calculations. The activities of these complexes were studied using three distinct mechanisms: (1) direct attack ( DA ), (2) catalyst-assisted ( CA ), and (3) water-assisted ( WA ). All divalent metal complexes (Zn-C, Cu-C and Co-C) coordinated to the BNPP substrate in a monodentate fashion and activated its scissile phosphoester bond. However, all tetravalent metal complexes (Ce-C, Zr-C, and Ti-C) interacted with BNPP in a bidentate manner and strengthened this bond. The DA mechanism was energetically the most feasible for all divalent M-C complexes, while the WA mechanism was favored by the tetravalent complexes, except Ce-C. The divalent complexes were found to be more reactive than their tetravalent counterparts. Zn-C catalyzed the hydrolysis with the lowest barrier among all M-C complexes, while Ti-C was the most reactive tetravalent complex. The activities of Ce-C and Zr-C, except Ti-C, were improved with an increase in the coordination number of the metal ion. The structural and mechanistic information provided in this study will be very helpful in the development of more efficient metal complexes for this critical reaction.
Collapse
Affiliation(s)
| | | | | | - Rajeev Prabhakar
- Department of Chemistry, University of Miami, Coral Gables, FL, United States
| |
Collapse
|
10
|
Sharma G, Hu Q, Jayasinghe-Arachchige VM, Paul TJ, Schenk G, Prabhakar R. Investigating coordination flexibility of glycerophosphodiesterase (GpdQ) through interactions with mono-, di-, and triphosphoester (NPP, BNPP, GPE, and paraoxon) substrates. Phys Chem Chem Phys 2019; 21:5499-5509. [DOI: 10.1039/c8cp07031h] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Interactions of the catalytically active binuclear form of glycerophosphodiesterase (GpdQ) with chemically diverse substrates, i.e. phosphomono-, phosphodi-, and phosphotriester have been investigated using molecular dynamics (MD) simulations.
Collapse
Affiliation(s)
- Gaurav Sharma
- Department of Chemistry
- University of Miami
- Coral Gables
- USA
| | - Qiaoyu Hu
- Department of Chemistry
- University of Miami
- Coral Gables
- USA
| | | | - Thomas J. Paul
- Department of Chemistry
- University of Miami
- Coral Gables
- USA
| | - Gerhard Schenk
- School of Chemistry and Molecular Biosciences
- The University of Queensland
- St. Lucia
- Australia
| | | |
Collapse
|
11
|
van Loo B, Bayer CD, Fischer G, Jonas S, Valkov E, Mohamed MF, Vorobieva A, Dutruel C, Hyvönen M, Hollfelder F. Balancing Specificity and Promiscuity in Enzyme Evolution: Multidimensional Activity Transitions in the Alkaline Phosphatase Superfamily. J Am Chem Soc 2018; 141:370-387. [PMID: 30497259 DOI: 10.1021/jacs.8b10290] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Highly proficient, promiscuous enzymes can be springboards for functional evolution, able to avoid loss of function during adaptation by their capacity to promote multiple reactions. We employ a systematic comparative study of structure, sequence, and substrate specificity to track the evolution of specificity and reactivity between promiscuous members of clades of the alkaline phosphatase (AP) superfamily. Construction of a phylogenetic tree of protein sequences maps out the likely transition zone between arylsulfatases (ASs) and phosphonate monoester hydrolases (PMHs). Kinetic analysis shows that all enzymes characterized have four chemically distinct phospho- and sulfoesterase activities, with rate accelerations ranging from 1011- to 1017-fold for their primary and 109- to 1012-fold for their promiscuous reactions, suggesting that catalytic promiscuity is widespread in the AP-superfamily. This functional characterization and crystallography reveal a novel class of ASs that is so similar in sequence to known PMHs that it had not been recognized as having diverged in function. Based on analysis of snapshots of catalytic promiscuity "in transition", we develop possible models that would allow functional evolution and determine scenarios for trade-off between multiple activities. For the new ASs, we observe largely invariant substrate specificity that would facilitate the transition from ASs to PMHs via trade-off-free molecular exaptation, that is, evolution without initial loss of primary activity and specificity toward the original substrate. This ability to bypass low activity generalists provides a molecular solution to avoid adaptive conflict.
Collapse
Affiliation(s)
- Bert van Loo
- Department of Biochemistry , University of Cambridge , Cambridge CB2 1GA , United Kingdom
| | - Christopher D Bayer
- Department of Biochemistry , University of Cambridge , Cambridge CB2 1GA , United Kingdom
| | - Gerhard Fischer
- Department of Biochemistry , University of Cambridge , Cambridge CB2 1GA , United Kingdom
| | - Stefanie Jonas
- Department of Biochemistry , University of Cambridge , Cambridge CB2 1GA , United Kingdom
| | - Eugene Valkov
- Department of Biochemistry , University of Cambridge , Cambridge CB2 1GA , United Kingdom
| | - Mark F Mohamed
- Department of Biochemistry , University of Cambridge , Cambridge CB2 1GA , United Kingdom
| | - Anastassia Vorobieva
- Department of Biochemistry , University of Cambridge , Cambridge CB2 1GA , United Kingdom
| | - Celine Dutruel
- Department of Biochemistry , University of Cambridge , Cambridge CB2 1GA , United Kingdom
| | - Marko Hyvönen
- Department of Biochemistry , University of Cambridge , Cambridge CB2 1GA , United Kingdom
| | - Florian Hollfelder
- Department of Biochemistry , University of Cambridge , Cambridge CB2 1GA , United Kingdom
| |
Collapse
|
12
|
Monteiro Pedroso M, Selleck C, Bilyj J, Harmer JR, Gahan LR, Mitić N, Standish AJ, Tierney DL, Larrabee JA, Schenk G. Reaction mechanism of the metallohydrolase CpsB from Streptococcus pneumoniae, a promising target for novel antimicrobial agents. Dalton Trans 2018; 46:13194-13201. [PMID: 28573276 DOI: 10.1039/c7dt01350g] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
CpsB is a metal ion-dependent hydrolase involved in the biosynthesis of capsular polysaccharides in bacterial organisms. The enzyme has been proposed as a promising target for novel chemotherapeutics to combat antibiotic resistance. The crystal structure of CpsB indicated the presence of as many as three closely spaced metal ions, modelled as Mn2+, in the active site. While the preferred metal ion composition in vivo is obscure Mn2+ and Co2+ have been demonstrated to be most effective in reconstituting activity. Using isothermal titration calorimetry (ITC) we have demonstrated that, in contrast to the crystal structure, only two Mn2+ or Co2+ ions bind to a monomer of CpsB. This observation is in agreement with magnetic circular dichroism (MCD) and electron paramagnetic resonance (EPR) data that indicate the presence of two weakly ferromagnetically coupled Co2+ ions in the active site of catalytically active CpsB. While CpsB is known to be a phosphoesterase we have also been able to demonstrate that this enzyme is efficient in hydrolyzing the β-lactam substrate nitrocefin. Steady-state and stopped-flow kinetics measurements further indicated that phosphoesters and nitrocefin undergo catalysis in a conserved manner with a metal ion-bridging hydroxide acting as a nucleophile. Thus, the combined physicochemical studies demonstrate that CpsB is a novel member of the dinuclear metallohydrolase family.
Collapse
Affiliation(s)
- Marcelo Monteiro Pedroso
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Queensland 4072, Australia.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Invergo AM, Liu S, Dicken RD, Mouat AR, Delferro M, Lohr TL, Marks TJ. How Close Is Too Close? Polymerization Behavior and Monomer-Dependent Reorganization of a Bimetallic Salphen Organotitanium Catalyst. Organometallics 2018. [DOI: 10.1021/acs.organomet.8b00220] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Anna M. Invergo
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Shaofeng Liu
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Rachel D. Dicken
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Aidan R. Mouat
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Massimiliano Delferro
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Tracy L. Lohr
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Tobin J. Marks
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| |
Collapse
|
14
|
Chagas MA, Pereira ES, Godinho MPB, Da Silva JCS, Rocha WR. Base Mechanism to the Hydrolysis of Phosphate Triester Promoted by the Cd2+/Cd2+ Active site of Phosphotriesterase: A Computational Study. Inorg Chem 2018; 57:5888-5902. [DOI: 10.1021/acs.inorgchem.8b00361] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Marcelo A. Chagas
- LQC-MM: Laboratório de Química Computacional e Modelagem Molecular Departamento de Química, ICEx, Universidade Federal de Minas Gerais 31270-901 Pampulha, Belo Horizonte, Minas Gerais, Brazil
| | - Eufrásia S. Pereira
- LQC-MM: Laboratório de Química Computacional e Modelagem Molecular Departamento de Química, ICEx, Universidade Federal de Minas Gerais 31270-901 Pampulha, Belo Horizonte, Minas Gerais, Brazil
| | - Marina P. B. Godinho
- LQC-MM: Laboratório de Química Computacional e Modelagem Molecular Departamento de Química, ICEx, Universidade Federal de Minas Gerais 31270-901 Pampulha, Belo Horizonte, Minas Gerais, Brazil
| | - Júlio Cosme S. Da Silva
- LQC-MM: Laboratório de Química Computacional e Modelagem Molecular Departamento de Química, ICEx, Universidade Federal de Minas Gerais 31270-901 Pampulha, Belo Horizonte, Minas Gerais, Brazil
- GQC: Grupo de Química Computacional Instituto de Química e Biotecnologia, IQB, Universidade Federal de Alagoas Campus A. C. Simões, 57072-900 Maceió, Alagoas, Brazil
| | - Willian R. Rocha
- LQC-MM: Laboratório de Química Computacional e Modelagem Molecular Departamento de Química, ICEx, Universidade Federal de Minas Gerais 31270-901 Pampulha, Belo Horizonte, Minas Gerais, Brazil
| |
Collapse
|
15
|
Paul TJ, Schenk G, Prabhakar R. Formation of Catalytically Active Binuclear Center of Glycerophosphodiesterase: A Molecular Dynamics Study. J Phys Chem B 2018; 122:5797-5808. [DOI: 10.1021/acs.jpcb.8b02046] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Thomas J. Paul
- Department of Chemistry, University of Miami, Coral Gables, Florida 33146, United States
| | - Gerhard Schenk
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Rajeev Prabhakar
- Department of Chemistry, University of Miami, Coral Gables, Florida 33146, United States
| |
Collapse
|
16
|
Liu S, Invergo AM, McInnis JP, Mouat AR, Motta A, Lohr TL, Delferro M, Marks TJ. Distinctive Stereochemically Linked Cooperative Effects in Bimetallic Titanium Olefin Polymerization Catalysts. Organometallics 2017. [DOI: 10.1021/acs.organomet.7b00641] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Shaofeng Liu
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - Anna M. Invergo
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - Jennifer P. McInnis
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - Aidan R. Mouat
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - Alessandro Motta
- Dipartimento
di Scienze Chimiche, Università di Roma “La Sapienza” and INSTM, UdR Roma, Piazzale Aldo Moro 5, I-00185 Roma, Italy
| | - Tracy L. Lohr
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - Massimiliano Delferro
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - Tobin J. Marks
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| |
Collapse
|
17
|
Pinto G, Mazzone G, Russo N, Toscano M. Trimethylphosphate and Dimethylphosphate Hydrolysis by Binuclear CdII
, MnII
, and ZnII
-FeII
Promiscuous Organophosphate-Degrading Enzyme: Reaction Mechanisms. Chemistry 2017; 23:13742-13753. [DOI: 10.1002/chem.201702379] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Indexed: 11/08/2022]
Affiliation(s)
- Gaspar Pinto
- Department Of Chemistry and Chemical Technologies; University of Calabria; Via P. Bucci 87036 Arcavacata di Rende Italy
| | - Gloria Mazzone
- Department Of Chemistry and Chemical Technologies; University of Calabria; Via P. Bucci 87036 Arcavacata di Rende Italy
| | - Nino Russo
- Department Of Chemistry and Chemical Technologies; University of Calabria; Via P. Bucci 87036 Arcavacata di Rende Italy
| | - Marirosa Toscano
- Department Of Chemistry and Chemical Technologies; University of Calabria; Via P. Bucci 87036 Arcavacata di Rende Italy
| |
Collapse
|
18
|
Pedroso MM, Ely F, Carpenter MC, Mitić N, Gahan LR, Ollis DL, Wilcox DE, Schenk G. Mechanistic Insight from Calorimetric Measurements of the Assembly of the Binuclear Metal Active Site of Glycerophosphodiesterase (GpdQ) from Enterobacter aerogenes. Biochemistry 2017; 56:3328-3336. [DOI: 10.1021/acs.biochem.6b01200] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Marcelo M. Pedroso
- School
of Chemistry and Molecular BioSciences, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Fernanda Ely
- School
of Chemistry and Molecular BioSciences, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Margaret C. Carpenter
- Department
of Chemistry, Dartmouth College, Hanover, New Hampshire 03755, United States
| | - Nataša Mitić
- Department
of Chemistry, National University of Ireland—Maynooth, Maynooth, County Kildare, Ireland
| | - Lawrence R. Gahan
- School
of Chemistry and Molecular BioSciences, The University of Queensland, St Lucia, QLD 4072, Australia
| | - David L. Ollis
- Research
School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
| | - Dean E. Wilcox
- Department
of Chemistry, Dartmouth College, Hanover, New Hampshire 03755, United States
| | - Gerhard Schenk
- School
of Chemistry and Molecular BioSciences, The University of Queensland, St Lucia, QLD 4072, Australia
| |
Collapse
|
19
|
Pedroso MM, Selleck C, Enculescu C, Harmer JR, Mitić N, Craig WR, Helweh W, Hugenholtz P, Tyson GW, Tierney DL, Larrabee JA, Schenk G. Characterization of a highly efficient antibiotic-degrading metallo-β-lactamase obtained from an uncultured member of a permafrost community. Metallomics 2017; 9:1157-1168. [DOI: 10.1039/c7mt00195a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Microorganisms in the permafrost contain a potent mechanism to inactivate antibiotics.
Collapse
|
20
|
Selleck C, Larrabee JA, Harmer J, Guddat LW, Mitić N, Helweh W, Ollis DL, Craig WR, Tierney DL, Monteiro Pedroso M, Schenk G. AIM-1: An Antibiotic-Degrading Metallohydrolase That Displays Mechanistic Flexibility. Chemistry 2016; 22:17704-17714. [DOI: 10.1002/chem.201602762] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Indexed: 12/20/2022]
Affiliation(s)
- Christopher Selleck
- School of Chemistry and Molecular Biosciences; The University of Queensland; St. Lucia Queensland 4072 Australia
| | - James A. Larrabee
- Department of Chemistry and Biochemistry; Middlebury College; Middlebury Vermont 05753 USA
| | - Jeffrey Harmer
- Centre for Advanced Imaging; The University of Queensland; St. Lucia Queensland 4072 Australia
| | - Luke W. Guddat
- School of Chemistry and Molecular Biosciences; The University of Queensland; St. Lucia Queensland 4072 Australia
| | - Nataša Mitić
- Department of Chemistry; Maynooth University; Maynooth, Co. Kildare Ireland
| | - Waleed Helweh
- Department of Chemistry and Biochemistry; Middlebury College; Middlebury Vermont 05753 USA
| | - David L. Ollis
- Research School of Chemistry; Australian National University of Canberra; ACT 0200 Australia
| | - Whitney R. Craig
- Department of Chemistry and Biochemistry; Miami University, Oxford; Ohio 45056 USA
| | - David L. Tierney
- Department of Chemistry and Biochemistry; Miami University, Oxford; Ohio 45056 USA
| | - Marcelo Monteiro Pedroso
- School of Chemistry and Molecular Biosciences; The University of Queensland; St. Lucia Queensland 4072 Australia
| | - Gerhard Schenk
- School of Chemistry and Molecular Biosciences; The University of Queensland; St. Lucia Queensland 4072 Australia
| |
Collapse
|
21
|
Promiscuous metallo-β-lactamases: MIM-1 and MIM-2 may play an essential role in quorum sensing networks. J Inorg Biochem 2016; 162:366-375. [DOI: 10.1016/j.jinorgbio.2015.12.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 12/04/2015] [Accepted: 12/16/2015] [Indexed: 11/21/2022]
|
22
|
Schenk G, Mateen I, Ng TK, Pedroso MM, Mitić N, Jafelicci M, Marques RF, Gahan LR, Ollis DL. Organophosphate-degrading metallohydrolases: Structure and function of potent catalysts for applications in bioremediation. Coord Chem Rev 2016. [DOI: 10.1016/j.ccr.2016.03.006] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
23
|
Tadrowski S, Pedroso MM, Sieber V, Larrabee JA, Guddat LW, Schenk G. Metal Ions Play an Essential Catalytic Role in the Mechanism of Ketol-Acid Reductoisomerase. Chemistry 2016; 22:7427-36. [PMID: 27136273 DOI: 10.1002/chem.201600620] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Indexed: 01/13/2023]
Abstract
Ketol-acid reductoisomerase (KARI) is a Mg(2+) -dependent enzyme in the branched-chain amino acid biosynthesis pathway. It catalyses a complex two-part reaction: an alkyl migration followed by a NADPH-dependent reduction. Both reactions occur within the one active site, but in particular, the mechanism of the isomerisation step is poorly understood. Here, using a combination of kinetic, thermodynamic and spectroscopic techniques, the reaction mechanisms of both Escherichia coli and rice KARI have been investigated. We propose a conserved mechanism of catalysis, whereby a hydroxide, bridging the two Mg(2+) ions in the active site, initiates the reaction by abstracting a proton from the C2 alcohol group of the substrate. While the μ-hydroxide-bridged dimetallic centre is pre-assembled in the bacterial enzyme, in plant KARI substrate binding leads to a reduction of the metal-metal distance with the concomitant formation of a hydroxide bridge. Only Mg(2+) is capable of promoting the isomerisation reaction, likely to be due to non-competent substrate binding in the presence of other metal ions.
Collapse
Affiliation(s)
- Sonya Tadrowski
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Marcelo M Pedroso
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Volker Sieber
- Straubing Center of Science, Technische Universität München, Straubing, Germany
| | - James A Larrabee
- Department of Chemistry and Biochemistry, Middlebury College, Middlebury, VT, 05753, USA
| | - Luke W Guddat
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD 4072, Australia.
| | - Gerhard Schenk
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD 4072, Australia.
| |
Collapse
|
24
|
Sugrue E, Hartley CJ, Scott C, Jackson CJ. The Evolution of New Catalytic Mechanisms for Xenobiotic Hydrolysis in Bacterial Metalloenzymes. Aust J Chem 2016. [DOI: 10.1071/ch16426] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
An increasing number of bacterial metalloenzymes have been shown to catalyse the breakdown of xenobiotics in the environment, while others exhibit a variety of promiscuous xenobiotic-degrading activities. Several different evolutionary processes have allowed these enzymes to gain or enhance xenobiotic-degrading activity. In this review, we have surveyed the range of xenobiotic-degrading metalloenzymes, and discuss the molecular and catalytic basis for the development of new activities. We also highlight how our increased understanding of the natural evolution of xenobiotic-degrading metalloenzymes can be been applied to laboratory enzyme design.
Collapse
|
25
|
Pedroso MM, Larrabee JA, Ely F, Gwee SE, Mitić N, Ollis DL, Gahan LR, Schenk G. Ca(II) Binding Regulates and Dominates the Reactivity of a Transition-Metal-Ion-Dependent Diesterase from Mycobacterium tuberculosis. Chemistry 2015; 22:999-1009. [PMID: 26662456 DOI: 10.1002/chem.201504001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Indexed: 11/07/2022]
Abstract
The diesterase Rv0805 from Mycobacterium tuberculosis is a dinuclear metallohydrolase that plays an important role in signal transduction by controlling the intracellular levels of cyclic nucleotides. As Rv0805 is essential for mycobacterial growth it is a promising new target for the development of chemotherapeutics to treat tuberculosis. The in vivo metal-ion composition of Rv0805 is subject to debate. Here, we demonstrate that the active site accommodates two divalent transition metal ions with binding affinities ranging from approximately 50 nm for Mn(II) to about 600 nm for Zn(II) . In contrast, the enzyme GpdQ from Enterobacter aerogenes, despite having a coordination sphere identical to that of Rv0805, binds only one metal ion in the absence of substrate, thus demonstrating the significance of the outer sphere to modulate metal-ion binding and enzymatic reactivity. Ca(II) also binds tightly to Rv0805 (Kd ≈40 nm), but kinetic, calorimetric, and spectroscopic data indicate that two Ca(II) ions bind at a site different from the dinuclear transition-metal-ion binding site. Ca(II) acts as an activator of the enzymatic activity but is able to promote the hydrolysis of substrates even in the absence of transition-metal ions, thus providing an effective strategy for the regulation of the enzymatic activity.
Collapse
Affiliation(s)
- Marcelo M Pedroso
- School of Chemistry and Molecular BioSciences, The University of Queensland, St. Lucia, QLD 4072, Australia), Fax
| | - James A Larrabee
- Department of Chemistry and Biochemistry, Middlebury College, Middlebury, VT 05753, USA
| | - Fernanda Ely
- School of Chemistry and Molecular BioSciences, The University of Queensland, St. Lucia, QLD 4072, Australia), Fax
| | - Shuhui E Gwee
- School of Chemistry and Molecular BioSciences, The University of Queensland, St. Lucia, QLD 4072, Australia), Fax
| | - Nataša Mitić
- Department of Chemistry, National University of Ireland-Maynooth, Maynooth, Co. Kildare, Ireland
| | - David L Ollis
- Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
| | - Lawrence R Gahan
- School of Chemistry and Molecular BioSciences, The University of Queensland, St. Lucia, QLD 4072, Australia), Fax
| | - Gerhard Schenk
- School of Chemistry and Molecular BioSciences, The University of Queensland, St. Lucia, QLD 4072, Australia), Fax.
| |
Collapse
|
26
|
Use of magnetic circular dichroism to study dinuclear metallohydrolases and the corresponding biomimetics. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2015; 44:393-415. [DOI: 10.1007/s00249-015-1053-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2015] [Revised: 05/30/2015] [Accepted: 06/07/2015] [Indexed: 11/26/2022]
|
27
|
Myers CL, Ireland RG, Garrett TA, Brown ED. Characterization of Wall Teichoic Acid Degradation by the Bacteriophage ϕ29 Appendage Protein GP12 Using Synthetic Substrate Analogs. J Biol Chem 2015; 290:19133-45. [PMID: 26085106 DOI: 10.1074/jbc.m115.662866] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Indexed: 11/06/2022] Open
Abstract
The genetics and enzymology of the biosynthesis of wall teichoic acid have been the extensively studied, however, comparatively little is known regarding the enzymatic degradation of this biological polymer. The GP12 protein from the Bacillus subtilis bacteriophage ϕ29 has been implicated as a wall teichoic acid hydrolase. We have studied the wall teichoic acid hydrolase activity of pure, recombinant GP12 using chemically defined wall teichoic acid analogs. The GP12 protein had potent wall teichoic acid hydrolytic activity in vitro and demonstrated ∼13-fold kinetic preference for glycosylated poly(glycerol phosphate) teichoic acid compared with non-glycosylated. Product distribution patterns suggested that the degradation of glycosylated polymers proceeded from the hydroxyl terminus of the polymer, whereas hydrolysis occurred at random sites in the non-glycosylated polymer. In addition, we present evidence that the GP12 protein possesses both phosphodiesterase and phosphomonoesterase activities.
Collapse
Affiliation(s)
- Cullen L Myers
- From the Department of Biochemistry and Biomedical Sciences, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario L8N 3Z5, Canada and
| | - Ronald G Ireland
- From the Department of Biochemistry and Biomedical Sciences, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario L8N 3Z5, Canada and
| | - Teresa A Garrett
- the Department of Chemistry, Vassar College, Poughkeepsie, New York 12604
| | - Eric D Brown
- From the Department of Biochemistry and Biomedical Sciences, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario L8N 3Z5, Canada and
| |
Collapse
|
28
|
Abstract
Calcineurin-like metallophosphoesterases (MPEs) form a large superfamily of binuclear metal-ion-centre-containing enzymes that hydrolyse phosphomono-, phosphodi- or phosphotri-esters in a metal-dependent manner. The MPE domain is found in Mre11/SbcD DNA-repair enzymes, mammalian phosphoprotein phosphatases, acid sphingomyelinases, purple acid phosphatases, nucleotidases and bacterial cyclic nucleotide phosphodiesterases. Despite this functional diversity, MPEs show a remarkably similar structural fold and active-site architecture. In the present review, we summarize the available structural, biochemical and functional information on these proteins. We also describe how diversification and specialization of the core MPE fold in various MPEs is achieved by amino acid substitution in their active sites, metal ions and regulatory effects of accessory domains. Finally, we discuss emerging roles of these proteins as non-catalytic protein-interaction scaffolds. Thus we view the MPE superfamily as a set of proteins with a highly conserved structural core that allows embellishment to result in dramatic and niche-specific diversification of function.
Collapse
|
29
|
Miraula M, Whitaker JJ, Schenk G, Mitić N. β-Lactam antibiotic-degrading enzymes from non-pathogenic marine organisms: a potential threat to human health. J Biol Inorg Chem 2015; 20:639-51. [PMID: 25773168 DOI: 10.1007/s00775-015-1250-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 03/02/2015] [Indexed: 10/23/2022]
Abstract
Metallo-β-lactamases (MBLs) are a family of Zn(II)-dependent enzymes that inactivate most of the commonly used β-lactam antibiotics. They have emerged as a major threat to global healthcare. Recently, we identified two novel MBL-like proteins, Maynooth IMipenemase-1 (MIM-1) and Maynooth IMipenemase-2 (MIM-2), in the marine organisms Novosphingobium pentaromativorans and Simiduia agarivorans, respectively. Here, we demonstrate that MIM-1 and MIM-2 have catalytic activities comparable to those of known MBLs, but from the pH dependence of their catalytic parameters it is evident that both enzymes differ with respect to their mechanisms, with MIM-1 preferring alkaline and MIM-2 acidic conditions. Both enzymes require Zn(II) but activity can also be reconstituted with other metal ions including Co(II), Mn(II), Cu(II) and Ca(II). Importantly, the substrate preference of MIM-1 and MIM-2 appears to be influenced by their metal ion composition. Since neither N. pentaromativorans nor S. agarivorans are human pathogens, the precise biological role(s) of MIM-1 and MIM-2 remains to be established. However, due to the similarity of at least some of their in vitro functional properties to those of known MBLs, MIM-1 and MIM-2 may provide essential structural insight that may guide the design of as of yet elusive clinically useful MBL inhibitors.
Collapse
Affiliation(s)
- Manfredi Miraula
- Department of Chemistry, Maynooth University, Maynooth, Co., Kildare, Ireland
| | | | | | | |
Collapse
|
30
|
Evolutionary expansion of the amidohydrolase superfamily in bacteria in response to the synthetic compounds molinate and diuron. Appl Environ Microbiol 2015; 81:2612-24. [PMID: 25636851 DOI: 10.1128/aem.04016-14] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The amidohydrolase superfamily has remarkable functional diversity, with considerable structural and functional annotation of known sequences. In microbes, the recent evolution of several members of this family to catalyze the breakdown of environmental xenobiotics is not well understood. An evolutionary transition from binuclear to mononuclear metal ion coordination at the active sites of these enzymes could produce large functional changes such as those observed in nature, but there are few clear examples available to support this hypothesis. To investigate the role of binuclear-mononuclear active-site transitions in the evolution of new function in this superfamily, we have characterized two recently evolved enzymes that catalyze the hydrolysis of the synthetic herbicides molinate (MolA) and phenylurea (PuhB). In this work, the crystal structures, mutagenesis, metal ion analysis, and enzyme kinetics of both MolA and PuhB establish that these enzymes utilize a mononuclear active site. However, bioinformatics and structural comparisons reveal that the closest putative ancestor of these enzymes had a binuclear active site, indicating that a binuclear-mononuclear transition has occurred. These proteins may represent examples of evolution modifying the characteristics of existing catalysts to satisfy new requirements, specifically, metal ion rearrangement leading to large leaps in activity that would not otherwise be possible.
Collapse
|
31
|
Alberto ME, Pinto G, Russo N, Toscano M. Triesterase and Promiscuous Diesterase Activities of a Di-CoII-Containing Organophosphate Degrading Enzyme Reaction Mechanisms. Chemistry 2015; 21:3736-45. [DOI: 10.1002/chem.201405593] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Indexed: 01/08/2023]
|
32
|
Phosphate ester hydrolysis catalyzed by a dinuclear cobalt(II) complex equipped with intramolecular β-cyclodextrins. ACTA ACUST UNITED AC 2015. [DOI: 10.1016/j.molcata.2014.10.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
33
|
Mitić N, Miraula M, Selleck C, Hadler KS, Uribe E, Pedroso MM, Schenk G. Catalytic mechanisms of metallohydrolases containing two metal ions. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2014; 97:49-81. [PMID: 25458355 DOI: 10.1016/bs.apcsb.2014.07.002] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
At least one-third of enzymes contain metal ions as cofactors necessary for a diverse range of catalytic activities. In the case of polymetallic enzymes (i.e., two or more metal ions involved in catalysis), the presence of two (or more) closely spaced metal ions gives an additional advantage in terms of (i) charge delocalisation, (ii) smaller activation barriers, (iii) the ability to bind larger substrates, (iv) enhanced electrostatic activation of substrates, and (v) decreased transition-state energies. Among this group of proteins, enzymes that catalyze the hydrolysis of ester and amide bonds form a very prominent family, the metallohydrolases. These enzymes are involved in a multitude of biological functions, and an increasing number of them gain attention for translational research in medicine and biotechnology. Their functional versatility and catalytic proficiency are largely due to the presence of metal ions in their active sites. In this chapter, we thus discuss and compare the reaction mechanisms of several closely related enzymes with a view to highlighting the functional diversity bestowed upon them by their metal ion cofactors.
Collapse
Affiliation(s)
- Nataša Mitić
- Department of Chemistry, National University of Ireland, Maynooth, Maynooth, Co. Kildare, Ireland.
| | - Manfredi Miraula
- Department of Chemistry, National University of Ireland, Maynooth, Maynooth, Co. Kildare, Ireland; School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Christopher Selleck
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Kieran S Hadler
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Elena Uribe
- Department of Biochemistry and Molecular Biology, University of Concepción, Concepción, Chile
| | - Marcelo M Pedroso
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Gerhard Schenk
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia.
| |
Collapse
|
34
|
Comparative investigation of the reaction mechanisms of the organophosphate-degrading phosphotriesterases from Agrobacterium radiobacter (OpdA) and Pseudomonas diminuta (OPH). J Biol Inorg Chem 2014; 19:1263-75. [DOI: 10.1007/s00775-014-1183-9] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2014] [Accepted: 07/30/2014] [Indexed: 11/26/2022]
|
35
|
300-Fold increase in production of the Zn2+-dependent dechlorinase TrzN in soluble form via apoenzyme stabilization. Appl Environ Microbiol 2014; 80:4003-11. [PMID: 24771025 DOI: 10.1128/aem.00916-14] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Microbial metalloenzymes constitute a large library of biocatalysts, a number of which have already been shown to catalyze the breakdown of toxic chemicals or industrially relevant chemical transformations. However, while there is considerable interest in harnessing these catalysts for biotechnology, for many of the enzymes, their large-scale production in active, soluble form in recombinant systems is a significant barrier to their use. In this work, we demonstrate that as few as three mutations can result in a 300-fold increase in the expression of soluble TrzN, an enzyme from Arthrobacter aurescens with environmental applications that catalyzes the hydrolysis of triazine herbicides, in Escherichia coli. Using a combination of X-ray crystallography, kinetic analysis, and computational simulation, we show that the majority of the improvement in expression is due to stabilization of the apoenzyme rather than the metal ion-bound holoenzyme. This provides a structural and mechanistic explanation for the observation that many compensatory mutations can increase levels of soluble-protein production without increasing the stability of the final, active form of the enzyme. This study provides a molecular understanding of the importance of the stability of metal ion free states to the accumulation of soluble protein and shows that differences between apoenzyme and holoenzyme structures can result in mutations affecting the stability of either state differently.
Collapse
|
36
|
McGeary RP, Schenk G, Guddat LW. The applications of binuclear metallohydrolases in medicine: Recent advances in the design and development of novel drug leads for purple acid phosphatases, metallo-β-lactamases and arginases. Eur J Med Chem 2014; 76:132-44. [DOI: 10.1016/j.ejmech.2014.02.008] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Revised: 01/28/2014] [Accepted: 02/06/2014] [Indexed: 10/25/2022]
|
37
|
Pedroso MM, Ely F, Lonhienne T, Gahan LR, Ollis DL, Guddat LW, Schenk G. Determination of the catalytic activity of binuclear metallohydrolases using isothermal titration calorimetry. J Biol Inorg Chem 2014; 19:389-98. [DOI: 10.1007/s00775-013-1079-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Accepted: 12/12/2013] [Indexed: 11/28/2022]
|
38
|
Phelan EK, Miraula M, Selleck C, Ollis DL, Schenk G, Mitić N. Metallo-β-Lactamases: A Major Threat to Human Health. ACTA ACUST UNITED AC 2014. [DOI: 10.4236/ajmb.2014.43011] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
39
|
Daumann LJ, Schenk G, Ollis DL, Gahan LR. Spectroscopic and mechanistic studies of dinuclear metallohydrolases and their biomimetic complexes. Dalton Trans 2013; 43:910-28. [PMID: 24135968 DOI: 10.1039/c3dt52287c] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An enhanced understanding of the metal ion binding and active site structural features of phosphoesterases such as the glycerophosphodiesterase from Enterobacter aerogenes (GpdQ), and the organophosphate degrading agent from Agrobacterium radiobacter (OpdA) have important consequences for potential applications. Coupled with investigations of the metalloenzymes, programs of study to synthesise and characterise model complexes based on these metalloenzymes can add to our understanding of structure and function of the enzymes themselves. This review summarises some of our work and illustrates the significance and contributions of model studies to knowledge in the area.
Collapse
Affiliation(s)
- Lena J Daumann
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia.
| | | | | | | |
Collapse
|
40
|
Daumann LJ, Larrabee JA, Ollis D, Schenk G, Gahan LR. Immobilization of the enzyme GpdQ on magnetite nanoparticles for organophosphate pesticide bioremediation. J Inorg Biochem 2013; 131:1-7. [PMID: 24239906 DOI: 10.1016/j.jinorgbio.2013.10.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Revised: 10/08/2013] [Accepted: 10/08/2013] [Indexed: 01/26/2023]
Abstract
Annually thousands of people die or suffer from organophosphate (pesticide) poisoning. In order to remove these toxic compounds from the environment, the use of enzymes as bioremediators has been proposed. We report here a Ser127Ala mutant based on the enzyme glycerophosphodiesterase (GpdQ) from Enterobacter aerogenes. The mutant, with improved metal binding abilities, has been immobilized using glutaraldehyde on PAMAM dendrimer-modified magnetite nanoparticles. The immobilized system was characterized using elemental analysis as well as infrared, transmission electron and X-ray photoelectron spectroscopies. The amount of GpdQ that was immobilized with the optimized procedure was 1.488 nmol per g MNP. A kinetic assay has been designed to evaluate the activity of the system towards organophosphoester substrates. The specific activity towards BPNPP directly after immobilization was 3.55 μmol mg(-1)min(-1), after one week 3.39 μmol mg(-1)min(-1) and after 120 days 3.36 μmol mg(-1)min(-1), demonstrating that the immobilized enzyme was active for multiple cycles and could be stored on the nanoparticles for a prolonged period.
Collapse
Affiliation(s)
- Lena J Daumann
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane QLD 4072, Australia
| | - James A Larrabee
- Department of Chemistry and Biochemistry, Middlebury College, Middlebury VT 05753, USA
| | - David Ollis
- Research School of Chemistry, Australian National University, Canberra 0200, Australia
| | - Gerhard Schenk
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane QLD 4072, Australia
| | - Lawrence R Gahan
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane QLD 4072, Australia.
| |
Collapse
|
41
|
Identification and characterization of an unusual metallo-β-lactamase from Serratia proteamaculans. J Biol Inorg Chem 2013; 18:855-63. [DOI: 10.1007/s00775-013-1035-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Accepted: 08/14/2013] [Indexed: 11/25/2022]
|
42
|
Daumann LJ, Comba P, Larrabee JA, Schenk G, Stranger R, Cavigliasso G, Gahan LR. Synthesis, Magnetic Properties, and Phosphoesterase Activity of Dinuclear Cobalt(II) Complexes. Inorg Chem 2013; 52:2029-43. [DOI: 10.1021/ic302418x] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Lena J. Daumann
- School of
Chemistry and Molecular Biosciences, The University of Queensland, Brisbane QLD 4072, Australia
| | - Peter Comba
- Anorganisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld
270, 69120 Heidelberg, Germany
| | - James A. Larrabee
- Department of Chemistry and Biochemistry, Middlebury College, Middlebury, Vermont 05753, United States
| | - Gerhard Schenk
- School of
Chemistry and Molecular Biosciences, The University of Queensland, Brisbane QLD 4072, Australia
- Department of Chemistry, National University of Ireland—Maynooth, Maynooth,
Co. Kildare, Ireland
| | - Robert Stranger
- Research School of Chemistry, Australian National University, Canberra 0200, Australia
| | - German Cavigliasso
- Research School of Chemistry, Australian National University, Canberra 0200, Australia
| | - Lawrence R. Gahan
- School of
Chemistry and Molecular Biosciences, The University of Queensland, Brisbane QLD 4072, Australia
| |
Collapse
|
43
|
Schenk G, Mitić N, Gahan LR, Ollis DL, McGeary RP, Guddat LW. Binuclear metallohydrolases: complex mechanistic strategies for a simple chemical reaction. Acc Chem Res 2012; 45:1593-603. [PMID: 22698580 DOI: 10.1021/ar300067g] [Citation(s) in RCA: 113] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Binuclear metallohydrolases are a large family of enzymes that require two closely spaced transition metal ions to carry out a plethora of hydrolytic reactions. Representatives include purple acid phosphatases (PAPs), enzymes that play a role in bone metabolism and are the only member of this family with a heterovalent binuclear center in the active form (Fe(3+)-M(2+), M = Fe, Zn, Mn). Other members of this family are urease, which contains a di-Ni(2+) center and catalyzes the breakdown of urea, arginase, which contains a di-Mn(2+) center and catalyzes the final step in the urea cycle, and the metallo-β-lactamases, which contain a di-Zn(2+) center and are virulence factors contributing to the spread of antibiotic-resistant pathogens. Binuclear metallohydrolases catalyze numerous vital reactions and are potential targets of drugs against a wide variety of human disorders including osteoporosis, various cancers, antibiotic resistance, and erectile dysfunctions. These enzymes also tend to catalyze more than one reaction. An example is an organophosphate (OP)-degrading enzyme from Enterobacter aerogenes (GpdQ). Although GpdQ is part of a pathway that is used by bacteria to degrade glycerolphosphoesters, it hydrolyzes a variety of other phosphodiesters and displays low levels of activity against phosphomono- and triesters. Such a promiscuous nature may have assisted the apparent recent evolution of some binuclear metallohydrolases to deal with situations created by human intervention such as OP pesticides in the environment. OP pesticides were first used approximately 70 years ago, and therefore the enzymes that bacteria use to degrade them must have evolved very quickly on the evolutionary time scale. The promiscuous nature of enzymes such as GpdQ makes them ideal candidates for the application of directed evolution to produce new enzymes that can be used in bioremediation and against chemical warfare. In this Account, we review the mechanisms employed by binuclear metallohydrolases and use PAP, the OP-degrading enzyme from Agrobacterium radiobacter (OPDA), and GpdQ as representative systems because they illustrate both the diversity and similarity of the reactions catalyzed by this family of enzymes. The majority of binuclear metallohydrolases utilize metal ion-activated water molecules as nucleophiles to initiate hydrolysis, while some, such as alkaline phosphatase, employ an intrinsic polar amino acid. Here we only focus on catalytic strategies applied by the former group.
Collapse
Affiliation(s)
- Gerhard Schenk
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Department of Chemistry, National University of Ireland—Maynooth, Maynooth, County Kildare, Ireland
| | - Nataša Mitić
- Department of Chemistry, National University of Ireland—Maynooth, Maynooth, County Kildare, Ireland
| | - Lawrence R. Gahan
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - David L. Ollis
- Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
| | - Ross P. McGeary
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Luke W. Guddat
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| |
Collapse
|
44
|
Daumann LJ, Gahan LR, Comba P, Schenk G. Cadmium(II) Complexes: Mimics of Organophosphate Pesticide Degrading Enzymes and Metallo-β-lactamases. Inorg Chem 2012; 51:7669-81. [DOI: 10.1021/ic300687y] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lena J. Daumann
- School of
Chemistry and Molecular
Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Lawrence. R. Gahan
- School of
Chemistry and Molecular
Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Peter Comba
- Anorganisch-Chemisches Institut, Universitat Heidelberg, Im Neuenheimer Feld 270, 69120
Heidelberg, Germany
| | - Gerhard Schenk
- School of
Chemistry and Molecular
Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Department
of Chemistry, National University of Ireland, Maynooth, County Kildare,
Ireland
| |
Collapse
|
45
|
Daumann LJ, McCarthy BY, Hadler KS, Murray TP, Gahan LR, Larrabee JA, Ollis DL, Schenk G. Promiscuity comes at a price: catalytic versatility vs efficiency in different metal ion derivatives of the potential bioremediator GpdQ. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2012; 1834:425-32. [PMID: 22366468 DOI: 10.1016/j.bbapap.2012.02.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2011] [Revised: 01/26/2012] [Accepted: 02/03/2012] [Indexed: 10/28/2022]
Abstract
The glycerophosphodiesterase from Enterobacter aerogenes (GpdQ) is a highly promiscuous dinuclear metallohydrolase with respect to both substrate specificity and metal ion composition. While this promiscuity may adversely affect the enzyme's catalytic efficiency its ability to hydrolyse some organophosphates (OPs) and by-products of OP degradation have turned GpdQ into a promising candidate for bioremedial applications. Here, we investigated both metal ion binding and the effect of the metal ion composition on catalysis. The prevalent in vivo metal ion composition for GpdQ is proposed to be of the type Fe(II)Zn(II), a reflection of natural abundance rather than catalytic optimisation. The Fe(II) appears to have lower binding affinity than other divalent metal ions, and the catalytic efficiency of this mixed metal center is considerably smaller than that of Mn(II), Co(II) or Cd(II)-containing derivatives of GpdQ. Interestingly, metal ion replacements do not only affect catalytic efficiency but also the optimal pH range for the reaction, suggesting that different metal ion combinations may employ different mechanistic strategies. These metal ion-triggered modulations are likely to be mediated via an extensive hydrogen bond network that links the two metal ion binding sites via residues in the substrate binding pocket. The observed functional diversity may be the cause for the modest catalytic efficiency of wild-type GpdQ but may also be essential to enable the enzyme to evolve rapidly to alter substrate specificity and enhance k(cat) values, as has recently been demonstrated in a directed evolution experiment. This article is part of a Special Issue entitled: Chemistry and mechanism of phosphatases, diesterases and triesterases.
Collapse
Affiliation(s)
- Lena J Daumann
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD 4072, Australia
| | | | | | | | | | | | | | | |
Collapse
|
46
|
Yip SHC, Foo JL, Schenk G, Gahan LR, Carr PD, Ollis DL. Directed evolution combined with rational design increases activity of GpdQ toward a non-physiological substrate and alters the oligomeric structure of the enzyme. Protein Eng Des Sel 2011; 24:861-72. [DOI: 10.1093/protein/gzr048] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
|
47
|
Electronic and geometric structures of the organophosphate-degrading enzyme from Agrobacterium radiobacter (OpdA). J Biol Inorg Chem 2011; 16:777-87. [PMID: 21487938 DOI: 10.1007/s00775-011-0779-6] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Accepted: 03/28/2011] [Indexed: 10/18/2022]
Abstract
The organophosphate-degrading enzyme from Agrobacterium radiobacter (OpdA) is a highly efficient catalyst for the degradation of pesticides and some nerve agents such as sarin. OpdA requires two metal ions for catalytic activity, and hydrolysis is initiated by a nucleophilic hydroxide that is bound to one of these metal ions. The precise location of this nucleophile has been contentious, with both a terminal and a metal-ion-bridging hydroxide as likely candidates. Here, we employed magnetic circular dichroism to probe the electronic and geometric structures of the Co(II)-reconstituted dinuclear metal center in OpdA. In the resting state the metal ion in the more secluded α site is five-coordinate, whereas the Co(II) in the solvent-exposed β site is predominantly six-coordinate with two terminal water ligands. Addition of the slow substrate diethyl 4-methoxyphenyl phosphate does not affect the α site greatly but lowers the coordination number of the β site to five. A reduction in the exchange coupling constant indicates that substrate binding also triggers a shift of the μ-hydroxide into a pseudoterminal position in the coordination sphere of either the α or the β metal ion. Mechanistic implications of these observations are discussed.
Collapse
|
48
|
The organophosphate-degrading enzyme from Agrobacterium radiobacter displays mechanistic flexibility for catalysis. Biochem J 2011; 432:565-73. [PMID: 20868365 DOI: 10.1042/bj20101054] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The OP (organophosphate)-degrading enzyme from Agrobacterium radiobacter (OpdA) is a binuclear metallohydrolase able to degrade highly toxic OP pesticides and nerve agents into less or non-toxic compounds. In the present study, the effect of metal ion substitutions and site-directed mutations on the catalytic properties of OpdA are investigated. The study shows the importance of both the metal ion composition and a hydrogen-bond network that connects the metal ion centre with the substrate-binding pocket using residues Arg254 and Tyr257 in the mechanism and substrate specificity of this enzyme. For the Co(II) derivative of OpdA two protonation equilibria (pKa1 ~5; pKa2 ~10) have been identified as relevant for catalysis, and a terminal hydroxide acts as the likely hydrolysis-initiating nucleophile. In contrast, the Zn(II) and Cd(II) derivatives only have one relevant protonation equilibrium (pKa ~4-5), and the μOH is the proposed nucleophile. The observed mechanistic flexibility may reconcile contrasting reaction models that have been published previously and may be beneficial for the rapid adaptation of OP-degrading enzymes to changing environmental pressures.
Collapse
|
49
|
Zee YLM, Gahan LR, Schenk G. A Potentially Polymerizable Heterodinuclear FeIIIZnII Purple Acid Phosphatase Mimic. Synthesis, Characterization, and Phosphate Ester Hydrolysis Studies. Aust J Chem 2011. [DOI: 10.1071/ch10424] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
An analogue of the purple acid phosphatase biomimetic 2-((bis(pyridin-2-ylmethyl)amino)methyl)-6-(((2-hydroxybenzyl)(pyridin-2-ylmethyl)amino)methyl)-4-methylphenol has been synthesized. The analogue, 2-((bis(pyridin-2-ylmethyl)amino)methyl)-6-(((2-hydroxy-4-(4-vinylbenzyloxy)benzyl)(pyridin-2-ylmethyl)amino)methyl)-4-methylphenol (H2BPBPMPV) possesses a pendant olefin suitable for copolymerization. Complexation with FeIII/ZnII resulted in the complex [FeIIIZnII(BPBPMPV)(CH3COO)2](ClO4), characterized with mass spectrometry, microanalysis, UV/vis, and IR spectrometry. The catalytic activity of the complex toward bis-(2,4-dinitrophenyl) phosphate was determined, resulting in Km of 4.1 ± 0.6 mM, with kcat 3.8 ± 0.2 × 10–3 s–1 and a bell-shaped pH–rate profile with pKa values of 4.31, 5.66, 8.96, the profile exhibiting residual activity above pH 9.5.
Collapse
|
50
|
Park JM, Boero M. Protonation of a hydroxide anion bridging two divalent magnesium cations in water probed by first-principles metadynamics simulation. J Phys Chem B 2010; 114:11102-9. [PMID: 20695500 DOI: 10.1021/jp102991f] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The protonation of a hydroxide anion (OH(-)) located between two magnesium cations (Mg(2+)) in aqueous solution has been investigated by first-principles metadynamics simulation. We observe that the complex Mg(2+)-OH(-)-Mg(2+) is stabilized by the coparticipation of the hydroxide anion to the first hydration shells of both the Mg(2+) cations. Contrary to the cases of OH(-) in pure water, the transfer of protons in the presence of the divalent metal ions turns out to be a slow chemical event. This can be ascribed to the decreased proton affinity of the bridging OH(-). Metadynamics simulation, used to overcome the difficulty of the long time scale required by the protonation of the bridging OH(-), has shown that the system possesses a great stability on the reactant state, characterized by a bioctahedral (6,6) solvation structure around the two Mg(2+) cations. The exploration of the free energy landscape shows that this stable bioctahedral configuration converts into a lower coordinated (5,6) structure, leading to a proton transfer from a water molecule belonging to the first solvation shell of the Mg(2+) ion having the lower coordination to the bridging OH(-); the free energy barrier for the protonation reaction is 11 kcal/mol, meaning that the bridging hydroxide is a weak base. During the proton transfer, the bridging OH(-) reverts to an H(2)O molecule, and this breaks the electrostatic coupling of the two Mg(2+) ions, which depart independently with their own hydration shells, one of which is entirely formed by water molecules. The second one carries the newly created OH(-). Our results show that the flexibility in the metal coordination plays a crucial role in both the protonation process of the bridging OH(-) and the separation of the metal cations, providing useful insight into the nature of proton transfer in binuclear divalent metal ions, with several biological implications, such as, for instance, transesterification of catalytic RNA.
Collapse
Affiliation(s)
- Jung Mee Park
- Department of Chemistry, Sungkyunkwan University, Suwon, Gyeonggi, 440-746, Korea.
| | | |
Collapse
|