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Singh S, Gola C, Singh B, Agrawal V, Chaba R. D-galactonate metabolism in enteric bacteria: a molecular and physiological perspective. Curr Opin Microbiol 2024; 81:102524. [PMID: 39137493 DOI: 10.1016/j.mib.2024.102524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2024] [Revised: 07/31/2024] [Accepted: 07/31/2024] [Indexed: 08/15/2024]
Abstract
D-galactonate, a widely prevalent sugar acid, was first reported as a nutrient source for enteric bacteria in the 1970s. Since then, decades of research enabled a description of the modified Entner-Doudoroff pathway involved in its degradation and reported the structural and biochemical features of its metabolic enzymes, primarily in Escherichia coli K-12. However, only in the last few years, the D-galactonate transporter has been characterized, and the regulation of the dgo operon, encoding the structural genes for the transporter and enzymes of D-galactonate metabolism, has been detailed. Notably, in recent years, multiple evolutionary studies have identified the dgo operon as a dominant target for adaptation of E. coli in the mammalian gut. Despite considerable research on dgo operon, numerous fundamental questions remain to be addressed. The emerging relevance of the dgo operon in host-bacterial interactions further necessitates the study of D-galactonate metabolism in other enterobacterial strains.
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Affiliation(s)
- Swati Singh
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, SAS Nagar, Punjab 140306, India
| | - Chetna Gola
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, SAS Nagar, Punjab 140306, India
| | - Bhupinder Singh
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, SAS Nagar, Punjab 140306, India
| | - Vishal Agrawal
- Amity School of Biological Sciences, Amity University Punjab, Mohali, SAS Nagar, Punjab 140306, India
| | - Rachna Chaba
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, SAS Nagar, Punjab 140306, India.
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2
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McGary LC, Fetter CM, Gu M, Hamilton MC, Kumar H, Kuehm OP, Douglas CD, Bearne SL. Interrogating l-fuconate dehydratase with tartronate and 3-hydroxypyruvate reveals subtle differences within the mandelate racemase-subgroup of the enolase superfamily. Arch Biochem Biophys 2024; 754:109924. [PMID: 38354877 DOI: 10.1016/j.abb.2024.109924] [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] [Received: 12/16/2023] [Revised: 01/27/2024] [Accepted: 02/05/2024] [Indexed: 02/16/2024]
Abstract
Enzymes of the enolase superfamily share a conserved structure and a common partial reaction (i.e., metal-assisted, Brønsted base-catalyzed enol(ate) formation). The architectures of the enolization apparatus at the active sites of the mandelate racemase (MR)-subgroup members MR and l-fuconate dehydratase (FucD) are almost indistinguishable at the structural level. Tartronate and 3-hydroxypyruvate (3-HP) recognize the enolization apparatus and can be used to interrogate the active sites for differences that may not be apparent from structural data. We report a circular dichroism-based assay of FucD activity that monitors the change in ellipticity at 216 nm (Δ[Θ]S-P = 8985 ± 87 deg cm2 mol-1) accompanying the conversion of l-fuconate to 2-keto-3-deoxy-l-fuconate. Tartronate was a linear mixed-type inhibitor of FucD (Ki = 8.4 ± 0.7 mM, αKi = 63 ± 11 mM), binding 18-fold weaker than l-fuconate, compared with 2-fold weaker binding of tartronate by MR relative to mandelate. 3-HP irreversibly inactivated FucD (kinact/KI = 0.018 ± 0.002 M-1s-1) with an efficiency that was ∼4.6 × 103-fold less than that observed with MR. The inactivation arose predominantly from modifications at multiple sites and Tris-HCl, but not l-fuconate, afforded protection against inactivation. Similar to the reaction of 3-HP with MR, 3-HP modified the Brønsted base catalyst (Lys 220) at the active site of FucD, which was facilitated by the Brønsted acid catalyst His 351. Thus, the interactions of tartronate and 3-HP with MR and FucD revealed differences in binding affinity and reactivity that differentiated between the enzymes' enolization apparatuses.
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Affiliation(s)
- Laura C McGary
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, B3H 4R2, Canada
| | - Christopher M Fetter
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, B3H 4R2, Canada
| | - Minglu Gu
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, B3H 4R2, Canada
| | - Meghan C Hamilton
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, B3H 4R2, Canada
| | - Himank Kumar
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, B3H 4R2, Canada
| | - Oliver P Kuehm
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, B3H 4R2, Canada
| | - Colin D Douglas
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, B3H 4R2, Canada
| | - Stephen L Bearne
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, B3H 4R2, Canada; Department of Chemistry, Dalhousie University, Halifax, NS, B3H 4R2, Canada.
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3
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Jeffery CJ. Current successes and remaining challenges in protein function prediction. FRONTIERS IN BIOINFORMATICS 2023; 3:1222182. [PMID: 37576715 PMCID: PMC10415035 DOI: 10.3389/fbinf.2023.1222182] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2023] [Accepted: 07/03/2023] [Indexed: 08/15/2023] Open
Abstract
In recent years, improvements in protein function prediction methods have led to increased success in annotating protein sequences. However, the functions of over 30% of protein-coding genes remain unknown for many sequenced genomes. Protein functions vary widely, from catalyzing chemical reactions to binding DNA or RNA or forming structures in the cell, and some types of functions are challenging to predict due to the physical features associated with those functions. Other complications in understanding protein functions arise due to the fact that many proteins have more than one function or very small differences in sequence or structure that correspond to different functions. We will discuss some of the recent developments in predicting protein functions and some of the remaining challenges.
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Affiliation(s)
- Constance J. Jeffery
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, United States
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4
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Bearne SL, Hayden JA. Application of circular dichroism-based assays to racemases and epimerases: Recognition and catalysis of reactions of chiral substrates by mandelate racemase. Methods Enzymol 2023; 685:127-169. [PMID: 37245900 DOI: 10.1016/bs.mie.2023.03.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Racemases and epimerases have attracted much interest because of their astonishing ability to catalyze the rapid α-deprotonation of carbon acid substrates with high pKa values (∼13-30) leading to the formation of d-amino acids or various carbohydrate diastereomers that serve important roles in both normal physiology and pathology. Enzymatic assays to measure the initial rates of reactions catalyzed by these enzymes are discussed using mandelate racemase (MR) as an example. For MR, a convenient, rapid, and versatile circular dichroism (CD)-based assay has been used to determine the kinetic parameters accompanying the MR-catalyzed racemization of mandelate and alternative substrates. This direct, continuous assay permits real time monitoring of reaction progress, the rapid determination of initial velocities, and immediate recognition of anomalous behaviors. MR recognizes chiral substrates primarily through interactions of the phenyl ring of (R)- or (S)-mandelate with the hydrophobic R- or S-pocket at the active site, respectively. During catalysis, the carboxylate and α-hydroxyl groups of the substrate remain fixed in place through interactions with the Mg2+ ion and multiple H-bonding interactions, while the phenyl ring moves between the R- and S-pockets. The minimal requirements for the substrate appear to be the presence of a glycolate or glycolamide moiety, and a hydrophobic group of limited size that can stabilize the carbanionic intermediate through resonance or strong inductive effects. Similar CD-based assays may be applied to determine the activity of other racemases or epimerases with proper consideration of the molar ellipticity, wavelength, overall absorbance of the sample, and the light pathlength.
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Affiliation(s)
- Stephen L Bearne
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, Canada; Department of Chemistry, Dalhousie University, Halifax, NS, Canada.
| | - Joshua A Hayden
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, Canada
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5
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Aguilera Flores MM, Sánchez Castro MA, Ávila Vázquez V, Correa Aguado HC, García Torres J. Evaluation of the lipase from castor bean ( Ricinus Communis L.) as a potential agent for the remediation of used lubricating oil contaminated soils. JOURNAL OF ENVIRONMENTAL HEALTH SCIENCE & ENGINEERING 2022; 20:657-673. [PMID: 36406614 PMCID: PMC9672203 DOI: 10.1007/s40201-022-00806-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 02/16/2022] [Accepted: 05/30/2022] [Indexed: 06/16/2023]
Abstract
Bioremediation of hydrocarbons-contaminated soils, using enzymes, is considered an alternative technology for soil remediation, obtaining shorter remediation times, greater removal efficiencies, and less waste generation. The lipases from invasive plants such as castor bean (Ricinus Communis L.) could represent an opportunity for its application in this purpose. This paper reports the results of evaluating enzymatic treatment at different conditions for the remediation of used lubricating oil-contaminated soils. Four assays were performed for the removal of the contaminant in a soil sample: (1) natural attenuation and (2) biostimulation with urea (10% w/v), both used as blanks, (3) enzymatic treatment with lipases at ambient conditions (room temperature, soil pH) and (4) enzymatic treatment with lipases at ideal conditions (temperature 37 °C, pH 4.5). After seven weeks of treatment, removal percentages of 14.23 ± 1.92%, 35.71 ± 5.17%, 14.11 ± 6.71%, and 94.26 ± 1.91%, respectively, were obtained. The degradation of the contaminant was analyzed by Fourier-transform Infrared spectroscopy (FTIR) for each assay. Results show the potential of the lipases for catalyzing the degradation of this contaminant in the soil at ideal conditions, representing an alternative technology to be applied as treatment ex-situ. This paper is the first study known to show the utilization of castor bean lipase for the remediation of hydrocarbons-contaminated soils.
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Affiliation(s)
- Miguel Mauricio Aguilera Flores
- Environmental Engineering, Interdisciplinary Professional Unit of Engineering Campus Zacatecas, Instituto Politécnico Nacional, Blvd. del Bote 202 Cerro del Gato Ejido La Escondida, Col. Ciudad Administrativa, 98160 Zacatecas, Zac Mexico
| | - Manuel Alexis Sánchez Castro
- Environmental Engineering, Interdisciplinary Professional Unit of Engineering Campus Zacatecas, Instituto Politécnico Nacional, Blvd. del Bote 202 Cerro del Gato Ejido La Escondida, Col. Ciudad Administrativa, 98160 Zacatecas, Zac Mexico
| | - Verónica Ávila Vázquez
- Environmental Engineering, Interdisciplinary Professional Unit of Engineering Campus Zacatecas, Instituto Politécnico Nacional, Blvd. del Bote 202 Cerro del Gato Ejido La Escondida, Col. Ciudad Administrativa, 98160 Zacatecas, Zac Mexico
| | - Hans Christian Correa Aguado
- Environmental Engineering, Interdisciplinary Professional Unit of Engineering Campus Zacatecas, Instituto Politécnico Nacional, Blvd. del Bote 202 Cerro del Gato Ejido La Escondida, Col. Ciudad Administrativa, 98160 Zacatecas, Zac Mexico
| | - Jésica García Torres
- Environmental Engineering, Interdisciplinary Professional Unit of Engineering Campus Zacatecas, Instituto Politécnico Nacional, Blvd. del Bote 202 Cerro del Gato Ejido La Escondida, Col. Ciudad Administrativa, 98160 Zacatecas, Zac Mexico
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6
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Tripathi A, Dutta Dubey K. Combined MD and QM/MM Calculations Reveal Allostery-Driven Promiscuity in Dipeptide Epimerases of Enolase Family. Chem Asian J 2022; 17:e202200528. [PMID: 35722826 DOI: 10.1002/asia.202200528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 06/19/2022] [Indexed: 11/10/2022]
Abstract
The adaptability of the active site to amplify the secondary function is supposed to be the fundamental cause of the promiscuity and the evolution of new functions in enzymes. In most cases, mutations occur close to the active site and/or in the catalytic site to change the active site plasticity to accommodate the non-native substrate. In the present study, using MD simulations and hybrid QM/MM calculations, we have shown a way to enhance the promiscuity, i. e., the allostery-driven promiscuity. Using a case study of the AEE enzyme where the capping loop recognizes the substrate, herein, we show that a single site mutation (D321G) far from the capping loop can induce a large conformational change in the capping loop to recognize different substrates for different functions. The QM/MM calculations for the WT and mutated enzyme provide a first validation of the mechanism of 1,1-proton transfer and dehydration by the AEE enzyme. Since AEE epimerase possesses a highly conserved TIM-barrel fold, we believe that our study provides a crucial lead to understanding the mechanism of emergence of secondary function which can be useful to repurpose ancient enzymes for modern usage.
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Affiliation(s)
- Ankita Tripathi
- Department of Chemistry, School of Natural Science, Shiv Nadar University Delhi-NCR, NH91 Tehsil Dadri, Greater Noida, Uttar Pradesh, 201314, India
| | - Kshatresh Dutta Dubey
- Department of Chemistry, School of Natural Science, Shiv Nadar University Delhi-NCR, NH91 Tehsil Dadri, Greater Noida, Uttar Pradesh, 201314, India.,Center for Informatics, Department of Chemistry, School of Natural Science, Shiv Nadar University Delhi-NCR, NH91 Tehsil Dadri, Greater Noida, Uttar Pradesh, 201314, India
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7
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González JM, Martí-Arbona R, Chen JCH, Unkefer CJ. The structure of Synechococcus elongatus enolase reveals key aspects of phosphoenolpyruvate binding. Acta Crystallogr F Struct Biol Commun 2022; 78:177-184. [PMID: 35400670 PMCID: PMC8996150 DOI: 10.1107/s2053230x22003612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 03/30/2022] [Indexed: 11/10/2022] Open
Abstract
A structure-function characterization of Synechococcus elongatus enolase (SeEN) is presented, representing the first structural report on a cyanobacterial enolase. X-ray crystal structures of SeEN in its apoenzyme form and in complex with phosphoenolpyruvate are reported at 2.05 and 2.30 Å resolution, respectively. SeEN displays the typical fold of enolases, with a conformationally flexible loop that closes the active site upon substrate binding, assisted by two metal ions that stabilize the negatively charged groups. The enzyme exhibits a catalytic efficiency of 1.2 × 105 M-1 s-1 for the dehydration of 2-phospho-D-glycerate, which is comparable to the kinetic parameters of related enzymes. These results expand the understanding of the biophysical features of these enzymes, broadening the toolbox for metabolic engineering applications.
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Affiliation(s)
- Javier M. González
- Instituto de Bionanotecnología del NOA (INBIONATEC–CONICET), Universidad Nacional de Santiago del Estero (UNSE), RN9, Km1125, G4206XCP Santiago del Estero, Argentina
| | | | - Julian C.-H. Chen
- Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Clifford J. Unkefer
- Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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8
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Chen MH, Li YS, Hsu NS, Lin KH, Wang YL, Wang ZC, Chang CF, Lin JP, Chang CY, Li TL. Structural and Mechanistic Bases for StnK3 and Its Mutant-Mediated Lewis-Acid-Dependent Epimerization and Retro-Aldol Reactions. ACS Catal 2022. [DOI: 10.1021/acscatal.1c04790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mei-Hua Chen
- Genomics Research Center, Academia Sinica, Taipei 115, Taiwan
- Chemical Biology and Molecular Biophysics Program, Taiwan International Graduate Program, Academia Sinica, Taipei 115, Taiwan
- Department of Chemistry, National Taiwan University, Taipei 106, Taiwan
| | - Yi-Shan Li
- Genomics Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Ning-Shian Hsu
- Genomics Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Kuan-Hung Lin
- Genomics Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Yung-Lin Wang
- Genomics Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Zhe-Chong Wang
- Genomics Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Chi-Fon Chang
- Genomics Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Jin-Ping Lin
- Genomics Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Chin-Yuan Chang
- Department of Biological Science and Technology, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
| | - Tsung-Lin Li
- Genomics Research Center, Academia Sinica, Taipei 115, Taiwan
- Chemical Biology and Molecular Biophysics Program, Taiwan International Graduate Program, Academia Sinica, Taipei 115, Taiwan
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, Academia Sinica and National Chung Hsing University, Taipei 115, Taiwan
- Biotechnology Center, National Chung Hsing University, Taichung City 402, Taiwan
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9
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Nagar M, Hayden JA, Sagey E, Worthen G, Park M, Sharma AN, Fetter CM, Kuehm OP, Bearne SL. Altering the binding determinant on the interdigitating loop of mandelate racemase shifts specificity towards that of d-tartrate dehydratase. Arch Biochem Biophys 2022; 718:109119. [DOI: 10.1016/j.abb.2022.109119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 01/05/2022] [Accepted: 01/06/2022] [Indexed: 11/02/2022]
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10
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Truong DP, Rousseau S, Machala BW, Huddleston JP, Zhu M, Hull KG, Romo D, Raushel FM, Sacchettini JC, Glasner ME. Second-Shell Amino Acid R266 Helps Determine N-Succinylamino Acid Racemase Reaction Specificity in Promiscuous N-Succinylamino Acid Racemase/ o-Succinylbenzoate Synthase Enzymes. Biochemistry 2021; 60:3829-3840. [PMID: 34845903 DOI: 10.1021/acs.biochem.1c00627] [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
Catalytic promiscuity is the coincidental ability to catalyze nonbiological reactions in the same active site as the native biological reaction. Several lines of evidence show that catalytic promiscuity plays a role in the evolution of new enzyme functions. Thus, studying catalytic promiscuity can help identify structural features that predispose an enzyme to evolve new functions. This study identifies a potentially preadaptive residue in a promiscuous N-succinylamino acid racemase/o-succinylbenzoate synthase (NSAR/OSBS) enzyme from Amycolatopsis sp. T-1-60. This enzyme belongs to a branch of the OSBS family which includes many catalytically promiscuous NSAR/OSBS enzymes. R266 is conserved in all members of the NSAR/OSBS subfamily. However, the homologous position is usually hydrophobic in other OSBS subfamilies, whose enzymes lack NSAR activity. The second-shell amino acid R266 is close to the catalytic acid/base K263, but it does not contact the substrate, suggesting that R266 could affect the catalytic mechanism. Mutating R266 to glutamine in Amycolatopsis NSAR/OSBS profoundly reduces NSAR activity but moderately reduces OSBS activity. This is due to a 1000-fold decrease in the rate of proton exchange between the substrate and the general acid/base catalyst K263. This mutation is less deleterious for the OSBS reaction because K263 forms a cation-π interaction with the OSBS substrate and/or the intermediate, rather than acting as a general acid/base catalyst. Together, the data explain how R266 contributes to NSAR reaction specificity and was likely an essential preadaptation for the evolution of NSAR activity.
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Affiliation(s)
- Dat P Truong
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, Texas 77843-2128, United States
| | - Simon Rousseau
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, Texas 77843-2128, United States
| | - Benjamin W Machala
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, Texas 77843-2128, United States
| | - Jamison P Huddleston
- Department of Chemistry, Texas A&M University, 3255 TAMU, College Station, Texas 77843-3255, United States
| | - Mingzhao Zhu
- Baylor Synthesis and Drug-Lead Discovery Laboratory, Department of Chemistry and Biochemistry, Baylor University, One Bear Place, Waco, Texas 76798-7348, United States
| | - Kenneth G Hull
- Baylor Synthesis and Drug-Lead Discovery Laboratory, Department of Chemistry and Biochemistry, Baylor University, One Bear Place, Waco, Texas 76798-7348, United States
| | - Daniel Romo
- Baylor Synthesis and Drug-Lead Discovery Laboratory, Department of Chemistry and Biochemistry, Baylor University, One Bear Place, Waco, Texas 76798-7348, United States
| | - Frank M Raushel
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, Texas 77843-2128, United States.,Department of Chemistry, Texas A&M University, 3255 TAMU, College Station, Texas 77843-3255, United States
| | - James C Sacchettini
- Department of Chemistry, Texas A&M University, 3255 TAMU, College Station, Texas 77843-3255, United States
| | - Margaret E Glasner
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, Texas 77843-2128, United States
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11
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Allen KN, Whitman CP. The Birth of Genomic Enzymology: Discovery of the Mechanistically Diverse Enolase Superfamily. Biochemistry 2021; 60:3515-3528. [PMID: 34664940 DOI: 10.1021/acs.biochem.1c00494] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Enzymes are categorized into superfamilies by sequence, structural, and mechanistic similarities. The evolutionary implications can be profound. Until the mid-1990s, the approach was fragmented largely due to limited sequence and structural data. However, in 1996, Babbitt et al. published a paper in Biochemistry that demonstrated the potential power of mechanistically diverse superfamilies to identify common ancestry, predict function, and, in some cases, predict specificity. This Perspective describes the findings of the original work and reviews the current understanding of structure and mechanism in the founding family members. The outcomes of the genomic enzymology approach have reached far beyond the functional assignment of members of the enolase superfamily, inspiring the study of superfamilies and the adoption of sequence similarity networks and genome context and yielding fundamental insights into enzyme evolution.
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Affiliation(s)
- Karen N Allen
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
| | - Christian P Whitman
- Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, The University of Texas at Austin, Austin, Texas 78712, United States
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12
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The β 2Tubulin, Rad50-ATPase and enolase cis-regulatory regions mediate male germline expression in Tribolium castaneum. Sci Rep 2021; 11:18131. [PMID: 34518617 PMCID: PMC8438054 DOI: 10.1038/s41598-021-97443-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 08/19/2021] [Indexed: 11/19/2022] Open
Abstract
Genetics-based pest management processes, including the sterile insect technique, are an effective method for the control of some pest insects. However, current SIT methods are not directly transferable to many important pest insect species due to the lack of genetic sexing strains. Genome editing is revolutionizing the way we conduct genetics in insects, including in Tribolium castaneum, an important genetic model and agricultural pest. We identified orthologues of β2Tubulin, Rad50-ATPase and enolase in T. castaneum. Using RT-PCR, we confirmed that these genes are predominantly expressed in the testis. PiggyBac-based transformation of T. castaneum cis-regulatory regions derived from Tc-β2t, Tc-rad50 or Tc-eno resulted in EGFP expression specifically in the T. castaneum testis. Additionally, we determined that each of these regulatory regions regulates EGFP expression in different cell types of the male gonad. Cis-regulatory regions from Tc-β2t produced EGFP expression throughout spermatogenesis and also in mature sperms; Tc-rad50 resulted in expression only in the haploid spermatid, while Tc-eno expressed EGFP in late spermatogenesis. In summary, the regulatory cis-regions characterized in this study are not only suited to study male gonadal function but could be used for development of transgenic sexing strains that produce one sex in pest control strategies.
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13
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Douglas CD, Grandinetti L, Easton NM, Kuehm OP, Hayden JA, Hamilton MC, St Maurice M, Bearne SL. Slow-Onset, Potent Inhibition of Mandelate Racemase by 2-Formylphenylboronic Acid. An Unexpected Adduct Clasps the Catalytic Machinery. Biochemistry 2021; 60:2508-2518. [PMID: 34339165 DOI: 10.1021/acs.biochem.1c00374] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
o-Carbonyl arylboronic acids such as 2-formylphenylboronic acid (2-FPBA) are employed in biocompatible conjugation reactions with the resulting iminoboronate adduct stabilized by an intramolecular N-B interaction. However, few studies have utilized these reagents as active site-directed enzyme inhibitors. We show that 2-FPBA is a potent reversible, slow-onset inhibitor of mandelate racemase (MR), an enzyme that has served as a valuable paradigm for understanding enzyme-catalyzed abstraction of an α-proton from a carbon acid substrate with a high pKa. Kinetic analysis of the progress curves for the slow onset of inhibition of wild-type MR using a two-step kinetic mechanism gave Ki and Ki* values of 5.1 ± 1.8 and 0.26 ± 0.08 μM, respectively. Hence, wild-type MR binds 2-FPBA with an affinity that exceeds that for the substrate by ∼3000-fold. K164R MR was inhibited by 2-FPBA, while K166R MR was not inhibited, indicating that Lys 166 was essential for inhibition. Unexpectedly, mass spectrometric analysis of the NaCNBH3-treated enzyme-inhibitor complex did not yield evidence of an iminoboronate adduct. 11B nuclear magnetic resonance spectroscopy of the MR·2-FPBA complex indicated that the boron atom was sp3-hybridized (δ 6.0), consistent with dative bond formation. Surprisingly, X-ray crystallography revealed the formation of an Nζ-B dative bond between Lys 166 and 2-FPBA with intramolecular cyclization to form a benzoxaborole, rather than the expected iminoboronate. Thus, when o-carbonyl arylboronic acid reagents are employed to modify proteins, the structure of the resulting product depends on the protein architecture at the site of modification.
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Affiliation(s)
- Colin D Douglas
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Lia Grandinetti
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin 53201-1881, United States
| | - Nicole M Easton
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Oliver P Kuehm
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Joshua A Hayden
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Meghan C Hamilton
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Martin St Maurice
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin 53201-1881, United States
| | - Stephen L Bearne
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
- Department of Chemistry, Dalhousie University, Halifax, NS B3H 4R2, Canada
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14
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Jeffery CJ, Dorgan KM, Pysh L. Promoting a more integrated approach to structure and function. Integr Comp Biol 2021; 61:2020-2030. [PMID: 34180524 DOI: 10.1093/icb/icab144] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The connection between structure and function is one of the fundamental tenets of biology: a biological unit's structure determines its function, and, conversely, its function depends upon its structure. Historically, important advances have been made either when understanding of structure leads to questions about function or when understanding of function raises questions about the structures involved. Consequently, considering the connections between structure and function from a broader perspective might lead to the development of novel hypotheses that move our understanding of the fundamental connections between structure and function forward. Better integration of structure and function is a key component in the broader goal of reintegrating biology within and across scales. Here, we provide examples of how integrating studies of structure and function as well as comparing structure-function relationships across biological scales can lead to scientific advances. We also emphasize the potential of integrating studies of structure and function across scales for bio-inspired design and for improving biology education.
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Affiliation(s)
- Constance J Jeffery
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA
| | | | - Leonard Pysh
- Biology Department, Roanoke College, Salem, VA, 24153, USA
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15
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Shimada T, Ogasawara H, Kobayashi I, Kobayashi N, Ishihama A. Single-Target Regulators Constitute the Minority Group of Transcription Factors in Escherichia coli K-12. Front Microbiol 2021; 12:697803. [PMID: 34220787 PMCID: PMC8249747 DOI: 10.3389/fmicb.2021.697803] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 05/28/2021] [Indexed: 11/13/2022] Open
Abstract
The identification of regulatory targets of all transcription factors (TFs) is critical for understanding the entire network of genome regulation. A total of approximately 300 TFs exist in the model prokaryote Escherichia coli K-12, but the identification of whole sets of their direct targets is impossible with use of in vivo approaches. For this end, the most direct and quick approach is to identify the TF-binding sites in vitro on the genome. We then developed and utilized the gSELEX screening system in vitro for identification of more than 150 E. coli TF-binding sites along the E. coli genome. Based on the number of predicted regulatory targets, we classified E. coli K-12 TFs into four groups, altogether forming a hierarchy ranging from a single-target TF (ST-TF) to local TFs, global TFs, and nucleoid-associated TFs controlling as many as 1,000 targets. Using the collection of purified TFs and a library of genome DNA segments from a single and the same E. coli K-12, we identified here a total of 11 novel ST-TFs, CsqR, CusR, HprR, NorR, PepA, PutA, QseA, RspR, UvrY, ZraR, and YqhC. The regulation of single-target promoters was analyzed in details for the hitherto uncharacterized QseA and RspR. In most cases, the ST-TF gene and its regulatory target genes are adjacently located on the E. coli K-12 genome, implying their simultaneous transfer in the course of genome evolution. The newly identified 11 ST-TFs and the total of 13 hitherto identified altogether constitute the minority group of TFs in E. coli K-12.
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Affiliation(s)
| | - Hiroshi Ogasawara
- Research Center for Supports to Advanced Science, Division of Gene Research, Shinshu University, Nagano, Japan.,Research Center for Fungal and Microbial Dynamism, Shinshu University, Nagano, Japan
| | - Ikki Kobayashi
- School of Agriculture, Meiji University, Kawasaki, Japan
| | - Naoki Kobayashi
- Department of Frontier Science, Hosei University, Koganei, Japan
| | - Akira Ishihama
- Department of Frontier Science, Hosei University, Koganei, Japan.,Micro-Nano Technology Research Center, Hosei University, Koganei, Japan
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16
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The Role of Enolases in Allergic Disease. THE JOURNAL OF ALLERGY AND CLINICAL IMMUNOLOGY-IN PRACTICE 2021; 9:3026-3032. [PMID: 33862268 DOI: 10.1016/j.jaip.2021.04.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 04/03/2021] [Accepted: 04/05/2021] [Indexed: 12/13/2022]
Abstract
Enolase is one of the most abundant cytosolic enzymes as well as an important glycolytic metalloenzyme highly conserved among organisms from different taxonomical groups. Participation of enolase in processes in which its enzymatic activity is not required has been widely reported. Some of these processes provide special qualities to microorganisms, which favor, in some cases, their pathogenicity. Remarkably, enolase has been reported as an allergen by itself, it is well recognized as allergenic in molds and yeasts, whereas it has also been recognized by the immune system of susceptible individuals acting as a food and inhaled allergen from other diverse sources such as insects, birds, fishes, and plants. To date, 14 enolases have been officially recognized by the World Health Organization/International Union of Immunological Societies Allergen Nomenclature Subcommittee. The use of discovery proteomics has also uncovered novel allergenic enolases, particularly from pollen sources. Here, we review the relevance of enolases as sensitizers and as nonsensitizing cross-reactive allergens in allergic disease.
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17
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Tästensen JB, Johnsen U, Reinhardt A, Ortjohann M, Schönheit P. D-galactose catabolism in archaea: operation of the DeLey-Doudoroff pathway in Haloferax volcanii. FEMS Microbiol Lett 2021; 367:5736015. [PMID: 32055827 DOI: 10.1093/femsle/fnaa029] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 02/11/2020] [Indexed: 11/12/2022] Open
Abstract
The haloarchaeon Haloferax volcanii was found to grow on D-galactose as carbon and energy source. Here we report a comprehensive analysis of D-galactose catabolism in H. volcanii. Genome analyses indicated a cluster of genes encoding putative enzymes of the DeLey-Doudoroff pathway for D-galactose degradation including galactose dehydrogenase, galactonate dehydratase, 2-keto-3-deoxygalactonate kinase and 2-keto-3-deoxy-6-phosphogalactonate (KDPGal) aldolase. The recombinant galactose dehydrogenase and galactonate dehydratase showed high specificity for D-galactose and galactonate, respectively, whereas KDPGal aldolase was promiscuous in utilizing KDPGal and also the C4 epimer 2-keto-3-deoxy-6-phosphogluconate as substrates. Growth studies with knock-out mutants indicated the functional involvement of galactose dehydrogenase, galactonate dehydratase and KDPGal aldolase in D-galactose degradation. Further, the transcriptional regulator GacR was identified, which was characterized as an activator of genes of the DeLey-Doudoroff pathway. Finally, genes were identified encoding components of an ABC transporter and a knock-out mutant of the substrate binding protein indicated the functional involvement of this transporter in D-galactose uptake. This is the first report of D-galactose degradation via the DeLey-Doudoroff pathway in the domain of archaea.
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Affiliation(s)
- Julia-Beate Tästensen
- Institut für Allgemeine Mikrobiologie, Christian-Albrechts-Universität Kiel, Am Botanischen Garten 1-9; D-24118 Kiel, Germany
| | - Ulrike Johnsen
- Institut für Allgemeine Mikrobiologie, Christian-Albrechts-Universität Kiel, Am Botanischen Garten 1-9; D-24118 Kiel, Germany
| | - Andreas Reinhardt
- Institut für Allgemeine Mikrobiologie, Christian-Albrechts-Universität Kiel, Am Botanischen Garten 1-9; D-24118 Kiel, Germany
| | - Marius Ortjohann
- Institut für Allgemeine Mikrobiologie, Christian-Albrechts-Universität Kiel, Am Botanischen Garten 1-9; D-24118 Kiel, Germany
| | - Peter Schönheit
- Institut für Allgemeine Mikrobiologie, Christian-Albrechts-Universität Kiel, Am Botanischen Garten 1-9; D-24118 Kiel, Germany
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18
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Abstract
The Embden–Meyerhof–Parnas (EMP) and Entner–Doudoroff (ED) pathways are considered the most abundant catabolic pathways found in microorganisms, and ED enzymes have been shown to also be widespread in cyanobacteria, algae and plants. In a large number of organisms, especially common strains used in molecular biology, these pathways account for the catabolism of glucose. The existence of pathways for other carbohydrates that are relevant to biomass utilization has been recognized as new strains have been characterized among thermophilic bacteria and Archaea that are able to transform simple polysaccharides from biomass to more complex and potentially valuable precursors for industrial microbiology. Many of the variants of the ED pathway have the key dehydratase enzyme involved in the oxidation of sugar derived from different families such as the enolase, IlvD/EDD and xylose-isomerase-like superfamilies. There are the variations in structure of proteins that have the same specificity and generally greater-than-expected substrate promiscuity. Typical biomass lignocellulose has an abundance of xylan, and four different pathways have been described, which include the Weimberg and Dahms pathways initially oxidizing xylose to xylono-gamma-lactone/xylonic acid, as well as the major xylose isomerase pathway. The recent realization that xylan constitutes a large proportion of biomass has generated interest in exploiting the compound for value-added precursors, but few chassis microorganisms can grow on xylose. Arabinose is part of lignocellulose biomass and can be metabolized with similar pathways to xylose, as well as an oxidative pathway. Like enzymes in many non-phosphorylative carbohydrate pathways, enzymes involved in L-arabinose pathways from bacteria and Archaea show metabolic and substrate promiscuity. A similar multiplicity of pathways was observed for other biomass-derived sugars such as L-rhamnose and L-fucose, but D-mannose appears to be distinct in that a non-phosphorylative version of the ED pathway has not been reported. Many bacteria and Archaea are able to grow on mannose but, as with other minor sugars, much of the information has been derived from whole cell studies with additional enzyme proteins being incorporated, and so far, only one synthetic pathway has been described. There appears to be a need for further discovery studies to clarify the general ability of many microorganisms to grow on the rarer sugars, as well as evaluation of the many gene copies displayed by marine bacteria.
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19
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Jeffery CJ. Enzymes, pseudoenzymes, and moonlighting proteins: diversity of function in protein superfamilies. FEBS J 2020; 287:4141-4149. [PMID: 32534477 DOI: 10.1111/febs.15446] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 03/20/2020] [Accepted: 06/08/2020] [Indexed: 12/31/2022]
Abstract
As more genome sequences are elucidated, there is an increasing need for information about the functions of the millions of proteins they encode. The function of a newly sequenced protein is often estimated by sequence alignment with the sequences of proteins with known functions. However, protein superfamilies can contain members that share significant amino acid sequence and structural homology yet catalyze different reactions or act on different substrates. Some homologous proteins differ by having a second or even third function, called moonlighting proteins. More recently, it was found that most protein superfamilies also include pseudoenzymes, a protein, or a domain within a protein, that has a three-dimensional fold that resembles a conventional catalytically active enzyme, but has no catalytic activity. In this review, we discuss several examples of protein families that contain enzymes, pseudoenzymes, and moonlighting proteins. It is becoming clear that pseudoenzymes and moonlighting proteins are widespread in the evolutionary tree, and in many protein families, and they are often very similar in sequence and structure to their monofunctional and catalytically active counterparts. A greater understanding is needed to clarify when similarities and differences in amino acid sequences and structures correspond to similarities and differences in biochemical functions and cellular roles. This information can help improve programs that identify protein functions from sequence or structure and assist in more accurate annotation of sequence and structural databases, as well as in our understanding of the broad diversity of protein functions.
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Affiliation(s)
- Constance J Jeffery
- Department of Biological Sciences, University of Illinois at Chicago, IL, USA
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20
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Pangenomics Analysis Reveals Diversification of Enzyme Families and Niche Specialization in Globally Abundant SAR202 Bacteria. mBio 2020; 11:mBio.02975-19. [PMID: 31911493 PMCID: PMC6946804 DOI: 10.1128/mbio.02975-19] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The oceans contain an estimated 662 Pg C in the form of dissolved organic matter (DOM). Information about microbial interactions with this vast resource is limited, despite broad recognition that DOM turnover has a major impact on the global carbon cycle. To explain patterns in the genomes of marine bacteria, we propose hypothetical metabolic pathways for the oxidation of organic molecules that are resistant to oxidation via common pathways. The hypothetical schemes we propose suggest new metabolic pathways and classes of compounds that could be important for understanding the distribution of organic carbon throughout the biosphere. These genome-based schemes will remain hypothetical until evidence from experimental cell biology can be gathered to test them. Our findings also fundamentally change our understanding of the ecology of SAR202 bacteria, showing that metabolically diverse variants of these cells occupy niches spanning all depths and are not relegated to the dark ocean. It has been hypothesized that the abundant heterotrophic ocean bacterioplankton in the SAR202 clade of the phylum Chloroflexi evolved specialized metabolisms for the oxidation of organic compounds that are resistant to microbial degradation via common metabolic pathways. Expansions of paralogous enzymes were reported and implicated in hypothetical metabolism involving monooxygenase and dioxygenase enzymes. In the proposed metabolic schemes, the paralogs serve the purpose of diversifying the range of organic molecules that cells can utilize. To further explore SAR202 evolution and metabolism, we reconstructed single amplified genomes and metagenome-assembled genomes from locations around the world that included the deepest ocean trenches. In an analysis of 122 SAR202 genomes that included seven subclades spanning SAR202 diversity, we observed additional evidence of paralog expansions that correlated with evolutionary history, as well as further evidence of metabolic specialization. Consistent with previous reports, families of flavin-dependent monooxygenases were observed mainly in the group III SAR202 genomes, and expansions of dioxygenase enzymes were prevalent in those of group VII. We found that group I SAR202 genomes encode expansions of racemases in the enolase superfamily, which we propose evolved for the degradation of compounds that resist biological oxidation because of chiral complexity. Supporting the conclusion that the paralog expansions indicate metabolic specialization, fragment recruitment and fluorescent in situ hybridization (FISH) with phylogenetic probes showed that SAR202 subclades are indigenous to different ocean depths and geographical regions. Surprisingly, some of the subclades were abundant in surface waters and contained rhodopsin genes, altering our understanding of the ecological role of SAR202 species in stratified water columns.
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21
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Holliday GL, Brown SD, Mischel D, Polacco BJ, Babbitt PC. A strategy for large-scale comparison of evolutionary- and reaction-based classifications of enzyme function. Database (Oxford) 2020; 2020:baaa034. [PMID: 32449511 PMCID: PMC7246345 DOI: 10.1093/database/baaa034] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 03/18/2020] [Accepted: 04/27/2020] [Indexed: 12/12/2022]
Abstract
Determining the molecular function of enzymes discovered by genome sequencing represents a primary foundation for understanding many aspects of biology. Historically, classification of enzyme reactions has used the enzyme nomenclature system developed to describe the overall reactions performed by biochemically characterized enzymes, irrespective of their associated sequences. In contrast, functional classification and assignment for the millions of protein sequences of unknown function now available is largely done in two computational steps, first by similarity-based assignment of newly obtained sequences to homologous groups, followed by transferring to them the known functions of similar biochemically characterized homologs. Due to the fundamental differences in their etiologies and practice, `how' these chemistry- and evolution-centric functional classification systems relate to each other has been difficult to explore on a large scale. To investigate this issue in a new way, we integrated two published ontologies that had previously described each of these classification systems independently. The resulting infrastructure was then used to compare the functional assignments obtained from each classification system for the well-studied and functionally diverse enolase superfamily. Mapping these function assignments to protein structure and reaction similarity networks shows a profound and complex disconnect between the homology- and chemistry-based classification systems. This conclusion mirrors previous observations suggesting that except for closely related sequences, facile annotation transfer from small numbers of characterized enzymes to the huge number uncharacterized homologs to which they are related is problematic. Our extension of these comparisons to large enzyme superfamilies in a computationally intelligent manner provides a foundation for new directions in protein function prediction for the huge proportion of sequences of unknown function represented in major databases. Interactive sequence, reaction, substrate and product similarity networks computed for this work for the enolase and two other superfamilies are freely available for download from the Structure Function Linkage Database Archive (http://sfld.rbvi.ucsf.edu).
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Affiliation(s)
- Gemma L Holliday
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, 1700 4th Street, CA 94143, USA
- Present Address: Medicines Discovery Catapult, Mereside, Alderley Park, Alderley Edge SK10 4TG, UK
| | - Shoshana D Brown
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, 1700 4th Street, CA 94143, USA
| | - David Mischel
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, 1700 4th Street, CA 94143, USA
| | - Benjamin J Polacco
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, 1700 4th Street, CA 94143, USA
| | - Patricia C Babbitt
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, 1700 4th Street, CA 94143, USA
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, 1700 4th Street, CA 94143, USA
- Quantitative Biosciences Institute, University of California, San Francisco, San Francisco, 1700 4th Street, CA 94143, USA
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22
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Oki K, Lee FS, Mayo SL. Attempts to develop an enzyme converting DHIV to KIV. Protein Eng Des Sel 2019; 32:261-270. [PMID: 31872250 DOI: 10.1093/protein/gzz042] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 10/01/2019] [Indexed: 11/13/2022] Open
Abstract
Dihydroxy-acid dehydratase (DHAD) catalyzes the dehydration of R-2,3-dihydroxyisovalerate (DHIV) to 2-ketoisovalerate (KIV) using an Fe-S cluster as a cofactor, which is sensitive to oxidation and expensive to synthesize. In contrast, sugar acid dehydratases catalyze the same chemical reactions using a magnesium ion. Here, we attempted to substitute the high-cost DHAD with a cost-efficient engineered sugar acid dehydratase using computational protein design (CPD). First, we tried without success to modify the binding pocket of a sugar acid dehydratase to accommodate the smaller, more hydrophobic DHIV. Then, we used a chemically activated substrate analog to react with sugar acid dehydratases or other enolase superfamily enzymes. Mandelate racemase from Pseudomonas putida (PpManR) and the putative sugar acid dehydratase from Salmonella typhimurium (StPutD) showed beta-elimination activity towards chlorolactate (CLD). CPD combined with medium-throughput selection improved the PpManR kcat/KM for CLD by four-fold. However, these enzyme variants did not show dehydration activity towards DHIV. Lastly, assuming phosphorylation could also be a good activation mechanism, we found that mevalonate-3-kinase (M3K) from Picrophilus torridus (PtM3K) exhibited adenosine triphosphate (ATP) hydrolysis activity when mixed with DHIV, indicating phosphorylation activity towards DHIV. Engineering PpManR or StPutD to accept 3-phospho-DHIV as a substrate was performed, but no variants with the desired activity were obtained.
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Affiliation(s)
- Kenji Oki
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., MC 114-96, Pasadena, CA 91125, USA.,Science & Innovation Center, Mitsubishi Chemical Corporation, Yokohama 227-8502, Japan
| | - Frederick S Lee
- Protabit LLC, 1010 Union St., Suite 110, Pasadena, CA 91101, USA
| | - Stephen L Mayo
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., MC 114-96, Pasadena, CA 91125, USA.,Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
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23
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Liu JH, Yang JY, Hsu DW, Lai YH, Li YP, Tsai YR, Hou MH. Crystal Structure-Based Exploration of Arginine-Containing Peptide Binding in the ADP-Ribosyltransferase Domain of the Type III Effector XopAI Protein. Int J Mol Sci 2019; 20:ijms20205085. [PMID: 31615004 PMCID: PMC6829252 DOI: 10.3390/ijms20205085] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 10/11/2019] [Accepted: 10/12/2019] [Indexed: 02/07/2023] Open
Abstract
Plant pathogens secrete proteins called effectors into the cells of their host to modulate the host immune response against colonization. Effectors can either modify or arrest host target proteins to sabotage the signaling pathway, and therefore are considered potential drug targets for crop disease control. In earlier research, the Xanthomonas type III effector XopAI was predicted to be a member of the arginine-specific mono-ADP-ribosyltransferase family. However, the crystal structure of XopAI revealed an altered active site that is unsuitable to bind the cofactor NAD+, but with the capability to capture an arginine-containing peptide from XopAI itself. The arginine peptide consists of residues 60 through 69 of XopAI, and residue 62 (R62) is key to determining the protein–peptide interaction. The crystal structure and the molecular dynamics simulation results indicate that specific arginine recognition is mediated by hydrogen bonds provided by the backbone oxygen atoms from residues W154, T155, and T156, and a salt bridge provided by the E265 sidechain. In addition, a protruding loop of XopAI adopts dynamic conformations in response to arginine peptide binding and is probably involved in target protein recognition. These data suggest that XopAI binds to its target protein by the peptide-binding ability, and therefore, it promotes disease progression. Our findings reveal an unexpected and intriguing function of XopAI and pave the way for further investigation on the role of XopAI in pathogen invasion.
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Affiliation(s)
- Jyung-Hurng Liu
- Institute of Genomics and Bioinformatics, National Chung Hsing University (NCHU), Taichung 40227, Taiwan.
- Department of Life Science, NCHU, Taichung 40227, Taiwan.
- Graduate Institute of Biotechnology, NCHU, Taichung 40227, Taiwan.
- PhD Program in Medical Biotechnology, NCHU, Taichung 40227, Taiwan.
| | - Jun-Yi Yang
- Graduate Institute of Biotechnology, NCHU, Taichung 40227, Taiwan.
- Graduate Institute of Biochemistry, NCHU, Taichung 40227, Taiwan.
| | - Duen-Wei Hsu
- Department of Biotechnology, National Kaohsiung Normal University, Kaohsiung 80201, Taiwan.
| | - Yi-Hua Lai
- Department of Life Science, NCHU, Taichung 40227, Taiwan.
| | - Yun-Pei Li
- Institute of Genomics and Bioinformatics, National Chung Hsing University (NCHU), Taichung 40227, Taiwan.
| | - Yi-Rung Tsai
- Institute of Genomics and Bioinformatics, National Chung Hsing University (NCHU), Taichung 40227, Taiwan.
| | - Ming-Hon Hou
- Institute of Genomics and Bioinformatics, National Chung Hsing University (NCHU), Taichung 40227, Taiwan.
- Department of Life Science, NCHU, Taichung 40227, Taiwan.
- Graduate Institute of Biotechnology, NCHU, Taichung 40227, Taiwan.
- PhD Program in Medical Biotechnology, NCHU, Taichung 40227, Taiwan.
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24
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Fetter CM, Morrison ZA, Nagar M, Douglas CD, Bearne SL. Altering the Y137-K164-K166 triad of mandelate racemase and its effect on the observed pK a of the Brønsted base catalysts. Arch Biochem Biophys 2019; 666:116-126. [PMID: 30935886 DOI: 10.1016/j.abb.2019.03.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 03/16/2019] [Accepted: 03/25/2019] [Indexed: 11/16/2022]
Abstract
Mandelate racemase (MR) catalyzes the interconversion of the enantiomers of mandelate using a two-base mechanism with Lys 166 acting as the Brønsted base to abstract the α-proton from (S)-mandelate. The resulting intermediate is subsequently re-protonated by the conjugate acid of His 297 to yield (R)-mandelate. The roles of these amino acids are reversed when (R)-mandelate is the substrate. The side chains of Tyr 137, Lys 164, and Lys 166 form a H-bonding network and the proximity of the two ε-NH3+ groups is believed to lower the pKa of Lys 166. We used site-directed mutagenesis, kinetics, and pH-rate studies to explore the roles of Lys 164 (K164 C/M) and Tyr 137 (Y137 L/F/S/T) in catalysis. The efficiency (kcat/Km) was reduced ∼3.5 × 105-fold for K164C MR, relative to wild-type MR, indicating a major role for this residue in catalysis. The efficiency of Y137F MR, however, was reduced only 25-30-fold. pH-Rate profiles (log kcat vs. pH) revealed that substitution of Tyr 137 by Phe increased the kinetic pKa of Lys 166 from 5.88 ± 0.02 to 7.3 ± 0.2. Hence, Tyr 137 plays an important role in facilitating the reduction of the pKa of the Brønsted base Lys 166 by ∼1.4 units. Interestingly, the Phe substitution also increased the kinetic pKa of His 297 from 5.97 ± 0.04 to 7.1 ± 0.1. Thus, the Tyr 137-Lys 164-Lys 166 H-bonding network plays a broader role in modulating the pKa of catalytic residues by influencing the electrostatic character of the entire active site, not only by decreasing the observed pKa value of Lys 166, but also by decreasing the pKa of His 297 by 1.1 units.
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Affiliation(s)
- Christopher M Fetter
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, B3H 4R2, Canada
| | - Zachary A Morrison
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, B3H 4R2, Canada
| | - Mitesh Nagar
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, B3H 4R2, Canada
| | - Colin D Douglas
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, B3H 4R2, Canada
| | - Stephen L Bearne
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, B3H 4R2, Canada; Department of Chemistry, Dalhousie University, Halifax, NS, B3H 4R2, Canada.
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25
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Nagar M, Kumar H, Bearne SL. A platform for chemical modification of mandelate racemase: characterization of the C92S/C264S and γ-thialysine 166 variants. Protein Eng Des Sel 2018; 31:135-145. [PMID: 29850884 DOI: 10.1093/protein/gzy011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 05/03/2018] [Indexed: 11/14/2022] Open
Abstract
Mandelate racemase (MR) serves as a paradigm for our understanding of enzyme-catalyzed deprotonation of a carbon acid substrate. To facilitate structure-function studies on MR using non-natural amino acid substitutions, we engineered the Cys92Ser/Cys264Ser variant (dmMR) as a platform for introducing Cys residues at specific locations for subsequent covalent modification. While the highly reactive thiol of Cys furnishes a site for chemical modification, site-specificity requires that other Cys residues be non-reactive or replaced by a non-reactive amino acid, especially if chemical modification is conducted under denaturing conditions. The catalytic efficiency of dmMR is reduced only ~2-fold relative to wild-type MR, making dmMR a viable platform for the site-specific introduction of Cys. As an example, the inactive Lys166Cys variant of dmMR was treated with ethylenimine under denaturing conditions to replace the Brønsted acid-base catalyst Lys 166 with the non-natural amino acid γ-thialysine. Comparison of the pH-activity profiles of dmMR and the active γ-thialysine variant revealed a reduction in the pKa for the side chain amino group of ~0.4 units for the latter variant. Unlike wild-type MR for which diffusion is partially rate-limiting, dmMR and the γ-thialysine variant showed no dependence on the solvent viscosity suggesting that the chemical step is fully rate-limiting.
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Affiliation(s)
- Mitesh Nagar
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, Canada
| | - Himank Kumar
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, Canada
| | - Stephen L Bearne
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, Canada.,Department of Chemistry, Dalhousie University, Halifax, NS, Canada
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QM/MM study of the reaction mechanism of Cl-cis,cis-muconate with muconate lactonizing enzyme. Bioorg Chem 2018; 80:453-460. [DOI: 10.1016/j.bioorg.2018.05.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 05/09/2018] [Accepted: 05/10/2018] [Indexed: 11/18/2022]
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27
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Odokonyero D, McMillan AW, Ramagopal UA, Toro R, Truong DP, Zhu M, Lopez MS, Somiari B, Herman M, Aziz A, Bonanno JB, Hull KG, Burley SK, Romo D, Almo SC, Glasner ME. Comparison of Alicyclobacillus acidocaldarius o-Succinylbenzoate Synthase to Its Promiscuous N-Succinylamino Acid Racemase/ o-Succinylbenzoate Synthase Relatives. Biochemistry 2018; 57:3676-3689. [PMID: 29767960 DOI: 10.1021/acs.biochem.8b00088] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Studying the evolution of catalytically promiscuous enzymes like those from the N-succinylamino acid racemase/ o-succinylbenzoate synthase (NSAR/OSBS) subfamily can reveal mechanisms by which new functions evolve. Some enzymes in this subfamily have only OSBS activity, while others catalyze OSBS and NSAR reactions. We characterized several NSAR/OSBS subfamily enzymes as a step toward determining the structural basis for evolving NSAR activity. Three enzymes were promiscuous, like most other characterized NSAR/OSBS subfamily enzymes. However, Alicyclobacillus acidocaldarius OSBS (AaOSBS) efficiently catalyzes OSBS activity but lacks detectable NSAR activity. Competitive inhibition and molecular modeling show that AaOSBS binds N-succinylphenylglycine with moderate affinity in a site that overlaps its normal substrate. On the basis of possible steric conflicts identified by molecular modeling and sequence conservation within the NSAR/OSBS subfamily, we identified one mutation, Y299I, that increased NSAR activity from undetectable to 1.2 × 102 M-1 s-1 without affecting OSBS activity. This mutation does not appear to affect binding affinity but instead affects kcat, by reorienting the substrate or modifying conformational changes to allow both catalytic lysines to access the proton that is moved during the reaction. This is the first site known to affect reaction specificity in the NSAR/OSBS subfamily. However, this gain of activity was obliterated by a second mutation, M18F. Epistatic interference by M18F was unexpected because a phenylalanine at this position is important in another NSAR/OSBS enzyme. Together, modest NSAR activity of Y299I AaOSBS and epistasis between sites 18 and 299 indicate that additional sites influenced the evolution of NSAR reaction specificity in the NSAR/OSBS subfamily.
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Affiliation(s)
- Denis Odokonyero
- Department of Biochemistry and Biophysics , Texas A&M University , 2128 TAMU , College Station , Texas 77843-2128 , United States
| | - Andrew W McMillan
- Department of Biochemistry and Biophysics , Texas A&M University , 2128 TAMU , College Station , Texas 77843-2128 , United States
| | | | | | - Dat P Truong
- Department of Biochemistry and Biophysics , Texas A&M University , 2128 TAMU , College Station , Texas 77843-2128 , United States
| | - Mingzhao Zhu
- CPRIT Synthesis and Drug-Lead Discovery Lab, Department of Chemistry and Biochemistry , Baylor University , One Bear Place , Waco , Texas 76798-7348 , United States
| | - Mariana S Lopez
- Department of Biochemistry and Biophysics , Texas A&M University , 2128 TAMU , College Station , Texas 77843-2128 , United States
| | - Belema Somiari
- Department of Biochemistry and Biophysics , Texas A&M University , 2128 TAMU , College Station , Texas 77843-2128 , United States
| | - Meghann Herman
- Department of Biochemistry and Biophysics , Texas A&M University , 2128 TAMU , College Station , Texas 77843-2128 , United States
| | - Asma Aziz
- Department of Biochemistry and Biophysics , Texas A&M University , 2128 TAMU , College Station , Texas 77843-2128 , United States
| | | | - Kenneth G Hull
- CPRIT Synthesis and Drug-Lead Discovery Lab, Department of Chemistry and Biochemistry , Baylor University , One Bear Place , Waco , Texas 76798-7348 , United States
| | - Stephen K Burley
- RCSB Protein Data Bank, Institute for Quantitative Biomedicine , Rutgers, The State University of New Jersey , Piscataway , New Jersey 08854-8076 , United States.,Rutgers Cancer Institute of New Jersey , New Brunswick , New Jersey 08903-2681 , United States
| | - Daniel Romo
- CPRIT Synthesis and Drug-Lead Discovery Lab, Department of Chemistry and Biochemistry , Baylor University , One Bear Place , Waco , Texas 76798-7348 , United States
| | | | - Margaret E Glasner
- Department of Biochemistry and Biophysics , Texas A&M University , 2128 TAMU , College Station , Texas 77843-2128 , United States
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28
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Affiliation(s)
- Jacquelyn S. Fetrow
- Office of the President, Albright College, Reading, Pennsylvania, United States of America
- * E-mail:
| | - Patricia C. Babbitt
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, United States of America
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29
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Bathellier C, Tcherkez G, Lorimer GH, Farquhar GD. Rubisco is not really so bad. PLANT, CELL & ENVIRONMENT 2018; 41:705-716. [PMID: 29359811 DOI: 10.1111/pce.13149] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 01/09/2018] [Accepted: 01/09/2018] [Indexed: 05/19/2023]
Abstract
Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is the most widespread carboxylating enzyme in autotrophic organisms. Its kinetic and structural properties have been intensively studied for more than half a century. Yet important aspects of the catalytic mechanism remain poorly understood, especially the oxygenase reaction. Because of its relatively modest turnover rate (a few catalytic events per second) and the competitive inhibition by oxygen, Rubisco is often viewed as an inefficient catalyst for CO2 fixation. Considerable efforts have been devoted to improving its catalytic efficiency, so far without success. In this review, we re-examine Rubisco's catalytic performance by comparison with other chemically related enzymes. We find that Rubisco is not especially slow. Furthermore, considering both the nature and the complexity of the chemical reaction, its kinetic properties are unremarkable. Although not unique to Rubisco, oxygenation is not systematically observed in enolate and enamine forming enzymes and cannot be considered as an inevitable consequence of the mechanism. It is more likely the result of a compromise between chemical and metabolic imperatives. We argue that a better description of Rubisco mechanism is still required to better understand the link between CO2 and O2 reactivity and the rationale of Rubisco diversification and evolution.
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Affiliation(s)
- Camille Bathellier
- Research School of Biology, College of Science, Australian National University, Canberra, 2601, ACT, Australia
| | - Guillaume Tcherkez
- Research School of Biology, College of Science, Australian National University, Canberra, 2601, ACT, Australia
| | - George H Lorimer
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD, 27042, USA
| | - Graham D Farquhar
- Research School of Biology, College of Science, Australian National University, Canberra, 2601, ACT, Australia
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30
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Easton NM, Aboushawareb SAE, Bearne SL. A continuous assay for l-talarate/galactarate dehydratase using circular dichroism. Anal Biochem 2017; 544:80-86. [PMID: 29248502 DOI: 10.1016/j.ab.2017.12.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 11/30/2017] [Accepted: 12/11/2017] [Indexed: 10/18/2022]
Abstract
l-Talarate/galactarate dehydratase (TGD) is a member of the enolase superfamily of enzymes and catalyzes the dehydration of either meso-galactarate or l-talarate to form 5-keto-4-deoxy-d-glucarate (5-KDG). To facilitate study of this enzyme and other galactarate dehydratases, a continuous circular dichroism-based assay has been developed. Using recombinant enzyme from Salmonella typhimurium (StTGD), the rates of StTGD-catalyzed conversion of m-galactarate to 5-KDG were determined by following the change in ellipticity at 323 nm. The apparent molar ellipticity ([θ]323) for the 5-KDG formed was determined to be 202 ± 2 deg cm2 dmol-1, which was used to convert observed rates (Δθ/Δt) into concentration-dependent rates (Δc/Δt). The kinetic parameters Km, kcat, and kcat/Km were 0.38 ± 0.05 mM, 4.8 ± 0.1 s-1, and 1.3 (±0.2) × 104 M-1s-1, respectively. These values are in excellent agreement with those published previously [Yew, W.S. et al. (2007) Biochemistry46, 9564-9577] using a coupled assay system. To demonstrate the utility of the assay, the inhibition constant (Ki = 10.7 ± 0.4 mM) was determined for the competitive inhibitor tartronate. The continuous CD-based assay offers a practical and efficient alternative method to the coupled assay that requires access to 5-KDG aldolase, and to the labor-intensive, fixed-time assays.
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Affiliation(s)
- Nicole M Easton
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Sarah A E Aboushawareb
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Stephen L Bearne
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada; Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada.
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31
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Lee S, Kim KH, Kim HY, Choi IG. Crystal structure analysis of 3,6-anhydro-l-galactonate cycloisomerase suggests emergence of novel substrate specificity in the enolase superfamily. Biochem Biophys Res Commun 2017; 491:217-222. [PMID: 28716734 DOI: 10.1016/j.bbrc.2017.07.080] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 07/03/2017] [Indexed: 12/01/2022]
Abstract
3,6-Anydro-l-galatonate cycloisomerase (ACI) catalyzes the cycloisomerization of a 3,6-anhydro-l-galactonic acid known as a novel metabolite in agarolytic bacteria. Here, we present 3-D structures of ACI from Vibrio sp. strain EJY3 (VejACI) in native and mutant forms at 2.2 Å and 2.6 Å resolutions, respectively. The enzyme belongs to the mandelate racemase subgroup of the enolase superfamily catalyzing common β-elimination reactions by α-carbon deprotonation of substrates. The structure of VejACI revealed a notable 20s loop region in the capping domain, which can be a highly conserved structural motif in ACI homologs of agar metabolism. By comparing mutant (mVejAC/H300 N) and native VejACI structures, we identified a conformational change of Ile142 in VejACI that causes spatial expansion in the binding pocket. These observations imply that Ile142 and the 20s loop play important roles in enzymatic reactivity and substrate specificity. The structural phylogenetic analysis of the enolase superfamily including ACIs revealed sequential, structural, and functional relationships related to the emergence of novel substrate specificity.
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Affiliation(s)
- Saeyoung Lee
- Department of Biotechnology, Korea University Graduate School, 5 Anam-ro, Seoungbuk-gu, Seoul, 02841, South Korea; Protein Structure Group, Korea Basic Science Institute, Ochang, Chungbuk, 28119, South Korea
| | - Kyoung Heon Kim
- Department of Biotechnology, Korea University Graduate School, 5 Anam-ro, Seoungbuk-gu, Seoul, 02841, South Korea
| | - Hye-Yeon Kim
- Protein Structure Group, Korea Basic Science Institute, Ochang, Chungbuk, 28119, South Korea; Department of Bio-Analytical Science, University of Science and Technology, Daejeon, 34133, South Korea; Center for Convergent Research of Emerging Virus Infection(CEVI), Korea Research Institute of Chemical Technology, Daejeon 34114, South Korea.
| | - In-Geol Choi
- Department of Biotechnology, Korea University Graduate School, 5 Anam-ro, Seoungbuk-gu, Seoul, 02841, South Korea.
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32
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Lee S, Yun EJ, Kim KH, Kim HY, Choi IG. 3,6-Anhydro-L-galactonate cycloisomerase from Vibrio sp. strain EJY3: crystallization and X-ray crystallographic analysis. Acta Crystallogr F Struct Biol Commun 2017; 73:511-514. [PMID: 28876229 PMCID: PMC5619742 DOI: 10.1107/s2053230x17011797] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 08/14/2017] [Indexed: 11/10/2022] Open
Abstract
3,6-Anhydro-L-galactonate cycloisomerase (ACI), which is found in the marine bacterium Vibrio sp. strain EJY3, converts 3,6-anhydro-L-galactonate into 2-keto-3-deoxygalactonate. ACI is a key enzyme in the metabolic pathway of 3,6-anhydro-L-galactose (AHG). Study of AHG metabolism is important for the efficient fermentation of agar and biofuel production, because AHG is a sugar that is non-fermentable by commercial microorganisms. The aci gene from Vibrio sp. strain EJY3 was cloned, and the recombinant protein was overexpressed and crystallized in order to determine the structure and understand the function of the protein. The crystals diffracted to 2.2 Å resolution and belonged to space group P41212 or P43212, with unit-cell parameters a = b = 87.9, c = 143.5 Å. The Matthews coefficient was 2.3 Å3 Da-1, with a solvent content of 47%.
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Affiliation(s)
- Saeyoung Lee
- Department of Biotechnology, Korea University Graduate School, Seoul 02841, Republic of Korea
| | - Eun Ju Yun
- Department of Biotechnology, Korea University Graduate School, Seoul 02841, Republic of Korea
| | - Kyoung Heon Kim
- Department of Biotechnology, Korea University Graduate School, Seoul 02841, Republic of Korea
| | - Hye-Yeon Kim
- Protein Structure Group, Korea Basic Science Institute, Ochang, Chungbuk 28119, Republic of Korea
- Department of Bio-Analytical Science, University of Science and Technology, Daejeon 34133, Republic of Korea
- Center for Convergent Research of Emerging Virus Infection (CEVI), Korea Research Institute of Chemical Technology, Daejeon 34114, Republic of Korea
| | - In-Geol Choi
- Department of Biotechnology, Korea University Graduate School, Seoul 02841, Republic of Korea
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33
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Bearne SL, St Maurice M. A Paradigm for CH Bond Cleavage: Structural and Functional Aspects of Transition State Stabilization by Mandelate Racemase. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2017; 109:113-160. [PMID: 28683916 DOI: 10.1016/bs.apcsb.2017.04.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Mandelate racemase (MR) from Pseudomonas putida catalyzes the Mg2+-dependent, 1,1-proton transfer reaction that racemizes (R)- and (S)-mandelate. MR shares a partial reaction (i.e., the metal ion-assisted, Brønsted base-catalyzed proton abstraction of the α-proton of carboxylic acid substrates) and structural features ((β/α)7β-barrel and N-terminal α + β capping domains) with a vast group of homologous, yet functionally diverse, enzymes in the enolase superfamily. Mechanistic and structural studies have developed this enzyme into a paradigm for understanding how enzymes such as those of the enolase superfamily overcome kinetic and thermodynamic barriers to catalyze the abstraction of an α-proton from a carbon acid substrate with a relatively high pKa value. Structural studies on MR bound to intermediate/transition state analogues have delineated those structural features that MR uses to stabilize transition states and enhance reaction rates of proton abstraction. Kinetic, site-directed mutagenesis, and structural studies have also revealed that the phenyl ring of the substrate migrates through the hydrophobic cavity within the active site during catalysis and that the Brønsted acid-base catalysts (Lys 166 and His 297) may be utilized as binding determinants for inhibitor recognition. In addition, structural studies on the adduct formed from the irreversible inhibition of MR by 3-hydroxypyruvate revealed that MR can form and deprotonate a Schiff-base with 3-hydroxypyruvate to yield an enol(ate)-aldehyde adduct, suggesting a possible evolutionary link between MR and the Schiff-base forming aldolases. As the archetype of the enolase superfamily, mechanistic and structural studies on MR will continue to enhance our understanding of enzyme catalysis and furnish insights into the evolution of enzyme function.
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34
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Goncalves P, Thompson EL, Raftos DA. Contrasting impacts of ocean acidification and warming on the molecular responses of CO 2-resilient oysters. BMC Genomics 2017; 18:431. [PMID: 28578697 PMCID: PMC5457604 DOI: 10.1186/s12864-017-3818-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 05/25/2017] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND This study characterises the molecular processes altered by both elevated CO2 and increasing temperature in oysters. Differences in resilience of marine organisms against the environmental stressors associated with climate change will have significant implications for the sustainability of coastal ecosystems worldwide. Some evidence suggests that climate change resilience can differ between populations within a species. B2 oysters represent a unique genetic resource because of their capacity to better withstand the impacts of elevated CO2 at the physiological level, compared to non-selected oysters from the same species (Saccostrea glomerata). Here, we used proteomic and transcriptomic analysis of gill tissue to evaluate whether the differential response of B2 oysters to elevated CO2 also extends to increased temperature. RESULTS Substantial and distinctive effects on protein concentrations and gene expression were evident among B2 oysters responding to elevated CO2 or elevated temperature. The combination of both stressors also altered oyster gill proteomes and gene expression. However, the impacts of elevated CO2 and temperature were not additive or synergistic, and may be antagonistic. CONCLUSIONS The data suggest that the simultaneous exposure of CO2-resilient oysters to near-future projected ocean pH and temperature results in complex changes in molecular processes in order to prevent stress-induced cellular damage. The differential response of B2 oysters to the combined stressors also indicates that the addition of thermal stress may impair the resilience of these oysters to decreased pH. Overall, this study reveals the intracellular mechanisms that might enable marine calcifiers to endure the emergent, adverse seawater conditions resulting from climate change.
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Affiliation(s)
- Priscila Goncalves
- Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia. .,Sydney Institute of Marine Science, Chowder Bay, Sydney, NSW, 2088, Australia.
| | - Emma L Thompson
- Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia.,Sydney Institute of Marine Science, Chowder Bay, Sydney, NSW, 2088, Australia.,Present Address: School of Life and Environmental Science, The University of Sydney, Sydney, NSW, 2006, Australia
| | - David A Raftos
- Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia.,Sydney Institute of Marine Science, Chowder Bay, Sydney, NSW, 2088, Australia
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35
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Sun C, Xu B, Liu X, Zhang Z, Su Z. Crystal structure of enolase from Drosophila melanogaster. Acta Crystallogr F Struct Biol Commun 2017; 73:228-234. [PMID: 28368282 PMCID: PMC5379173 DOI: 10.1107/s2053230x17004022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 03/13/2017] [Indexed: 11/10/2022] Open
Abstract
Enolase is an important enzyme in glycolysis and various biological processes. Its dysfunction is closely associated with diseases. Here, the enolase from Drosophila melanogaster (DmENO) was purified and crystallized. A crystal of DmENO diffracted to 2.0 Å resolution and belonged to space group R32. The structure was solved by molecular replacement. Like most enolases, DmENO forms a homodimer with conserved residues in the dimer interface. DmENO possesses an open conformation in this structure and contains conserved elements for catalytic activity. This work provides a structural basis for further functional and evolutionary studies of enolase.
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Affiliation(s)
- Congcong Sun
- College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao, Shandong 266042, People’s Republic of China
| | - Baokui Xu
- Jianghuai College, Anhui University, Hefei, Anhui 230039, People’s Republic of China
| | - Xueyan Liu
- College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao, Shandong 266042, People’s Republic of China
| | - Zhen Zhang
- Laboratory for TCM Immunopharmacology and Molecular Biology, Institute of Basic Medicine, Shandong Academy of Medical Sciences, 18877 Jingshi Road, Jinan, Shandong 250062, People’s Republic of China
| | - Zhongliang Su
- College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao, Shandong 266042, People’s Republic of China
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36
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Bearne SL. The interdigitating loop of the enolase superfamily as a specificity binding determinant or 'flying buttress'. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017; 1865:619-630. [PMID: 28179138 DOI: 10.1016/j.bbapap.2017.02.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 11/21/2016] [Accepted: 02/03/2017] [Indexed: 12/25/2022]
Abstract
BACKGROUND Enzymes of the enolase superfamily (ENS) are mechanistically diverse, yet share a common partial reaction (abstraction of the α-proton from a carboxylate substrate). While the catalytic machinery responsible for the deprotonation reaction has been conserved, divergent evolution has led to numerous ENS members that catalyze different overall reactions. This rich functional diversity has made the ENS an excellent model system for developing the approaches necessary to validate enzyme function. However, enzymes of the ENS also share a common bidomain structure ((β/α)7β-barrel domain and α+β capping domain) which makes validation of function from structural information challenging. SCOPE OF THE REVIEW This review presents a comparative survey of the structural data obtained over the past decade for enzymes from all seven subgroups that comprise the ENS. MAJOR CONCLUSIONS Of the seven ENS subgroups (enolase, mandelate racemase (MR), muconate lactonizing enzyme, β-methylaspartate ammonia lyase, d-glucarate dehydratase, d-mannonate dehydratase (ManD), and galactarate dehydratase 2), only enzymes of the MR and ManD subgroups exhibit an additional feature of structural complexity-an interdigitating loop. This loop emanates from one protomer of a homodimeric pair and penetrates into the adjacent, symmetry-related protomer to either contribute a binding determinant to the active site of the adjacent protomer, or act as a 'flying buttress' to support residues of the active site. GENERAL SIGNIFICANCE The analysis presented in this review suggests that the interdigitating loop is the only gross structural element that permits functional distinction between ENS subgroups at the tertiary level of protein structure.
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Affiliation(s)
- Stephen L Bearne
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, B3H 4R2, Canada; Department of Chemistry, Dalhousie University, Halifax, NS, B3H 4R2, Canada.
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37
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Sunden F, AlSadhan I, Lyubimov AY, Ressl S, Wiersma-Koch H, Borland J, Brown CL, Johnson TA, Singh Z, Herschlag D. Mechanistic and Evolutionary Insights from Comparative Enzymology of Phosphomonoesterases and Phosphodiesterases across the Alkaline Phosphatase Superfamily. J Am Chem Soc 2016; 138:14273-14287. [PMID: 27670607 PMCID: PMC5096464 DOI: 10.1021/jacs.6b06186] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Naively one might have expected an early division between phosphate monoesterases and diesterases of the alkaline phosphatase (AP) superfamily. On the contrary, prior results and our structural and biochemical analyses of phosphate monoesterase PafA, from Chryseobacterium meningosepticum, indicate similarities to a superfamily phosphate diesterase [Xanthomonas citri nucleotide pyrophosphatase/phosphodiesterase (NPP)] and distinct differences from the three metal ion AP superfamily monoesterase, from Escherichia coli AP (EcAP). We carried out a series of experiments to map out and learn from the differences and similarities between these enzymes. First, we asked why there would be independent instances of monoesterases in the AP superfamily? PafA has a much weaker product inhibition and slightly higher activity relative to EcAP, suggesting that different metabolic evolutionary pressures favored distinct active-site architectures. Next, we addressed the preferential phosphate monoester and diester catalysis of PafA and NPP, respectively. We asked whether the >80% sequence differences throughout these scaffolds provide functional specialization for each enzyme's cognate reaction. In contrast to expectations from this model, PafA and NPP mutants with the common subset of active-site groups embedded in each native scaffold had the same monoesterase:diesterase specificities; thus, the >107-fold difference in native specificities appears to arise from distinct interactions at a single phosphoryl substituent. We also uncovered striking mechanistic similarities between the PafA and EcAP monoesterases, including evidence for ground-state destabilization and functional active-site networks that involve different active-site groups but may play analogous catalytic roles. Discovering common network functions may reveal active-site architectural connections that are critical for function, and identifying regions of functional modularity may facilitate the design of new enzymes from existing promiscuous templates. More generally, comparative enzymology and analysis of catalytic promiscuity can provide mechanistic and evolutionary insights.
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Affiliation(s)
- Fanny Sunden
- Department of Biochemistry, Beckman Center, Stanford University , Stanford, California 94305, United States
| | - Ishraq AlSadhan
- Department of Biochemistry, Beckman Center, Stanford University , Stanford, California 94305, United States
| | - Artem Y Lyubimov
- Departments of Molecular and Cellular Physiology, Neurology and Neurological Science, Structural Biology, and Photon Science, Howard Hughes Medical Institute, Stanford University , Stanford, California 94305, United States
| | - Susanne Ressl
- Molecular and Cellular Biochemistry Department, Indiana University , Bloomington, Indiana 47405, United States
| | - Helen Wiersma-Koch
- Department of Biochemistry, Beckman Center, Stanford University , Stanford, California 94305, United States.,Department of Biology, Indian River State College , Fort Pierce, Florida 34981, United States
| | - Jamar Borland
- Department of Biochemistry, Beckman Center, Stanford University , Stanford, California 94305, United States
| | - Clayton L Brown
- Department of Biochemistry, Beckman Center, Stanford University , Stanford, California 94305, United States
| | - Tory A Johnson
- Department of Biochemistry, Beckman Center, Stanford University , Stanford, California 94305, United States
| | - Zorawar Singh
- Department of Biochemistry, Beckman Center, Stanford University , Stanford, California 94305, United States
| | - Daniel Herschlag
- Department of Biochemistry, Beckman Center, Stanford University , Stanford, California 94305, United States.,Departments of Chemical Engineering and Chemistry, and Stanford ChEM-H (Chemistry, Engineering, and Medicine for Human Health), Stanford University , Stanford, California 94305, United States
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38
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Leonard PG, Satani N, Maxwell D, Lin YH, Hammoudi N, Peng Z, Pisaneschi F, Link TM, Lee GR, Sun D, Prasad BAB, Di Francesco ME, Czako B, Asara JM, Wang YA, Bornmann W, DePinho RA, Muller FL. SF2312 is a natural phosphonate inhibitor of enolase. Nat Chem Biol 2016; 12:1053-1058. [PMID: 27723749 PMCID: PMC5110371 DOI: 10.1038/nchembio.2195] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 08/02/2016] [Indexed: 12/28/2022]
Abstract
Despite being critical for energy generation in most forms of life, few if any microbial antibiotics specifically inhibit glycolysis. To develop a specific inhibitor of the glycolytic enzyme Enolase 2 for the treatment of cancers with deletion of Enolase 1, we modeled the synthetic tool compound inhibitor, Phosphonoacetohydroxamate (PhAH) into the active site of human ENO2. A ring-stabilized analogue of PhAH, with the hydroxamic nitrogen linked to the alpha-carbon by an ethylene bridge, was predicted to increase binding affinity by stabilizing the inhibitor in a bound conformation. Unexpectedly, a structure based search revealed that our hypothesized back-bone-stabilized PhAH bears strong similarity to SF2312, a phosphonate antibiotic of unknown mode of action produced by the actinomycete Micromonospora, which is active under anaerobic conditions. Here, we present multiple lines of evidence, including a novel X-ray structure, that SF2312 is a highly potent, low nM inhibitor of Enolase.
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Affiliation(s)
- Paul G Leonard
- Department of Genomic Medicine and Core for Biomolecular Structure and Function, University of Texas MD Anderson Cancer Center, Houston, TX 77054
| | - Nikunj Satani
- Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, TX 77054
| | - David Maxwell
- Department of Clinical Analytics & Informatics, Houston, TX 77054-3403
| | - Yu-Hsi Lin
- Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, TX 77054
| | - Naima Hammoudi
- Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, TX 77054
| | | | - Federica Pisaneschi
- Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, TX 77054
| | - Todd M Link
- Department of Genomic Medicine and Core for Biomolecular Structure and Function, University of Texas MD Anderson Cancer Center, Houston, TX 77054
| | - Gilbert R Lee
- Department of Genomic Medicine and Core for Biomolecular Structure and Function, University of Texas MD Anderson Cancer Center, Houston, TX 77054
| | - Duoli Sun
- Department of Genomic Medicine and Core for Biomolecular Structure and Function, University of Texas MD Anderson Cancer Center, Houston, TX 77054
| | - Basvoju A Bhanu Prasad
- Department of Genomic Medicine and Core for Biomolecular Structure and Function, University of Texas MD Anderson Cancer Center, Houston, TX 77054
| | - Maria Emilia Di Francesco
- Institute for Applied Cancer Science, University of Texas MD Anderson Cancer Center, Houston, TX 77054
| | - Barbara Czako
- Institute for Applied Cancer Science, University of Texas MD Anderson Cancer Center, Houston, TX 77054
| | - John M Asara
- Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02115
| | - Y Alan Wang
- Department of Cancer Biology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA University of Texas MD Anderson Cancer Center, Houston, TX 77054 USA
| | | | - Ronald A DePinho
- Department of Cancer Biology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA University of Texas MD Anderson Cancer Center, Houston, TX 77054 USA
| | - Florian L Muller
- Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, TX 77054
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Key Enzymes of the Semiphosphorylative Entner-Doudoroff Pathway in the Haloarchaeon Haloferax volcanii: Characterization of Glucose Dehydrogenase, Gluconate Dehydratase, and 2-Keto-3-Deoxy-6-Phosphogluconate Aldolase. J Bacteriol 2016; 198:2251-62. [PMID: 27297879 DOI: 10.1128/jb.00286-16] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 06/06/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The halophilic archaeon Haloferax volcanii has been proposed to degrade glucose via the semiphosphorylative Entner-Doudoroff (spED) pathway. So far, the key enzymes of this pathway, glucose dehydrogenase (GDH), gluconate dehydratase (GAD), and 2-keto-3-deoxy-6-phosphogluconate (KDPG) aldolase (KDPGA), have not been characterized, and their functional involvement in glucose degradation has not been demonstrated. Here we report that the genes HVO_1083 and HVO_0950 encode GDH and KDPGA, respectively. The recombinant enzymes show high specificity for glucose and KDPG and did not convert the corresponding C4 epimers galactose and 2-keto-3-deoxy-6-phosphogalactonate at significant rates. Growth studies of knockout mutants indicate the functional involvement of both GDH and KDPGA in glucose degradation. GAD was purified from H. volcanii, and the encoding gene, gad, was identified as HVO_1488. GAD catalyzed the specific dehydration of gluconate and did not utilize galactonate at significant rates. A knockout mutant of GAD lost the ability to grow on glucose, indicating the essential involvement of GAD in glucose degradation. However, following a prolonged incubation period, growth of the Δgad mutant on glucose was recovered. Evidence is presented that under these conditions, GAD was functionally replaced by xylonate dehydratase (XAD), which uses both xylonate and gluconate as substrates. Together, the characterization of key enzymes and analyses of the respective knockout mutants present conclusive evidence for the in vivo operation of the spED pathway for glucose degradation in H. volcanii IMPORTANCE The work presented here describes the identification and characterization of the key enzymes glucose dehydrogenase, gluconate dehydratase, and 2-keto-3-deoxy-6-phosphogluconate aldolase and their encoding genes of the proposed semiphosphorylative Entner-Doudoroff pathway in the haloarchaeon Haloferax volcanii The functional involvement of the three enzymes was proven by analyses of the corresponding knockout mutants. These results provide evidence for the in vivo operation of the semiphosphorylative Entner-Doudoroff pathway in haloarchaea and thus expand our understanding of the unusual sugar degradation pathways in the domain Archaea.
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Guo X, Pei J, Ding X, Chu M, Bao P, Wu X, Liang C, Yan P. Comparative Proteomic Analysis of Yak Follicular Fluid during Estrus. ASIAN-AUSTRALASIAN JOURNAL OF ANIMAL SCIENCES 2016; 29:1239-46. [PMID: 26954118 PMCID: PMC5003983 DOI: 10.5713/ajas.15.0724] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 11/09/2015] [Accepted: 12/18/2015] [Indexed: 01/02/2023]
Abstract
The breeding of yaks is highly seasonal, there are many crucial proteins involved in the reproduction control program, especially in follicular development. In order to isolate differential proteins between mature and immature follicular fluid (FF) of yak, the FF from yak follicles with different sizes were sampled respectively, and two-dimensional gel electrophoresis (2-DE) of the proteins was carried out. After silver staining, the Image Master 2D platinum software was used for protein analysis and matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS) was performed for differential protein identification. The expression level of transferrin and enolase superfamily member 1 (ENOSF1) was determined by Western blotting for verification analysis. The results showed that 2-DE obtained an electrophoresis map of proteins from mature and immature yak FF with high resolution and repeatability. A comparison of protein profiles identified 12 differently expressed proteins, out of which 10 of them were upregulated while 2 were downregulated. Western blotting showed that the expression of transferrin and ENOSF1 was enhanced with follicular development. Both the obtained protein profiles and the differently expressed proteins identified in this study provided experimental data related to follicular development during yak breeding seasons. This study also laid the foundation for understanding the microenvironment during oocyte development.
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Affiliation(s)
- Xian Guo
- Key Laboratory of Yak Breeding Engineering of Gansu Province, Lanzhou Institute of Husbandry and Pharmaceutical Sciences, Chinese Academy of Agricultural Sciences, Lanzhou 730050, China
| | - Jie Pei
- Key Laboratory of Yak Breeding Engineering of Gansu Province, Lanzhou Institute of Husbandry and Pharmaceutical Sciences, Chinese Academy of Agricultural Sciences, Lanzhou 730050, China
| | - Xuezhi Ding
- Key Laboratory of Yak Breeding Engineering of Gansu Province, Lanzhou Institute of Husbandry and Pharmaceutical Sciences, Chinese Academy of Agricultural Sciences, Lanzhou 730050, China
| | - Min Chu
- Key Laboratory of Yak Breeding Engineering of Gansu Province, Lanzhou Institute of Husbandry and Pharmaceutical Sciences, Chinese Academy of Agricultural Sciences, Lanzhou 730050, China
| | - Pengjia Bao
- Key Laboratory of Yak Breeding Engineering of Gansu Province, Lanzhou Institute of Husbandry and Pharmaceutical Sciences, Chinese Academy of Agricultural Sciences, Lanzhou 730050, China
| | - Xiaoyun Wu
- Key Laboratory of Yak Breeding Engineering of Gansu Province, Lanzhou Institute of Husbandry and Pharmaceutical Sciences, Chinese Academy of Agricultural Sciences, Lanzhou 730050, China
| | - Chunnian Liang
- Key Laboratory of Yak Breeding Engineering of Gansu Province, Lanzhou Institute of Husbandry and Pharmaceutical Sciences, Chinese Academy of Agricultural Sciences, Lanzhou 730050, China
| | - Ping Yan
- Key Laboratory of Yak Breeding Engineering of Gansu Province, Lanzhou Institute of Husbandry and Pharmaceutical Sciences, Chinese Academy of Agricultural Sciences, Lanzhou 730050, China
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Rauwerdink A, Lunzer M, Devamani T, Jones B, Mooney J, Zhang ZJ, Xu JH, Kazlauskas RJ, Dean AM. Evolution of a Catalytic Mechanism. Mol Biol Evol 2015; 33:971-9. [PMID: 26681154 DOI: 10.1093/molbev/msv338] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The means by which superfamilies of specialized enzymes arise by gene duplication and functional divergence are poorly understood. The escape from adaptive conflict hypothesis, which posits multiple copies of a gene encoding a primitive inefficient and highly promiscuous generalist ancestor, receives support from experiments showing that resurrected ancestral enzymes are indeed more substrate-promiscuous than their modern descendants. Here, we provide evidence in support of an alternative model, the innovation-amplification-divergence hypothesis, which posits a single-copied ancestor as efficient and specific as any modern enzyme. We argue that the catalytic mechanisms of plant esterases and descendent acetone cyanohydrin lyases are incompatible with each other (e.g., the reactive substrate carbonyl must bind in opposite orientations in the active site). We then show that resurrected ancestral plant esterases are as catalytically specific as modern esterases, that the ancestor of modern acetone cyanohydrin lyases was itself only very weakly promiscuous, and that improvements in lyase activity came at the expense of esterase activity. These observations support the innovation-amplification-divergence hypothesis, in which an ancestor gains a weak promiscuous activity that is improved by selection at the expense of the ancestral activity, and not the escape from adaptive conflict in which an inefficient generalist ancestral enzyme steadily loses promiscuity throughout the transition to a highly active specialized modern enzyme.
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Affiliation(s)
- Alissa Rauwerdink
- Department of Biochemistry, Molecular Biology & Biophysics and the Biotechnology Institute, University of Minnesota
| | - Mark Lunzer
- Department of Biochemistry, Molecular Biology & Biophysics and the Biotechnology Institute, University of Minnesota
| | - Titu Devamani
- Department of Biochemistry, Molecular Biology & Biophysics and the Biotechnology Institute, University of Minnesota
| | - Bryan Jones
- Department of Biochemistry, Molecular Biology & Biophysics and the Biotechnology Institute, University of Minnesota
| | - Joanna Mooney
- Department of Biochemistry, Molecular Biology & Biophysics and the Biotechnology Institute, University of Minnesota
| | - Zhi-Jun Zhang
- Department of Biochemistry, Molecular Biology & Biophysics and the Biotechnology Institute, University of Minnesota Department of Biotechnology, East China University of Science and Technology, Shanghai, PR China
| | - Jian-He Xu
- Department of Biochemistry, Molecular Biology & Biophysics and the Biotechnology Institute, University of Minnesota Department of Biotechnology, East China University of Science and Technology, Shanghai, PR China
| | - Romas J Kazlauskas
- Department of Biochemistry, Molecular Biology & Biophysics and the Biotechnology Institute, University of Minnesota
| | - Antony M Dean
- Department of Biochemistry, Molecular Biology & Biophysics and the Biotechnology Institute, University of Minnesota Department of Ecology, Evolution and Behavior, University of Minnesota College of Ecology and Evolution, Sun Yat-Sen University, Guangzhou, PR China
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Wu Y, Wang C, Lin S, Wu M, Han L, Tian C, Zhang X, Zang J. Octameric structure of Staphylococcus aureus enolase in complex with phosphoenolpyruvate. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2015; 71:2457-70. [PMID: 26627653 PMCID: PMC4667285 DOI: 10.1107/s1399004715018830] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 10/07/2015] [Indexed: 12/31/2022]
Abstract
Staphylococcus aureus is a Gram-positive bacterium with strong pathogenicity that causes a wide range of infections and diseases. Enolase is an evolutionarily conserved enzyme that plays a key role in energy production through glycolysis. Additionally, enolase is located on the surface of S. aureus and is involved in processes leading to infection. Here, crystal structures of Sa_enolase with and without bound phosphoenolpyruvate (PEP) are presented at 1.6 and 2.45 Å resolution, respectively. The structure reveals an octameric arrangement; however, both dimeric and octameric conformations were observed in solution. Furthermore, enzyme-activity assays show that only the octameric variant is catalytically active. Biochemical and structural studies indicate that the octameric form of Sa_enolase is enzymatically active in vitro and likely also in vivo, while the dimeric form is catalytically inactive and may be involved in other biological processes.
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Affiliation(s)
- Yunfei Wu
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, Collaborative Innovation Center of Chemistry for Life Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, People’s Republic of China
- Key Laboratory of Structural Biology, Chinese Academy of Sciences, Hefei, Anhui 230027, People’s Republic of China
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230027, People’s Republic of China
| | - Chengliang Wang
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, Collaborative Innovation Center of Chemistry for Life Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, People’s Republic of China
- Key Laboratory of Structural Biology, Chinese Academy of Sciences, Hefei, Anhui 230027, People’s Republic of China
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230027, People’s Republic of China
| | - Shenglong Lin
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, Collaborative Innovation Center of Chemistry for Life Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, People’s Republic of China
- Key Laboratory of Structural Biology, Chinese Academy of Sciences, Hefei, Anhui 230027, People’s Republic of China
- High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, People’s Republic of China
| | - Minhao Wu
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, Collaborative Innovation Center of Chemistry for Life Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, People’s Republic of China
- Key Laboratory of Structural Biology, Chinese Academy of Sciences, Hefei, Anhui 230027, People’s Republic of China
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230027, People’s Republic of China
| | - Lu Han
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, Collaborative Innovation Center of Chemistry for Life Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, People’s Republic of China
- Key Laboratory of Structural Biology, Chinese Academy of Sciences, Hefei, Anhui 230027, People’s Republic of China
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230027, People’s Republic of China
| | - Changlin Tian
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, Collaborative Innovation Center of Chemistry for Life Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, People’s Republic of China
- Key Laboratory of Structural Biology, Chinese Academy of Sciences, Hefei, Anhui 230027, People’s Republic of China
- High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, People’s Republic of China
| | - Xuan Zhang
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, Collaborative Innovation Center of Chemistry for Life Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, People’s Republic of China
- Key Laboratory of Structural Biology, Chinese Academy of Sciences, Hefei, Anhui 230027, People’s Republic of China
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230027, People’s Republic of China
| | - Jianye Zang
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, Collaborative Innovation Center of Chemistry for Life Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, People’s Republic of China
- Key Laboratory of Structural Biology, Chinese Academy of Sciences, Hefei, Anhui 230027, People’s Republic of China
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230027, People’s Republic of China
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Nagar M, Bearne SL. An additional role for the Brønsted acid-base catalysts of mandelate racemase in transition state stabilization. Biochemistry 2015; 54:6743-52. [PMID: 26480244 DOI: 10.1021/acs.biochem.5b00982] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mandelate racemase (MR) catalyzes the interconversion of the enantiomers of mandelate and serves as a paradigm for understanding the enzyme-catalyzed abstraction of an α-proton from a carbon acid substrate with a high pKa. The enzyme utilizes a two-base mechanism with Lys 166 and His 297 acting as Brønsted acid and base catalysts, respectively, in the R → S reaction direction. In the S → R reaction direction, their roles are reversed. Using isothermal titration calorimetry (ITC), MR is shown to bind the intermediate/transition state (TS) analogue inhibitor benzohydroxamate (BzH) in an entropy-driven process with a value of ΔCp equal to -358 ± 3 cal mol(-1) K(-1), consistent with an increased number of hydrophobic interactions. However, MR binds BzH with an affinity that is ∼2 orders of magnitude greater than that predicted solely on the basis of hydrophobic interactions [St. Maurice, M., and Bearne, S. L. (2004) Biochemistry 43, 2524], suggesting that additional specific interactions contribute to binding. To test the hypothesis that cation-π/NH-π interactions between the side chains of Lys 166 and His 297 and the aromatic ring and/or the hydroxamate/hydroximate moiety of BzH contribute to the binding of BzH, site-directed mutagenesis was used to generate the MR variants K166M, K166C, H297N, and K166M/H297N and their binding affinity for various ligands determined using ITC. Comparison of the binding affinities of these MR variants with the intermediate/TS analogues BzH and cyclohexanecarbohydroxamate revealed that cation-π/NH-π interactions between His 297 and the hydroxamate/hydroximate moiety and the phenyl ring of BzH contribute approximately 0.26 and 0.91 kcal/mol to binding, respectively, while interactions with Lys 166 contribute approximately 1.74 and 1.74 kcal/mol, respectively. Similarly, comparison of the binding affinities of these mutants with substrate analogues revealed that Lys 166 contributes >2.93 kcal/mol to the binding of (R)-atrolactate, and His 297 contributes 2.46 kcal/mol to the binding of (S)-atrolactate. These results are consistent with Lys 166 and His 297 playing dual roles in catalysis: they act as Brønsted acid-base catalysts, and they stabilize both the enolate moiety and phenyl ring of the altered substrate in the TS.
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Affiliation(s)
- Mitesh Nagar
- Department of Biochemistry and Molecular Biology, Dalhousie University , Halifax, NS B3H 4R2, Canada
| | - Stephen L Bearne
- Department of Biochemistry and Molecular Biology, Dalhousie University , Halifax, NS B3H 4R2, Canada.,Department of Chemistry, Dalhousie University , Halifax, NS B3H 4R2, Canada
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Abstract
Escherichia coli and Salmonella contain the naphthoquinones menaquinone (MK; vitamin K2) and demethylmenaquinone and the benzoquinone ubiquinone (coenzyme Q; Q). Both quinones are derived from the shikimate pathway, which has been called a "metabolic tree with many branches." There are two different pathways for the biosynthesis of the naphthoquinones. The vast majority of prokaryotes, including E. coli and Salmonella, and the plants use the o-succinylbenzoate pathway, while a minority uses the futalosine pathway. The quinone nucleus of Q is derived directly from chorismate, while that of MK is derived from chorismate via isochorismate. The prenyl side chains of both quinones are from isopentenyl diphosphate formed by the 2-C-methyl-D-erythritol 4-phosphate (non-mevalonate) pathway and the methyl groups are from S-adenosylmethionine. In addition, MK biosynthesis requires 2-ketoglutarate and cofactors ATP, coenzyme A, and thiamine pyrophosphate. Despite the fact that both quinones originate from the shikimate pathway, there are important differences in their biosyntheses. The prenyl side chain in MK biosynthesis is introduced at the penultimate step, accompanied by decarboxylation, whereas in Q biosynthesis it is introduced at the second step, with retention of the carboxyl group. In MK biosynthesis, all the reactions of the pathway up to prenylation are carried out by soluble enzymes, whereas all the enzymes involved in Q biosynthesis except the first are membrane bound. In MK biosynthesis, the last step is a C-methylation; in Q biosynthesis, the last step is an O-methylation. In Q biosynthesis a second C-methylation and O-methylation take place in the middle part of the pathway. Despite the fact that Q and MK biosyntheses diverge at chorismate, the C-methylations in both pathways are carried out by the same methyltransferase.
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Cho SJ, Kim JA, Lee SB. Identification and characterization of 3,6-anhydro-L-galactonate cycloisomerase belonging to theenolase superfamily. BIOTECHNOL BIOPROC E 2015. [DOI: 10.1007/s12257-015-0359-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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46
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When Too Much ATP Is Bad for Protein Synthesis. J Mol Biol 2015; 427:2586-2594. [PMID: 26150063 DOI: 10.1016/j.jmb.2015.06.021] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Revised: 06/30/2015] [Accepted: 06/30/2015] [Indexed: 01/17/2023]
Abstract
Adenosine triphosphate (ATP) is the energy currency of living cells. Even though ATP powers virtually all energy-dependent activities, most cellular ATP is utilized in protein synthesis via tRNA aminoacylation and guanosine triphosphate regeneration. Magnesium (Mg(2+)), the most common divalent cation in living cells, plays crucial roles in protein synthesis by maintaining the structure of ribosomes, participating in the biochemistry of translation initiation and functioning as a counterion for ATP. A non-physiological increase in ATP levels hinders growth in cells experiencing Mg(2+) limitation because ATP is the most abundant nucleotide triphosphate in the cell, and Mg(2+) is also required for the stabilization of the cytoplasmic membrane and as a cofactor for essential enzymes. We propose that organisms cope with Mg(2+) limitation by decreasing ATP levels and ribosome production, thereby reallocating Mg(2+) to indispensable cellular processes.
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47
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Zadvornyy OA, Boyd ES, Posewitz MC, Zorin NA, Peters JW. Biochemical and Structural Characterization of Enolase from Chloroflexus aurantiacus: Evidence for a Thermophilic Origin. Front Bioeng Biotechnol 2015; 3:74. [PMID: 26082925 PMCID: PMC4450660 DOI: 10.3389/fbioe.2015.00074] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 05/08/2015] [Indexed: 11/13/2022] Open
Abstract
Enolase catalyzes the conversion of 2-phosphoglycerate to phosphoenolpyruvate during both glycolysis and gluconeogenesis, and is required by all three domains of life. Here, we report the purification and biochemical and structural characterization of enolase from Chloroflexus aurantiacus, a thermophilic anoxygenic phototroph affiliated with the green non-sulfur bacteria. The protein was purified as a homodimer with a subunit molecular weight of 46 kDa. The temperature optimum for enolase catalysis was 80°C, close to the measured thermal stability of the protein which was determined to be 75°C, while the pH optimum for enzyme activity was 6.5. The specific activities of purified enolase determined at 25 and 80°C were 147 and 300 U mg(-1) of protein, respectively. K m values for the 2-phosphoglycerate/phosphoenolpyruvate reaction determined at 25 and 80°C were 0.16 and 0.03 mM, respectively. The K m values for Mg(2+) binding at these temperatures were 2.5 and 1.9 mM, respectively. When compared to enolase from mesophiles, the biochemical and structural properties of enolase from C. aurantiacus are consistent with this being thermally adapted. These data are consistent with the results of our phylogenetic analysis of enolase, which reveal that enolase has a thermophilic origin.
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Affiliation(s)
- Oleg A Zadvornyy
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, MT , USA ; Institute of Basic Biological Problems, Russian Academy of Sciences , Pushchino , Russia
| | - Eric S Boyd
- Department of Microbiology and Immunology, Montana State University , Bozeman, MT , USA
| | - Matthew C Posewitz
- Department of Chemistry and Geochemistry, Colorado School of Mines , Golden, CO , USA
| | - Nikolay A Zorin
- Institute of Basic Biological Problems, Russian Academy of Sciences , Pushchino , Russia
| | - John W Peters
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, MT , USA
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Nagar M, Wyatt BN, St Maurice M, Bearne SL. Inactivation of Mandelate Racemase by 3-Hydroxypyruvate Reveals a Potential Mechanistic Link between Enzyme Superfamilies. Biochemistry 2015; 54:2747-57. [PMID: 25844917 DOI: 10.1021/acs.biochem.5b00221] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mandelate racemase (MR), a member of the enolase superfamily, catalyzes the Mg(2+)-dependent interconversion of the enantiomers of mandelate. Several α-keto acids are modest competitive inhibitors of MR [e.g., mesoxalate (Ki = 1.8 ± 0.3 mM) and 3-fluoropyruvate (Ki = 1.3 ± 0.1 mM)], but, surprisingly, 3-hydroxypyruvate (3-HP) is an irreversible, time-dependent inhibitor (kinact/KI = 83 ± 8 M(-1) s(-1)). Protection from inactivation by the competitive inhibitor benzohydroxamate, trypsinolysis and electrospray ionization tandem mass spectrometry analyses, and X-ray crystallographic studies reveal that 3-HP undergoes Schiff-base formation with Lys 166 at the active site, followed by formation of an aldehyde/enol(ate) adduct. Such a reaction is unprecedented in the enolase superfamily and may be a relic of an activity possessed by a promiscuous progenitor enzyme. The ability of MR to form and deprotonate a Schiff-base intermediate furnishes a previously unrecognized mechanistic link to other α/β-barrel enzymes utilizing Schiff-base chemistry and is in accord with the sequence- and structure-based hypothesis that members of the metal-dependent enolase superfamily and the Schiff-base-forming N-acetylneuraminate lyase superfamily and aldolases share a common ancestor.
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Affiliation(s)
- Mitesh Nagar
- †Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Brittney N Wyatt
- ‡Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin 53201-1881, United States
| | - Martin St Maurice
- ‡Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin 53201-1881, United States
| | - Stephen L Bearne
- †Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada.,§Department of Chemistry, Dalhousie University, Halifax, NS B3H 4R2, Canada
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Lewin R, Goodall M, Thompson ML, Leigh J, Breuer M, Baldenius K, Micklefield J. Enzymatic enantioselective decarboxylative protonation of heteroaryl malonates. Chemistry 2015; 21:6557-63. [PMID: 25766433 PMCID: PMC4517146 DOI: 10.1002/chem.201406014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Indexed: 12/28/2022]
Abstract
The enzyme aryl/alkenyl malonate decarboxylase (AMDase) catalyses the enantioselective decarboxylative protonation (EDP) of a range of disubstituted malonic acids to give homochiral carboxylic acids that are valuable synthetic intermediates. AMDase exhibits a number of advantages over the non-enzymatic EDP methods developed to date including higher enantioselectivity and more environmentally benign reaction conditions. In this report, AMDase and engineered variants have been used to produce a range of enantioenriched heteroaromatic α-hydroxycarboxylic acids, including pharmaceutical precursors, from readily accessible α-hydroxymalonates. The enzymatic method described here represents an improvement upon existing synthetic chemistry methods that have been used to produce similar compounds. The relationship between the structural features of these new substrates and the kinetics associated with their enzymatic decarboxylation is explored, which offers further insight into the mechanism of AMDase.
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Affiliation(s)
- Ross Lewin
- School of Chemistry and Manchester Institute of Biotechnology, The University of Manchester131 Princess Street, Manchester M1 7ND (UK) E-mail:
| | - Mark Goodall
- School of Chemistry and Manchester Institute of Biotechnology, The University of Manchester131 Princess Street, Manchester M1 7ND (UK) E-mail:
| | - Mark L Thompson
- School of Chemistry and Manchester Institute of Biotechnology, The University of Manchester131 Princess Street, Manchester M1 7ND (UK) E-mail:
| | - James Leigh
- School of Chemistry and Manchester Institute of Biotechnology, The University of Manchester131 Princess Street, Manchester M1 7ND (UK) E-mail:
| | | | | | - Jason Micklefield
- School of Chemistry and Manchester Institute of Biotechnology, The University of Manchester131 Princess Street, Manchester M1 7ND (UK) E-mail:
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Prediction of substrate specificity and preliminary kinetic characterization of the hypothetical protein PVX_123945 from Plasmodium vivax. Exp Parasitol 2015; 151-152:56-63. [PMID: 25655405 DOI: 10.1016/j.exppara.2015.01.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2014] [Revised: 01/12/2015] [Accepted: 01/27/2015] [Indexed: 11/22/2022]
Abstract
Members of the haloacid dehalogenase (HAD) superfamily are emerging as an important group of enzymes by virtue of their role in diverse chemical reactions. In different Plasmodium species their number varies from 16 to 21. One of the HAD superfamily members, PVX_123945, a hypothetical protein from Plasmodium vivax, was selected for examining its substrate specificity. Based on distant homology searches and structure comparisons, it was predicted to be a phosphatase. Thirty-eight metabolites were screened to identify potential substrates. Further, to validate the prediction, biochemical and kinetic studies were carried out that showed that the protein was a monomer with high catalytic efficiency for β-glycerophosphate followed by pyridoxal 5'-phosphate. The enzyme also exhibited moderate catalytic efficiencies for α-glycerophosphate, xanthosine 5'-monophosphate and adenosine 5'-monophosphate. It also hydrolyzed the artificial substrate p-nitrophenyl phosphate (pNPP). Mg(2+) was the most preferred divalent cation and phosphate inhibited the enzyme activity. The study is the first attempt at understanding the substrate specificity of a hypothetical protein belonging to HAD superfamily from the malarial parasite P. vivax.
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