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Aro N, Ercili-Cura D, Andberg M, Silventoinen P, Lille M, Hosia W, Nordlund E, Landowski CP. Production of bovine beta-lactoglobulin and hen egg ovalbumin by Trichoderma reesei using precision fermentation technology and testing of their techno-functional properties. Food Res Int 2023; 163:112131. [PMID: 36596092 DOI: 10.1016/j.foodres.2022.112131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 10/17/2022] [Accepted: 11/13/2022] [Indexed: 11/18/2022]
Abstract
The food protein ingredient market is dominated by dairy and egg proteins. Both milk whey and egg proteins are challenging proteins to replace, e.g. with plant proteins, due to the unique structural features of the animal proteins that render them highly functional. Thus, to provide a non-animal source of these important proteins the fungal host Trichoderma reesei was utilized for the biotechnical production of recombinant hen ovalbumin (TrOVA) and bovine beta lactoglobulin (TrBLG). These food proteins were investigated using two different promoter systems to test the concept of effectively expressing them in a fungal host. Both proteins were successfully produced in 24 well plate and bioreactor scale. The production level of TrBLG and TrOVA were 1 g/L and 2 g/L, respectively. Both proteins were further purified and characterized, and their functional properties were tested. TrBLG and TrOVA secondary structures determined by circular dichroism corresponded to the proteins of bovine and hen. The T. reesei produced proteins were found to be N-glycosylated, mostly with Man 5. TrBLG had emulsification properties matching to corresponding bovine protein. TrOVA showed excellent foaming characteristics and heat-induced gelation, although the strength of the gel was somewhat lower than with hen ovalbumin, possibly due to the partial degradation of TrOVA or presence of other host proteins. Biotechnical production of whey and egg proteins using precision fermentation technology offers an innovative way to increase the sustainability of the conventional food industry, without further reliance on animal farming. Industrial relevance: The food protein ingredient market is dominated by dairy (largely whey proteins) and egg proteins. Whey proteins are valuable and versatile food ingredients due to their functional and nutritional quality. They are largely used in meat and milk products, low fat products, bakery, confectionary, infant formulas and sports nutrition. Similarly, egg white protein ovalbumin is a highly functional protein ingredient that facilitates structure formation and high nutritional quality in most food products. Together they comprise 40-70% of the revenue in the animal protein ingredients market. Both whey and egg proteins are extremely challenging proteins to replace, e.g., by plant proteins due to their unique structural features that render them with high functionality. Biotechnical production of whey and egg proteins using precision fermentation technology offers an innovative way to increase the sustainability of the conventional food industry, without further reliance on animal farming.
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Affiliation(s)
- Nina Aro
- VTT Technical Research Centre of Finland Ltd, P.O. Box 1000, FI-02044 VTT, Espoo, Finland.
| | - Dilek Ercili-Cura
- VTT Technical Research Centre of Finland Ltd, P.O. Box 1000, FI-02044 VTT, Espoo, Finland
| | - Martina Andberg
- VTT Technical Research Centre of Finland Ltd, P.O. Box 1000, FI-02044 VTT, Espoo, Finland
| | - Pia Silventoinen
- VTT Technical Research Centre of Finland Ltd, P.O. Box 1000, FI-02044 VTT, Espoo, Finland
| | - Martina Lille
- VTT Technical Research Centre of Finland Ltd, P.O. Box 1000, FI-02044 VTT, Espoo, Finland
| | - Waltteri Hosia
- VTT Technical Research Centre of Finland Ltd, P.O. Box 1000, FI-02044 VTT, Espoo, Finland
| | - Emilia Nordlund
- VTT Technical Research Centre of Finland Ltd, P.O. Box 1000, FI-02044 VTT, Espoo, Finland
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Pääkkönen J, Hakulinen N, Andberg M, Koivula A, Rouvinen J. Three-dimensional structure of xylonolactonase from Caulobacter crescentus: A mononuclear iron enzyme of the 6-bladed β-propeller hydrolase family. Protein Sci 2021; 31:371-383. [PMID: 34761460 PMCID: PMC8820113 DOI: 10.1002/pro.4229] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 11/02/2021] [Accepted: 11/02/2021] [Indexed: 11/22/2022]
Abstract
Xylonolactonase Cc XylC from Caulobacter crescentus catalyzes the hydrolysis of the intramolecular ester bond of d‐xylonolactone. We have determined crystal structures of Cc XylC in complex with d‐xylonolactone isomer analogues d‐xylopyranose and (r)‐(+)‐4‐hydroxy‐2‐pyrrolidinone at high resolution. Cc XylC has a 6‐bladed β‐propeller architecture, which contains a central open channel having the active site at one end. According to our previous native mass spectrometry studies, Cc XylC is able to specifically bind Fe2+. The crystal structures, presented here, revealed an active site bound metal ion with an octahedral binding geometry. The side chains of three amino acid residues, Glu18, Asn146, and Asp196, which participate in binding of metal ion are located in the same plane. The solved complex structures allowed suggesting a reaction mechanism for intramolecular ester bond hydrolysis in which the major contribution for catalysis arises from the carbonyl oxygen coordination of the xylonolactone substrate to the Fe2+. The structure of Cc XylC was compared with eight other ester hydrolases of the β‐propeller hydrolase family. The previously published crystal structures of other β‐propeller hydrolases contain either Ca2+, Mg2+, or Zn2+ and show clear similarities in ligand and metal ion binding geometries to that of Cc XylC. It would be interesting to reinvestigate the metal binding specificity of these enzymes and clarify whether they are also able to use Fe2+ as a catalytic metal. This could further expand our understanding of utilization of Fe2+ not only in oxidative enzymes but also in hydrolases. PDB Code(s): 7PLB, 7PLC and 7PLD;
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Affiliation(s)
- Johan Pääkkönen
- Department of Chemistry, University of Eastern Finland, Joensuu, Finland
| | - Nina Hakulinen
- Department of Chemistry, University of Eastern Finland, Joensuu, Finland
| | - Martina Andberg
- VTT Technical Research Centre of Finland Ltd, Espoo, Finland
| | - Anu Koivula
- VTT Technical Research Centre of Finland Ltd, Espoo, Finland
| | - Juha Rouvinen
- Department of Chemistry, University of Eastern Finland, Joensuu, Finland
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Pääkkönen J, Penttinen L, Andberg M, Koivula A, Hakulinen N, Rouvinen J, Jänis J. Xylonolactonase from Caulobacter crescentus Is a Mononuclear Nonheme Iron Hydrolase. Biochemistry 2021; 60:3046-3049. [PMID: 34633186 PMCID: PMC8529709 DOI: 10.1021/acs.biochem.1c00249] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Caulobacter crescentus xylonolactonase (Cc XylC, EC 3.1.1.68) catalyzes an intramolecular ester bond hydrolysis over a nonenzymatic acid/base catalysis. Cc XylC is a member of the SMP30 protein family, whose members have previously been reported to be active in the presence of bivalent metal ions, such as Ca2+, Zn2+, and Mg2+. By native mass spectrometry, we studied the binding of several bivalent metal ions to Cc XylC and observed that it binds only one of them, namely, the Fe2+ cation, specifically and with a high affinity (Kd = 0.5 μM), pointing out that Cc XylC is a mononuclear iron protein. We propose that bivalent metal cations also promote the reaction nonenzymatically by stabilizing a short-lived bicyclic intermediate on the lactone isomerization reaction. An analysis of the reaction kinetics showed that Cc XylC complexed with Fe2+ can speed up the hydrolysis of d-xylono-1,4-lactone by 100-fold and that of d-glucono-1,5-lactone by 10-fold as compared to the nonenzymatic reaction. To our knowledge, this is the first discovery of a nonheme mononuclear iron-binding enzyme that catalyzes an ester bond hydrolysis reaction.
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Affiliation(s)
- Johan Pääkkönen
- Department of Chemistry, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland
| | - Leena Penttinen
- Department of Chemistry, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland
| | - Martina Andberg
- VTT Technical Research Centre of Finland Ltd, P.O. Box 1000, FI-02044 VTT Espoo, Finland
| | - Anu Koivula
- VTT Technical Research Centre of Finland Ltd, P.O. Box 1000, FI-02044 VTT Espoo, Finland
| | - Nina Hakulinen
- Department of Chemistry, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland
| | - Juha Rouvinen
- Department of Chemistry, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland
| | - Janne Jänis
- Department of Chemistry, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland
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Voutilainen S, Heinonen M, Andberg M, Jokinen E, Maaheimo H, Pääkkönen J, Hakulinen N, Rouvinen J, Lähdesmäki H, Kaski S, Rousu J, Penttilä M, Koivula A. Substrate specificity of 2-deoxy-D-ribose 5-phosphate aldolase (DERA) assessed by different protein engineering and machine learning methods. Appl Microbiol Biotechnol 2020; 104:10515-10529. [PMID: 33147349 PMCID: PMC7671976 DOI: 10.1007/s00253-020-10960-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 10/01/2020] [Accepted: 10/12/2020] [Indexed: 11/29/2022]
Abstract
In this work, deoxyribose-5-phosphate aldolase (Ec DERA, EC 4.1.2.4) from Escherichia coli was chosen as the protein engineering target for improving the substrate preference towards smaller, non-phosphorylated aldehyde donor substrates, in particular towards acetaldehyde. The initial broad set of mutations was directed to 24 amino acid positions in the active site or in the close vicinity, based on the 3D complex structure of the E. coli DERA wild-type aldolase. The specific activity of the DERA variants containing one to three amino acid mutations was characterised using three different substrates. A novel machine learning (ML) model utilising Gaussian processes and feature learning was applied for the 3rd mutagenesis round to predict new beneficial mutant combinations. This led to the most clear-cut (two- to threefold) improvement in acetaldehyde (C2) addition capability with the concomitant abolishment of the activity towards the natural donor molecule glyceraldehyde-3-phosphate (C3P) as well as the non-phosphorylated equivalent (C3). The Ec DERA variants were also tested on aldol reaction utilising formaldehyde (C1) as the donor. Ec DERA wild-type was shown to be able to carry out this reaction, and furthermore, some of the improved variants on acetaldehyde addition reaction turned out to have also improved activity on formaldehyde. KEY POINTS: • DERA aldolases are promiscuous enzymes. • Synthetic utility of DERA aldolase was improved by protein engineering approaches. • Machine learning methods aid the protein engineering of DERA.
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Affiliation(s)
- Sanni Voutilainen
- VTT Technical Research Centre of Finland Ltd, P.O. Box 1000, FI-02044 VTT, Espoo, Finland.
| | - Markus Heinonen
- Department of Computer Science, Aalto University, Espoo, Finland
- Helsinki Institute for Information Technology, Espoo, Finland
| | - Martina Andberg
- VTT Technical Research Centre of Finland Ltd, P.O. Box 1000, FI-02044 VTT, Espoo, Finland
| | - Emmi Jokinen
- Department of Computer Science, Aalto University, Espoo, Finland
| | - Hannu Maaheimo
- VTT Technical Research Centre of Finland Ltd, P.O. Box 1000, FI-02044 VTT, Espoo, Finland
| | - Johan Pääkkönen
- Department of Chemistry, University of Eastern Finland, PO Box 111, FI-80101, Joensuu, Finland
| | - Nina Hakulinen
- Department of Chemistry, University of Eastern Finland, PO Box 111, FI-80101, Joensuu, Finland
| | - Juha Rouvinen
- Department of Chemistry, University of Eastern Finland, PO Box 111, FI-80101, Joensuu, Finland
| | - Harri Lähdesmäki
- Department of Computer Science, Aalto University, Espoo, Finland
| | - Samuel Kaski
- Department of Computer Science, Aalto University, Espoo, Finland
- Helsinki Institute for Information Technology, Espoo, Finland
| | - Juho Rousu
- Department of Computer Science, Aalto University, Espoo, Finland
- Helsinki Institute for Information Technology, Espoo, Finland
| | - Merja Penttilä
- VTT Technical Research Centre of Finland Ltd, P.O. Box 1000, FI-02044 VTT, Espoo, Finland
| | - Anu Koivula
- VTT Technical Research Centre of Finland Ltd, P.O. Box 1000, FI-02044 VTT, Espoo, Finland
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Vartiainen E, Blomberg P, Ilmén M, Andberg M, Toivari M, Penttilä M. Evaluation of synthetic formaldehyde and methanol assimilation pathways in Yarrowia lipolytica. Fungal Biol Biotechnol 2019; 6:27. [PMID: 31890234 PMCID: PMC6918578 DOI: 10.1186/s40694-019-0090-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 12/03/2019] [Indexed: 11/10/2022] Open
Abstract
Background Crude glycerol coming from biodiesel production is an attractive carbon source for biological production of chemicals. The major impurity in preparations of crude glycerol is methanol, which is toxic for most microbes. Development of microbes, which would not only tolerate the methanol, but also use it as co-substrate, would increase the feasibility of bioprocesses using crude glycerol as substrate. Results To prevent methanol conversion to CO2 via formaldehyde and formate, the formaldehyde dehydrogenase (FLD) gene was identified in and deleted from Yarrowia lipolytica. The deletion strain was able to convert methanol to formaldehyde without expression of heterologous methanol dehydrogenases. Further, it was shown that expression of heterologous formaldehyde assimilating enzymes could complement the deletion of FLD. The expression of either 3-hexulose-6-phosphate synthase (HPS) enzyme of ribulose monosphosphate pathway or dihydroxyacetone synthase (DHAS) enzyme of xylulose monosphosphate pathway restored the formaldehyde tolerance of the formaldehyde sensitive Δfld1 strain. Conclusions In silico, the expression of heterologous formaldehyde assimilation pathways enable Y. lipolytica to use methanol as substrate for growth and metabolite production. In vivo, methanol was shown to be converted to formaldehyde and the enzymes of formaldehyde assimilation were actively expressed in this yeast. However, further development is required to enable Y. lipolytica to efficiently use methanol as co-substrate with glycerol.
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Affiliation(s)
- Eija Vartiainen
- VTT Technical Research Centre of Finland Ltd, P.O. Box 1000, 02044 VTT Espoo, Finland
| | - Peter Blomberg
- VTT Technical Research Centre of Finland Ltd, P.O. Box 1000, 02044 VTT Espoo, Finland
| | - Marja Ilmén
- VTT Technical Research Centre of Finland Ltd, P.O. Box 1000, 02044 VTT Espoo, Finland
| | - Martina Andberg
- VTT Technical Research Centre of Finland Ltd, P.O. Box 1000, 02044 VTT Espoo, Finland
| | - Mervi Toivari
- VTT Technical Research Centre of Finland Ltd, P.O. Box 1000, 02044 VTT Espoo, Finland
| | - Merja Penttilä
- VTT Technical Research Centre of Finland Ltd, P.O. Box 1000, 02044 VTT Espoo, Finland
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Thangaraj S, Voutilainen S, Andberg M, Koivula A, Jänis J, Rouvinen J. Bioconjugation with Aminoalkylhydrazine for Efficient Mass Spectrometry-Based Detection of Small Carbonyl Compounds. ACS Omega 2019; 4:13447-13453. [PMID: 31460473 PMCID: PMC6705233 DOI: 10.1021/acsomega.9b01691] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2019] [Accepted: 07/25/2019] [Indexed: 05/24/2023]
Abstract
Bioconjugation through oxime or hydrazone formation is a versatile strategy for covalent labeling of biomolecules in vitro and in vivo. In this work, a mass spectrometry-based method was developed for the bioconjugation of small carbonyl compounds (CCs) with an aminoalkylhydrazine to form stable hydrazone conjugates that are readily detectable with electrospray ionization mass spectrometry (ESI-MS). Out of all hydrazine reagents tested, 2-(dimethylamino)ethylhydrazine (DMAEH) was selected for further analysis due to the fastest reaction rates observed. A thorough study of the reaction kinetics between structurally varied short-chain CCs and DMAEH was performed with the second-order reaction rate constants spanning in the range of 0.23-208 M-1 s-1. In general, small aldehydes reacted faster than the corresponding ketones. Moreover, a successful reaction monitoring of a deoxyribose-5-phosphate aldolase-catalyzed reversible retro-aldol cleavage of deoxyribose was demonstrated. Thus, the developed method shows potential also for ESI-MS-based enzyme kinetics studies.
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Affiliation(s)
- Senthil
K. Thangaraj
- Department
of Chemistry, University of Eastern Finland, PO Box 111, FI-80101 Joensuu, Finland
| | - Sanni Voutilainen
- VTT
Technical Research Centre of Finland Ltd, PO Box 1000, FI-020444 VTT, Espoo, Finland
| | - Martina Andberg
- VTT
Technical Research Centre of Finland Ltd, PO Box 1000, FI-020444 VTT, Espoo, Finland
| | - Anu Koivula
- VTT
Technical Research Centre of Finland Ltd, PO Box 1000, FI-020444 VTT, Espoo, Finland
| | - Janne Jänis
- Department
of Chemistry, University of Eastern Finland, PO Box 111, FI-80101 Joensuu, Finland
| | - Juha Rouvinen
- Department
of Chemistry, University of Eastern Finland, PO Box 111, FI-80101 Joensuu, Finland
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Boer H, Andberg M, Pylkkänen R, Maaheimo H, Koivula A. In vitro reconstitution and characterisation of the oxidative D-xylose pathway for production of organic acids and alcohols. AMB Express 2019; 9:48. [PMID: 30972503 PMCID: PMC6458216 DOI: 10.1186/s13568-019-0768-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 03/25/2019] [Indexed: 01/01/2023] Open
Abstract
The oxidative d-xylose pathway, i.e. Dahms pathway, can be utilised to produce from cheap biomass raw material useful chemical intermediates. In vitro metabolic pathways offer a fast way to study the rate-limiting steps and find the most suitable enzymes for each reaction. We have constructed here in vitro multi-enzyme cascades leading from d-xylose or d-xylonolactone to ethylene glycol, glycolic acid and lactic acid, and use simple spectrophotometric assays for the read-out of the efficiency of these pathways. Based on our earlier results, we focussed particularly on the less studied xylonolactone ring opening (hydrolysis) reaction. The bacterial Caulobacter crescentus lactonase (Cc XylC), was shown to be a metal-dependent enzyme clearly improving the formation of d-xylonic acid at pH range from 6 to 8. The following dehydration reaction by the ILVD/EDD family d-xylonate dehydratase is a rate-limiting step in the pathway, and an effort was made to screen for novel enolase family d-xylonate dehydratases, however, no suitable replacing enzymes were found for this reaction. Concerning the oxidation of glycolaldehyde to glycolic acid, several enzyme candidates were also tested. Both Escherichia coli aldehyde dehydrogenase (Ec AldA) and Azospirillum brasilense α-ketoglutarate semialdehyde dehydrogenase (Ab AraE) proved to be suitable enzymes for this reaction.
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Rahman MM, Andberg M, Koivula A, Rouvinen J, Hakulinen N. The crystal structure of D-xylonate dehydratase reveals functional features of enzymes from the Ilv/ED dehydratase family. Sci Rep 2018; 8:865. [PMID: 29339766 PMCID: PMC5770437 DOI: 10.1038/s41598-018-19192-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 12/22/2017] [Indexed: 01/06/2023] Open
Abstract
The Ilv/ED dehydratase protein family includes dihydroxy acid-, gluconate-, 6-phosphogluconate- and pentonate dehydratases. The members of this family are involved in various biosynthetic and carbohydrate metabolic pathways. Here, we describe the first crystal structure of D-xylonate dehydratase from Caulobacter crescentus (CcXyDHT) at 2.7 Å resolution and compare it with other available enzyme structures from the IlvD/EDD protein family. The quaternary structure of CcXyDHT is a tetramer, and each monomer is composed of two domains in which the N-terminal domain forms a binding site for a [2Fe-2S] cluster and a Mg2+ ion. The active site is located at the monomer-monomer interface and contains residues from both the N-terminal recognition helix and the C-terminus of the dimeric counterpart. The active site also contains a conserved Ser490, which probably acts as a base in catalysis. Importantly, the cysteines that participate in the binding and formation of the [2Fe-2S] cluster are not all conserved within the Ilv/ED dehydratase family, which suggests that some members of the IlvD/EDD family may bind different types of [Fe-S] clusters.
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Affiliation(s)
- Mohammad Mubinur Rahman
- Department of Chemistry, University of Eastern Finland, PO Box 111, FIN-80101, Joensuu, Finland
| | - Martina Andberg
- VTT Technical Research Centre of Finland Ltd, PO Box 1000, FIN-02044 VTT, Espoo, Finland
| | - Anu Koivula
- VTT Technical Research Centre of Finland Ltd, PO Box 1000, FIN-02044 VTT, Espoo, Finland
| | - Juha Rouvinen
- Department of Chemistry, University of Eastern Finland, PO Box 111, FIN-80101, Joensuu, Finland
| | - Nina Hakulinen
- Department of Chemistry, University of Eastern Finland, PO Box 111, FIN-80101, Joensuu, Finland.
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Rahman MM, Andberg M, Thangaraj SK, Parkkinen T, Penttilä M, Jänis J, Koivula A, Rouvinen J, Hakulinen N. The Crystal Structure of a Bacterial l-Arabinonate Dehydratase Contains a [2Fe-2S] Cluster. ACS Chem Biol 2017; 12:1919-1927. [PMID: 28574691 DOI: 10.1021/acschembio.7b00304] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We present a novel crystal structure of the IlvD/EDD family enzyme, l-arabinonate dehydratase from Rhizobium leguminosarum bv. trifolii (RlArDHT, EC 4.2.1.25), which catalyzes the conversion of l-arabinonate to 2-dehydro-3-deoxy-l-arabinonate. The enzyme is a tetramer consisting of a dimer of dimers, where each monomer is composed of two domains. The active site contains a catalytically important [2Fe-2S] cluster and Mg2+ ion and is buried between two domains, and also at the dimer interface. The active site Lys129 was found to be carbamylated. Ser480 and Thr482 were shown to be essential residues for catalysis, and the S480A mutant structure showed an unexpected open conformation in which the active site was more accessible for the substrate. This structure showed the partial binding of l-arabinonate, which allowed us to suggest that the alkoxide ion form of the Ser480 side chain functions as a base and the [2Fe-2S] cluster functions as a Lewis acid in the elimination reaction.
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Affiliation(s)
- Mohammad Mubinur Rahman
- Department
of Chemistry, University of Eastern Finland, P.O. Box 111, FIN-80101 Joensuu, Finland
| | - Martina Andberg
- VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, FIN-02044 VTT, Espoo, Finland
| | - Senthil Kumar Thangaraj
- Department
of Chemistry, University of Eastern Finland, P.O. Box 111, FIN-80101 Joensuu, Finland
| | - Tarja Parkkinen
- Department
of Chemistry, University of Eastern Finland, P.O. Box 111, FIN-80101 Joensuu, Finland
| | - Merja Penttilä
- VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, FIN-02044 VTT, Espoo, Finland
| | - Janne Jänis
- Department
of Chemistry, University of Eastern Finland, P.O. Box 111, FIN-80101 Joensuu, Finland
| | - Anu Koivula
- VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, FIN-02044 VTT, Espoo, Finland
| | - Juha Rouvinen
- Department
of Chemistry, University of Eastern Finland, P.O. Box 111, FIN-80101 Joensuu, Finland
| | - Nina Hakulinen
- Department
of Chemistry, University of Eastern Finland, P.O. Box 111, FIN-80101 Joensuu, Finland
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Rahman MM, Andberg M, Koivula A, Rouvinen J, Hakulinen N. Crystallization and X-ray diffraction analysis of an L-arabinonate dehydratase from Rhizobium leguminosarum bv. trifolii and a D-xylonate dehydratase from Caulobacter crescentus. Acta Crystallogr F Struct Biol Commun 2016; 72:604-8. [PMID: 27487924 PMCID: PMC4973301 DOI: 10.1107/s2053230x16010311] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 06/25/2016] [Indexed: 11/28/2022]
Abstract
l-Arabinonate dehydratase and d-xylonate dehydratase from the IlvD/EDD family were crystallized by the vapour-diffusion method. Diffraction data sets were collected to resolutions of 2.40 and 2.66 Å from crystals of l-arabinonate dehydratase and d-xylonate dehydratase, respectively. l-Arabinonate dehydratase (EC 4.2.1.25) and d-xylonate dehydratase (EC 4.2.1.82) are two enzymes that are involved in a nonphosphorylative oxidation pathway of pentose sugars. l-Arabinonate dehydratase converts l-arabinonate into 2-dehydro-3-deoxy-l-arabinonate, and d-xylonate dehydratase catalyzes the dehydration of d-xylonate to 2-dehydro-3-deoxy-d-xylonate. l-Arabinonate and d-xylonate dehydratases belong to the IlvD/EDD family, together with 6-phosphogluconate dehydratases and dihydroxyacid dehydratases. No crystal structure of any l-arabinonate or d-xylonate dehydratase is available in the PDB. In this study, recombinant l-arabinonate dehydratase from Rhizobium leguminosarum bv. trifolii (RlArDHT) and d-xylonate dehydratase from Caulobacter crescentus (CcXyDHT) were heterologously expressed in Escherichia coli and purified by the use of affinity chromatography followed by gel-filtration chromatography. The purified proteins were crystallized using the hanging-drop vapour-diffusion method at 293 K. Crystals of RlArDHT that diffracted to 2.40 Å resolution were obtained using sodium formate as a precipitating agent. They belonged to space group P21, with unit-cell parameters a = 106.07, b = 208.61, c = 147.09 Å, β = 90.43°. Eight RlArDHT molecules (two tetramers) in the asymmetric unit give a VM value of 3.2 Å3 Da−1 and a solvent content of 62%. Crystals of CcXyDHT that diffracted to 2.66 Å resolution were obtained using sodium formate and polyethylene glycol 3350. They belonged to space group C2, with unit-cell parameters a = 270.42, b = 236.13, c = 65.17 Å, β = 97.38°. Four CcXyDHT molecules (a tetramer) in the asymmetric unit give a VM value of 4.0 Å3 Da−1 and a solvent content of 69%.
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Affiliation(s)
- Mohammad Mubinur Rahman
- Department of Chemistry, University of Eastern Finland, Joensuu Campus, PO Box 111, FIN-80101 Joensuu, Finland
| | - Martina Andberg
- VTT Technical Research Centre of Finland Ltd, PO Box 1000, FIN-02044 VTT Espoo, Finland
| | - Anu Koivula
- VTT Technical Research Centre of Finland Ltd, PO Box 1000, FIN-02044 VTT Espoo, Finland
| | - Juha Rouvinen
- Department of Chemistry, University of Eastern Finland, Joensuu Campus, PO Box 111, FIN-80101 Joensuu, Finland
| | - Nina Hakulinen
- Department of Chemistry, University of Eastern Finland, Joensuu Campus, PO Box 111, FIN-80101 Joensuu, Finland
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11
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Andberg M, Aro-Kärkkäinen N, Carlson P, Oja M, Bozonnet S, Toivari M, Hakulinen N, O'Donohue M, Penttilä M, Koivula A. Characterization and mutagenesis of two novel iron-sulphur cluster pentonate dehydratases. Appl Microbiol Biotechnol 2016; 100:7549-63. [PMID: 27102126 DOI: 10.1007/s00253-016-7530-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 03/15/2016] [Accepted: 03/29/2016] [Indexed: 10/21/2022]
Abstract
We describe here the identification and characterization of two novel enzymes belonging to the IlvD/EDD protein family, the D-xylonate dehydratase from Caulobacter crescentus, Cc XyDHT, (EC 4.2.1.82), and the L-arabonate dehydratase from Rhizobium leguminosarum bv. trifolii, Rl ArDHT (EC 4.2.1.25), that produce the corresponding 2-keto-3-deoxy-sugar acids. There is only a very limited amount of characterization data available on pentonate dehydratases, even though the enzymes from these oxidative pathways have potential applications with plant biomass pentose sugars. The two bacterial enzymes share 41 % amino acid sequence identity and were expressed and purified from Escherichia coli as homotetrameric proteins. Both dehydratases were shown to accept pentonate and hexonate sugar acids as their substrates and require Mg(2+) for their activity. Cc XyDHT displayed the highest activity on D-xylonate and D-gluconate, while Rl ArDHT functioned best on D-fuconate, L-arabonate and D-galactonate. The configuration of the OH groups at C2 and C3 position of the sugar acid were shown to be critical, and the C4 configuration also contributed substantially to the substrate recognition. The two enzymes were also shown to contain an iron-sulphur [Fe-S] cluster. Our phylogenetic analysis and mutagenesis studies demonstrated that the three conserved cysteine residues in the aldonic acid dehydratase group of IlvD/EDD family members, those of C60, C128 and C201 in Cc XyDHT, and of C59, C127 and C200 in Rl ArDHT, are needed for coordination of the [Fe-S] cluster. The iron-sulphur cluster was shown to be crucial for the catalytic activity (kcat) but not for the substrate binding (Km) of the two pentonate dehydratases.
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Affiliation(s)
- Martina Andberg
- VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, VTT, FI-02044, Espoo, Finland.
| | - Niina Aro-Kärkkäinen
- VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, VTT, FI-02044, Espoo, Finland
| | - Paul Carlson
- VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, VTT, FI-02044, Espoo, Finland
| | - Merja Oja
- VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, VTT, FI-02044, Espoo, Finland
| | - Sophie Bozonnet
- INSA, UPS, INP; LISBP, Université de Toulouse, 135 Avenue de Rangueil, F-31077, Toulouse, France.,INRA, UMR792, Ingénierie des Systèmes Biologiques et des Procédés, F-31400, Toulouse, France.,CNRS, UMR5504, F-31400, Toulouse, France
| | - Mervi Toivari
- VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, VTT, FI-02044, Espoo, Finland
| | - Nina Hakulinen
- Department of Chemistry, University of Eastern Finland, PO Box 111, FI-80101, Joensuu, Finland
| | - Michael O'Donohue
- INSA, UPS, INP; LISBP, Université de Toulouse, 135 Avenue de Rangueil, F-31077, Toulouse, France.,INRA, UMR792, Ingénierie des Systèmes Biologiques et des Procédés, F-31400, Toulouse, France.,CNRS, UMR5504, F-31400, Toulouse, France
| | - Merja Penttilä
- VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, VTT, FI-02044, Espoo, Finland
| | - Anu Koivula
- VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, VTT, FI-02044, Espoo, Finland
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12
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Taberman H, Andberg M, Koivula A, Rouvinen J, Parkkinen T. Crystal structure of a novel Caulobacter crescentusoxidoreductase and its complexes. Acta Crystallogr A Found Adv 2015. [DOI: 10.1107/s2053273315096795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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13
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Andberg M, Penttilä M, Saloheimo M. Swollenin from Trichoderma reesei exhibits hydrolytic activity against cellulosic substrates with features of both endoglucanases and cellobiohydrolases. Bioresour Technol 2015; 181:105-13. [PMID: 25643956 DOI: 10.1016/j.biortech.2015.01.024] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2014] [Revised: 01/07/2015] [Accepted: 01/08/2015] [Indexed: 05/21/2023]
Abstract
The cellulolytic and hemicellulolytic enzymes of Trichoderma reesei comprise one of the best characterised enzyme systems involved in lignocellulose degradation. In this paper, swollenin (SWOI), a protein recognised based on its sequence similarity with plant expansins, has been characterised. SWOI and its catalytic domain were subjected to analysis of their hydrolytic activity on different soluble carbohydrate polymers. By measuring the production of reducing ends, zymogram-, and viscosity analysis, SWOI was shown to have activity on substrates containing β-1,4 glucosidic bonds, i.e. carboxymethyl cellulose, hydroxyethyl cellulose and β-glucan. The formation of oligosaccharides from β-glucan was analysed by HPLC and showed cellobiose as the main reaction product. SWOI was also able to hydrolyse soluble cello-oligosaccharides and the products formed were all consistent with SWOI cleaving a cellobiose unit off the substrate. In conclusion, the T. reesei swollenin showed a unique mode of action with similarities with action of both endoglucanases and cellobiohydrolases.
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Affiliation(s)
- Martina Andberg
- VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT Espoo, Finland.
| | - Merja Penttilä
- VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT Espoo, Finland
| | - Markku Saloheimo
- VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT Espoo, Finland
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14
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Taberman H, Andberg M, Parkkinen T, Jänis J, Penttilä M, Hakulinen N, Koivula A, Rouvinen J. Structure and function of a decarboxylating Agrobacterium tumefaciens keto-deoxy-d-galactarate dehydratase. Biochemistry 2014; 53:8052-60. [PMID: 25454257 DOI: 10.1021/bi501290k] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Agrobacterium tumefaciens (At) strain C58 contains an oxidative enzyme pathway that can function on both d-glucuronic and d-galacturonic acid. The corresponding gene coding for At keto-deoxy-d-galactarate (KDG) dehydratase is located in the same gene cluster as those coding for uronate dehydrogenase (At Udh) and galactarolactone cycloisomerase (At Gci) which we have previously characterized. Here, we present the kinetic characterization and crystal structure of At KDG dehydratase, which catalyzes the next step, the decarboxylating hydrolyase reaction of KDG to produce α-ketoglutaric semialdehyde (α-KGSA) and carbon dioxide. The crystal structures of At KDG dehydratase and its complexes with pyruvate and 2-oxoadipic acid, two substrate analogues, were determined to 1.7 Å, 1.5 Å, and 2.1 Å resolution, respectively. Furthermore, mass spectrometry was used to confirm reaction end-products. The results lead us to propose a structure-based mechanism for At KDG dehydratase, suggesting that while the enzyme belongs to the Class I aldolase protein family, it does not follow a typical retro-aldol condensation mechanism.
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Affiliation(s)
- Helena Taberman
- Department of Chemistry, University of Eastern Finland , FI-80101 Joensuu, Finland
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15
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Aro-Kärkkäinen N, Toivari M, Maaheimo H, Ylilauri M, Pentikäinen OT, Andberg M, Oja M, Penttilä M, Wiebe MG, Ruohonen L, Koivula A. L-arabinose/D-galactose 1-dehydrogenase of Rhizobium leguminosarum bv. trifolii characterised and applied for bioconversion of L-arabinose to L-arabonate with Saccharomyces cerevisiae. Appl Microbiol Biotechnol 2014; 98:9653-65. [PMID: 25236800 DOI: 10.1007/s00253-014-6039-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 08/13/2014] [Accepted: 08/18/2014] [Indexed: 10/24/2022]
Abstract
Four potential dehydrogenases identified through literature and bioinformatic searches were tested for L-arabonate production from L-arabinose in the yeast Saccharomyces cerevisiae. The most efficient enzyme, annotated as a D-galactose 1-dehydrogenase from the pea root nodule bacterium Rhizobium leguminosarum bv. trifolii, was purified from S. cerevisiae as a homodimeric protein and characterised. We named the enzyme as a L-arabinose/D-galactose 1-dehydrogenase (EC 1.1.1.-), Rl AraDH. It belongs to the Gfo/Idh/MocA protein family, prefers NADP(+) but uses also NAD(+) as a cofactor, and showed highest catalytic efficiency (k cat/K m) towards L-arabinose, D-galactose and D-fucose. Based on nuclear magnetic resonance (NMR) and modelling studies, the enzyme prefers the α-pyranose form of L-arabinose, and the stable oxidation product detected is L-arabino-1,4-lactone which can, however, open slowly at neutral pH to a linear L-arabonate form. The pH optimum for the enzyme was pH 9, but use of a yeast-in-vivo-like buffer at pH 6.8 indicated that good catalytic efficiency could still be expected in vivo. Expression of the Rl AraDH dehydrogenase in S. cerevisiae, together with the galactose permease Gal2 for L-arabinose uptake, resulted in production of 18 g of L-arabonate per litre, at a rate of 248 mg of L-arabonate per litre per hour, with 86 % of the provided L-arabinose converted to L-arabonate. Expression of a lactonase-encoding gene from Caulobacter crescentus was not necessary for L-arabonate production in yeast.
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16
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Moilanen U, Kellock M, Várnai A, Andberg M, Viikari L. Mechanisms of laccase-mediator treatments improving the enzymatic hydrolysis of pre-treated spruce. Biotechnol Biofuels 2014; 7:177. [PMID: 25648942 PMCID: PMC4297466 DOI: 10.1186/s13068-014-0177-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 12/03/2014] [Indexed: 05/02/2023]
Abstract
BACKGROUND The recalcitrance of softwood to enzymatic hydrolysis is one of the major bottlenecks hindering its profitable use as a raw material for platform sugars. In softwood, the guaiacyl-type lignin is especially problematic, since it is known to bind hydrolytic enzymes non-specifically, rendering them inactive towards cellulose. One approach to improve hydrolysis yields is the modification of lignin and of cellulose structures by laccase-mediator treatments (LMTs). RESULTS LMTs were studied to improve the hydrolysis of steam pre-treated spruce (SPS). Three mediators with three distinct reaction mechanisms (ABTS, HBT, and TEMPO) and one natural mediator (AS, that is, acetosyringone) were tested. Of the studied LMTs, laccase-ABTS treatment improved the degree of hydrolysis by 54%, while acetosyringone and TEMPO increased the hydrolysis yield by 49% and 36%, respectively. On the other hand, laccase-HBT treatment improved the degree of hydrolysis only by 22%, which was in the same order of magnitude as the increase induced by laccase treatment without added mediators (19%). The improvements were due to lignin modification that led to reduced adsorption of endoglucanase Cel5A and cellobiohydrolase Cel7A on lignin. TEMPO was the only mediator that modified cellulose structure by oxidizing hydroxyls at the C6 position to carbonyls and partially further to carboxyls. Oxidation of the reducing end C1 carbonyls was also observed. In contrast to lignin modification, oxidation of cellulose impaired enzymatic hydrolysis. CONCLUSIONS LMTs, in general, improved the enzymatic hydrolysis of SPS. The mechanism of the improvement was shown to be based on reduced adsorption of the main cellulases on SPS lignin rather than cellulose oxidation. In fact, at higher mediator concentrations the advantage of lignin modification in enzymatic saccharification was overcome by the negative effect of cellulose oxidation. For future applications, it would be beneficial to be able to understand and modify the binding properties of lignin in order to decrease unspecific enzyme binding and thus to increase the mobility, action, and recyclability of the hydrolytic enzymes.
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Affiliation(s)
- Ulla Moilanen
- />Department of Food and Environmental Sciences, University of Helsinki, PO Box 27, Helsinki, 00014 Finland
| | - Miriam Kellock
- />Department of Food and Environmental Sciences, University of Helsinki, PO Box 27, Helsinki, 00014 Finland
- />VTT Technical Research Centre of Finland, PO Box 1000, Espoo, 02044 Finland
| | - Anikó Várnai
- />Department of Food and Environmental Sciences, University of Helsinki, PO Box 27, Helsinki, 00014 Finland
- />Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, PO Box 5003, Aas, N-1432 Norway
| | - Martina Andberg
- />VTT Technical Research Centre of Finland, PO Box 1000, Espoo, 02044 Finland
| | - Liisa Viikari
- />Department of Food and Environmental Sciences, University of Helsinki, PO Box 27, Helsinki, 00014 Finland
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17
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Taberman H, Andberg M, Parkkinen T, Richard P, Hakulinen N, Koivula A, Rouvinen J. Purification, crystallization and preliminary X-ray diffraction analysis of a novel keto-deoxy-D-galactarate (KDG) dehydratase from Agrobacterium tumefaciens. Acta Crystallogr F Struct Biol Commun 2013; 70:49-52. [PMID: 24419616 DOI: 10.1107/s2053230x13031361] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Accepted: 11/15/2013] [Indexed: 11/11/2022]
Abstract
D-galacturonic acid is the main component of pectin. It could be used to produce affordable renewable fuels, chemicals and materials through biotechnical conversion. Keto-deoxy-D-galactarate (KDG) dehydratase is an enzyme in the oxidative pathway of D-galacturonic acid in Agrobacterium tumefaciens (At). It converts 3-deoxy-2-keto-L-threo-hexarate to α-ketoglutaric semialdehyde. At KDG dehydratase was crystallized by the hanging-drop vapour-diffusion method. The crystals belonged to the monoclinic space group C2, with unit-cell parameters a = 169.1, b = 117.8, c = 74.3 Å, β = 112.4° and an asymmetric unit of four monomers. X-ray diffraction data were collected to 1.9 Å resolution using synchrotron radiation. The three-dimensional structure of At KDG dehydratase will provide valuable information on the function of the enzyme and will allow it to be engineered for biorefinery-based applications.
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Affiliation(s)
- Helena Taberman
- Department of Chemistry, University of Eastern Finland, PO Box 111, 80101 Joensuu, Finland
| | - Martina Andberg
- VTT Technical Research Centre of Finland, PO Box 1000, 02044 VTT, Finland
| | - Tarja Parkkinen
- Department of Chemistry, University of Eastern Finland, PO Box 111, 80101 Joensuu, Finland
| | - Peter Richard
- VTT Technical Research Centre of Finland, PO Box 1000, 02044 VTT, Finland
| | - Nina Hakulinen
- Department of Chemistry, University of Eastern Finland, PO Box 111, 80101 Joensuu, Finland
| | - Anu Koivula
- VTT Technical Research Centre of Finland, PO Box 1000, 02044 VTT, Finland
| | - Juha Rouvinen
- Department of Chemistry, University of Eastern Finland, PO Box 111, 80101 Joensuu, Finland
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18
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Taberman H, Hakulinen N, Niemi M, Parkkinen T, Jänis J, Andberg M, Koivula A, Rouvinen J. Crystal structure of galactarolactone cycloisomerase from Agrobacterium tumefaciens. Acta Crystallogr A 2013. [DOI: 10.1107/s0108767313097341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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19
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Gourlay K, Hu J, Arantes V, Andberg M, Saloheimo M, Penttilä M, Saddler J. Swollenin aids in the amorphogenesis step during the enzymatic hydrolysis of pretreated biomass. Bioresour Technol 2013; 142:498-503. [PMID: 23759433 DOI: 10.1016/j.biortech.2013.05.053] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Revised: 05/10/2013] [Accepted: 05/15/2013] [Indexed: 05/22/2023]
Abstract
A key limitation in the overall hydrolysis process is the restricted access that the hydrolytic enzymes have due to the macro-and-micro structure of cellulose and its association with hemicellulose and lignin. Previous work has shown that several non-hydrolytic proteins can disrupt cellulose structure and boost the activity of hydrolytic enzymes when purer forms of cellulose are used. In the work reported here, Swollenin primarily disrupted the hemicellulosic fraction of pretreated corn stover, resulting in the solubilisation of monomeric and oligomeric sugars. Although Swollenin showed little synergism when combined with the cellulase monocomponents exoglucanase (CEL7A) and endoglucanase (CEL5A), it showed pronounced synergism with xylanase monocomponents Xylanase GH10 and Xylanase GH11, resulting in the release of significantly more xylose (>300%). It appears that Swollenin plays a role in amorphogenesis and that its primary action is enhancing access to the hemicellulose fraction that limits or masks accessibility to the cellulose component of lignocellulosic substrates.
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Affiliation(s)
- Keith Gourlay
- Forest Products Biotechnology/Bioenergy Group, Department of Wood Science, Faculty of Forestry, University of British Columbia, 2424 Main Mall, Vancouver, BC, Canada V6T 1Z4
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20
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Andberg M, Maaheimo H, Boer H, Penttilä M, Koivula A, Richard P. Characterization of a novel Agrobacterium tumefaciens galactarolactone cycloisomerase enzyme for direct conversion of D-galactarolactone to 3-deoxy-2-keto-L-threo-hexarate. J Biol Chem 2012; 287:17662-17671. [PMID: 22493433 DOI: 10.1074/jbc.m111.335240] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Microorganisms use different pathways for D-galacturonate catabolism. In the known microbial oxidative pathway, D-galacturonate is oxidized to D-galactarolactone, the lactone hydrolyzed to galactarate, which is further converted to 3-deoxy-2-keto-hexarate and α-ketoglutarate. We have shown recently that Agrobacterium tumefaciens strain C58 contains an uronate dehydrogenase (At Udh) that oxidizes D-galacturonic acid to D-galactarolactone. Here we report identification of a novel enzyme from the same A. tumefaciens strain, which we named Galactarolactone cycloisomerase (At Gci) (E.C. 5.5.1.-), for the direct conversion of the D-galactarolactone to 3-deoxy-2-keto-hexarate. The At Gci enzyme is 378 amino acids long and belongs to the mandelate racemase subgroup in the enolase superfamily. At Gci was heterologously expressed in Escherichia coli, and the purified enzyme was found to exist as an octameric form. It is active both on D-galactarolactone and D-glucarolactone, but does not work on the corresponding linear hexaric acid forms. The details of the reaction mechanism were further studied by NMR and optical rotation demonstrating that the reaction product of At Gci from D-galactaro-1,4-lactone and D-glucaro-1,4-lactone conversion is in both cases the L-threo form of 3-deoxy-2-keto-hexarate.
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Affiliation(s)
- Martina Andberg
- VTT Technical Research Centre of Finland, P.O. Box 1000, FIN-02044 VTT, Finland.
| | - Hannu Maaheimo
- VTT Technical Research Centre of Finland, P.O. Box 1000, FIN-02044 VTT, Finland
| | - Harry Boer
- VTT Technical Research Centre of Finland, P.O. Box 1000, FIN-02044 VTT, Finland
| | - Merja Penttilä
- VTT Technical Research Centre of Finland, P.O. Box 1000, FIN-02044 VTT, Finland
| | - Anu Koivula
- VTT Technical Research Centre of Finland, P.O. Box 1000, FIN-02044 VTT, Finland
| | - Peter Richard
- VTT Technical Research Centre of Finland, P.O. Box 1000, FIN-02044 VTT, Finland
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Toivari M, Nygård Y, Kumpula EP, Vehkomäki ML, Benčina M, Valkonen M, Maaheimo H, Andberg M, Koivula A, Ruohonen L, Penttilä M, Wiebe MG. Metabolic engineering of Saccharomyces cerevisiae for bioconversion of D-xylose to D-xylonate. Metab Eng 2012; 14:427-36. [PMID: 22709678 DOI: 10.1016/j.ymben.2012.03.002] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Revised: 01/23/2012] [Accepted: 03/05/2012] [Indexed: 11/30/2022]
Abstract
An NAD(+)-dependent D-xylose dehydrogenase, XylB, from Caulobacter crescentus was expressed in Saccharomyces cerevisiae, resulting in production of 17 ± 2 g D-xylonate l(-1) at 0.23 gl(-1)h(-1) from 23 g D-xylose l(-1) (with glucose and ethanol as co-substrates). D-Xylonate titre and production rate were increased and xylitol production decreased, compared to strains expressing genes encoding T. reesei or pig liver NADP(+)-dependent D-xylose dehydrogenases. D-Xylonate accumulated intracellularly to ∼70 mgg(-1); xylitol to ∼18 mgg(-1). The aldose reductase encoding gene GRE3 was deleted to reduce xylitol production. Cells expressing D-xylonolactone lactonase xylC from C. crescentus with xylB initially produced more extracellular D-xylonate than cells lacking xylC at both pH 5.5 and pH 3, and sustained higher production at pH 3. Cell vitality and viability decreased during D-xylonate production at pH 3.0. An industrial S. cerevisiae strain expressing xylB efficiently produced 43 g D-xylonate l(-1) from 49 g D-xylose l(-1).
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Affiliation(s)
- Mervi Toivari
- VTT, Technical Research Centre of Finland, PO Box 1000, FI-02044 VTT, Espoo, Finland.
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Koivistoinen OM, Arvas M, Headman JR, Andberg M, Penttilä M, Jeffries TW, Richard P. Characterisation of the gene cluster for l-rhamnose catabolism in the yeast Scheffersomyces (Pichia) stipitis. Gene 2011; 492:177-85. [PMID: 22037608 DOI: 10.1016/j.gene.2011.10.031] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Revised: 09/27/2011] [Accepted: 10/11/2011] [Indexed: 01/30/2023]
Abstract
In Scheffersomyces (Pichia) stipitis and related fungal species the genes for L-rhamnose catabolism RHA1, LRA2, LRA3 and LRA4 but not LADH are clustered. We find that located next to the cluster is a transcription factor, TRC1, which is conserved among related species. Our transcriptome analysis shows that all the catabolic genes and all genes of the cluster are up-regulated on L-rhamnose. Among genes that were also up-regulated on L-rhamnose were two transcription factors including the TRC1. In addition, in 16 out of the 32 analysed fungal species only RHA1, LRA2 and LRA3 are physically clustered. The clustering of RHA1, LRA3 and TRC1 is also conserved in species not closely related to S. stipitis. Since the LRA4 is often not part of the cluster and it has several paralogues in L-rhamnose utilising yeasts we analysed the function of one of the paralogues, LRA41 by heterologous expression and biochemical characterization. Lra41p has similar catalytic properties as the Lra4p but the transcript was not up-regulated on L-rhamnose. The RHA1, LRA2, LRA4 and LADH genes were previously characterised in S. stipitis. We expressed the L-rhamnonate dehydratase, Lra3p, in Saccharomyces cerevisiae, estimated the kinetic constants of the protein and showed that it indeed has activity with L-rhamnonate.
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Parkkinen T, Boer H, Jänis J, Andberg M, Penttilä M, Koivula A, Rouvinen J. Crystal structure of uronate dehydrogenase from Agrobacterium tumefaciens. J Biol Chem 2011; 286:27294-300. [PMID: 21676870 PMCID: PMC3149323 DOI: 10.1074/jbc.m111.254854] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Revised: 06/02/2011] [Indexed: 11/06/2022] Open
Abstract
Uronate dehydrogenase from Agrobacterium tumefaciens (AtUdh) belongs to the short-chain dehydrogenase/reductase superfamily and catalyzes the oxidation of D-galacturonic acid and D-glucuronic acid with NAD(+) as a cofactor. We have determined the crystal structures of an apo-form of AtUdh, a ternary form in complex with NADH and product (substrate-soaked structure), and an inactive Y136A mutant in complex with NAD(+). The crystal structures suggest AtUdh to be a homohexamer, which has also been observed to be the major form in solution. The monomer contains a Rossmann fold, essential for nucleotide binding and a common feature of the short-chain dehydrogenase/reductase family enzymes. The ternary complex structure reveals a product, D-galactaro-1,5-lactone, which is bound above the nicotinamide ring. This product rearranges in solution to D-galactaro-1,4-lactone as verified by mass spectrometry analysis, which agrees with our previous NMR study. The crystal structure of the mutant with the catalytic residue Tyr-136 substituted with alanine shows changes in the position of Ile-74 and Ser-75. This probably altered the binding of the nicotinamide end of NAD(+), which was not visible in the electron density map. The structures presented provide novel insights into cofactor and substrate binding and the reaction mechanism of AtUdh. This information can be applied to the design of efficient microbial conversion of D-galacturonic acid-based waste materials.
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Affiliation(s)
- Tarja Parkkinen
- From the Department of Chemistry, University of Eastern Finland, FI-80101 Joensuu, Finland and
| | - Harry Boer
- the VTT Technical Research Centre of Finland, FI-02044 VTT, Finland
| | - Janne Jänis
- From the Department of Chemistry, University of Eastern Finland, FI-80101 Joensuu, Finland and
| | - Martina Andberg
- the VTT Technical Research Centre of Finland, FI-02044 VTT, Finland
| | - Merja Penttilä
- the VTT Technical Research Centre of Finland, FI-02044 VTT, Finland
| | - Anu Koivula
- the VTT Technical Research Centre of Finland, FI-02044 VTT, Finland
| | - Juha Rouvinen
- From the Department of Chemistry, University of Eastern Finland, FI-80101 Joensuu, Finland and
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24
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Kallio JP, Gasparetti C, Andberg M, Boer H, Koivula A, Kruus K, Rouvinen J, Hakulinen N. Crystal structure of an ascomycete fungal laccase from Thielavia arenaria - common structural features of asco-laccases. FEBS J 2011; 278:2283-95. [PMID: 21535408 DOI: 10.1111/j.1742-4658.2011.08146.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Juha P Kallio
- Department of Chemistry, University of Eastern Finland, Joensuu, Finland
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25
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Ercili Cura D, Lantto R, Lille M, Andberg M, Kruus K, Buchert J. Laccase-aided protein modification: Effects on the structural properties of acidified sodium caseinate gels. Int Dairy J 2009. [DOI: 10.1016/j.idairyj.2009.06.007] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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26
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Andberg M, Hakulinen N, Auer S, Saloheimo M, Koivula A, Rouvinen J, Kruus K. Essential role of the C-terminus in Melanocarpus albomyces laccase for enzyme production, catalytic properties and structure. FEBS J 2009; 276:6285-300. [PMID: 19780817 DOI: 10.1111/j.1742-4658.2009.07336.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The C-terminus of the fungal laccase from Melanocarpus albomyces (MaL) is processed during secretion at a processing site conserved among the ascomycete laccases. The three-dimensional structure of MaL has been solved as one of the first complete laccase structures. According to the crystal structure of MaL, the four C-terminal amino acids of the mature protein penetrate into a tunnel leading towards the trinuclear site. The C-terminal carboxylate group forms a hydrogen bond with a side chain of His140, which also coordinates to the type 3 copper. In order to analyze the role of the processed C-terminus, site-directed mutagenesis of the MaL cDNA was performed, and the mutated proteins were expressed in Trichoderma reesei and Saccharomyces cerevisiae. Changes in the C-terminus of MaL caused major defects in protein production in both expression hosts. The deletion of the last four amino acids dramatically affected the activity of the enzyme, as the deletion mutant delDSGL(559) was practically inactive. Detailed characterization of the purified L559A mutant expressed in S. cerevisiae showed the importance of the C-terminal plug for laccase activity, stability, and kinetics. Moreover, the crystal structure of the L559A mutant expressed in S. cerevisiae showed that the C-terminal mutation had clearly affected the trinuclear site geometry. The results in this study clearly confirm the critical role of the last amino acids in the C-terminus of MaL.
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Affiliation(s)
- Martina Andberg
- VTT Technical Research Center of Finland, P.O. Box 1000, FIN-02044 VTT, Finland.
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27
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Kallio JP, Auer S, Jänis J, Andberg M, Kruus K, Rouvinen J, Koivula A, Hakulinen N. Structure-function studies of a Melanocarpus albomyces laccase suggest a pathway for oxidation of phenolic compounds. J Mol Biol 2009; 392:895-909. [PMID: 19563811 DOI: 10.1016/j.jmb.2009.06.053] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2009] [Revised: 06/11/2009] [Accepted: 06/14/2009] [Indexed: 10/20/2022]
Abstract
Melanocarpus albomyces laccase crystals were soaked with 2,6-dimethoxyphenol, a common laccase substrate. Three complex structures from different soaking times were solved. Crystal structures revealed the binding of the original substrate and adducts formed by enzymatic oxidation of the substrate. The dimeric oxidation products were identified by mass spectrometry. In the crystals, a 2,6-dimethoxy-p-benzoquinone and a C-O dimer were observed, whereas a C-C dimer was the main product identified by mass spectrometry. Crystal structures demonstrated that the substrate and/or its oxidation products were bound in the pocket formed by residues Ala191, Pro192, Glu235, Leu363, Phe371, Trp373, Phe427, Leu429, Trp507 and His508. Substrate and adducts were hydrogen-bonded to His508, one of the ligands of type 1 copper. Therefore, this surface-exposed histidine most likely has a role in electron transfer by laccases. Based on our mutagenesis studies, the carboxylic acid residue Glu235 at the bottom of the binding site pocket is also crucial in the oxidation of phenolics. Glu235 may be responsible for the abstraction of a proton from the OH group of the substrate and His508 may extract an electron. In addition, crystal structures revealed a secondary binding site formed through weak dimerization in M. albomyces laccase molecules. This binding site most likely exists only in crystals, when the Phe427 residues are packed against each other.
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Affiliation(s)
- J P Kallio
- Department of Chemistry, University of Joensuu, P.O. Box 111, FIN-80101 Joensuu, Finland
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28
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Lahtinen M, Kruus K, Boer H, Kemell M, Andberg M, Viikari L, Sipilä J. The effect of lignin model compound structure on the rate of oxidation catalyzed by two different fungal laccases. ACTA ACUST UNITED AC 2009. [DOI: 10.1016/j.molcatb.2008.09.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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29
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Hakulinen N, Andberg M, Kallio J, Koivula A, Kruus K, Rouvinen J. A near atomic resolution structure of a Melanocarpus albomyces laccase. J Struct Biol 2008; 162:29-39. [PMID: 18249560 DOI: 10.1016/j.jsb.2007.12.003] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2007] [Revised: 11/28/2007] [Accepted: 12/12/2007] [Indexed: 11/17/2022]
Affiliation(s)
- N Hakulinen
- Department of Chemistry, University of Joensuu, Yliopistonkatu 7, P.O. Box 111, FIN-80101 Joensuu, Finland.
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30
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de Wilde C, Uzan E, Zhou Z, Kruus K, Andberg M, Buchert J, Record E, Asther M, Lomascolo A. Transgenic rice as a novel production system for Melanocarpus and Pycnoporus laccases. Transgenic Res 2007; 17:515-27. [PMID: 17687629 DOI: 10.1007/s11248-007-9124-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2007] [Accepted: 07/19/2007] [Indexed: 10/23/2022]
Abstract
Laccases have numerous biotechnological applications, among them food processing. The widespread use of laccases has increased the demand for an inexpensive and safe source of recombinant enzyme. We explored the use of a rice-based system for the production of two fungal laccases derived from the ascomycete Melanocarpus albomyces and the basidiomycete Pycnoporus cinnabarinus. High-expression levels of active recombinant laccases were achieved by targeting expression to the endosperm of rice seeds. The laccase cDNAs were fused to a plant-derived signal sequence for targeting to the secretory pathway, and placed under the control of a constitutive seed-specific promoter fused to an intron for enhanced expression. This construct enabled the recovery of on average 0.1-1% of soluble laccase in total soluble proteins (TSP). The highest yields of recombinant laccases obtained in rice seeds were 13 and 39 ppm for riceMaL and ricePycL, respectively. The rice-produced laccases were purified and characterized. The wild-type and the recombinant proteins showed similar biochemical features in terms of molecular mass, pI, temperature and optimal pH and the N-terminus was correctly processed. Although presenting lower kinetic parameters, the rice-produced laccases were also suitable for the oxidative cross-linking of a food model substrate [maize-bran feruloylated arabinoxylans (AX)].
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Affiliation(s)
- Chris de Wilde
- CropDesign NV, a BASF Plant Science Company, Technologiepark 3, Zwijnaarde-Gent, Belgium
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31
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Andberg M, Jäntti J, Heilimo S, Pihkala P, Paananen A, Koskinen AMP, Söderlund H, Linder MB. Cleavage of recombinant proteins at poly-His sequences by Co(II) and Cu(II). Protein Sci 2007; 16:1751-61. [PMID: 17600148 PMCID: PMC2203371 DOI: 10.1110/ps.072846407] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Improved ways to cleave peptide chains at engineered sites easily and specifically would form useful tools for biochemical research. Uses of such methods include the activation or inactivation of enzymes or the removal of tags for enhancement of recombinant protein expression or tags used for purification of recombinant proteins. In this work we show by gel electrophoresis and mass spectroscopy that salts of Co(II) and Cu(II) can be used to cleave fusion proteins specifically at sites where sequences of His residues have been introduced by protein engineering. The His residues could be either consecutive or spaced with other amino acids in between. The cleavage reaction required the presence of low concentrations of ascorbate and in the case of Cu(II) also hydrogen peroxide. The amount of metal ions required for cleavage was very low; in the case of Cu(II) only one to two molar equivalents of Cu(II) to protein was required. In the case of Co(II), 10 molar equivalents gave optimal cleavage. The reaction occurred within minutes, at a wide pH range, and efficiently at temperatures ranging from 0 degrees C to 70 degrees C. The work described here can also have implications for understanding protein stability in vitro and in vivo.
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Affiliation(s)
- Martina Andberg
- VTT Technical Research Centre of Finland, Espoo FIN-02044 VTT, Finland
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32
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Levasseur A, Saloheimo M, Navarro D, Andberg M, Monot F, Nakari-Setälä T, Asther M, Record E. Production of a chimeric enzyme tool associating the Trichoderma reesei swollenin with the Aspergillus niger feruloyl esterase A for release of ferulic acid. Appl Microbiol Biotechnol 2006; 73:872-80. [PMID: 16957894 DOI: 10.1007/s00253-006-0546-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2006] [Revised: 05/30/2006] [Accepted: 06/19/2006] [Indexed: 10/24/2022]
Abstract
The main goals of this work were to produce the fusion protein of the Trichoderma reesei swollenin I (SWOI) and Aspergillus niger feruloyl esterase A (FAEA) and to study the effect of the physical association of the fusion partners on the efficiency of the enzyme. The fusion protein was produced up to 25 mg l(-1) in the T. reesei strains Rut-C30 and CL847. In parallel, FAEA alone was produced for use as a control protein in application tests. Recombinant FAEA and SWOI-FAEA were purified to homogeneity and characterized. The biochemical and kinetic characteristics of the two recombinant proteins were found to be similar to those of native FAEA, except for the temperature stability and specific activity of the SWOI-FAEA. Finally, the SWOI-FAEA protein was tested for release of ferulic acid from wheat bran. A period of 24 h of enzymatic hydrolysis with the SWOI-FAEA improved the efficiency of ferulic acid release by 50% compared with the results obtained using the free FAEA and SWOI. Ferulic acid is used as an antioxidant and flavor precursor in the food and pharmaceutical industries. This is the first report of a potential application of the SWOI protein fused with an enzyme of industrial interest.
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Affiliation(s)
- Anthony Levasseur
- UMR 1163 INRA/Universités de Provence et de la Méditerranée de Biotechnologie des Champignons Filamenteux, IFR-IBAIM, 163 avenue de Luminy, Case Postale 925, 13288 Marseille Cedex 09, France
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33
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Abstract
Leukotriene (LT) A(4) hydrolase is a bifunctional zinc metalloenzyme, which converts LTA(4) into the neutrophil chemoattractant LTB(4) and also exhibits an anion-dependent aminopeptidase activity. In the x-ray crystal structure of LTA(4) hydrolase, Arg(563) and Lys(565) are found at the entrance of the active center. Here we report that replacement of Arg(563), but not Lys(565), leads to complete abrogation of the epoxide hydrolase activity. However, mutations of Arg(563) do not seem to affect substrate binding strength, because values of K(i) for LTA(4) are almost identical for wild type and (R563K)LTA(4) hydrolase. These results are supported by the 2.3-A crystal structure of (R563A)LTA(4) hydrolase, which does not reveal structural changes that can explain the complete loss of enzyme function. For the aminopeptidase reaction, mutations of Arg(563) reduce the catalytic activity (V(max) = 0.3-20%), whereas mutations of Lys(565) have limited effect on catalysis (V(max) = 58-108%). However, in (K565A)- and (K565M)LTA(4) hydrolase, i.e. mutants lacking a positive charge, values of the Michaelis constant for alanine-p-nitroanilide increase significantly (K(m) = 480-640%). Together, our data indicate that Arg(563) plays an unexpected, critical role in the epoxide hydrolase reaction, presumably in the positioning of the carboxylate tail to ensure perfect substrate alignment along the catalytic elements of the active site. In the aminopeptidase reaction, Arg(563) and Lys(565) seem to cooperate to provide sufficient binding strength and productive alignment of the substrate. In conclusion, Arg(563) and Lys(565) possess distinct roles as carboxylate recognition sites for two chemically different substrates, each of which is turned over in separate enzymatic reactions catalyzed by LTA(4) hydrolase.
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Affiliation(s)
- Peter C Rudberg
- Department of Medical Biochemistry and Biophysics, Division of Chemistry II, Karolinska Institutet, S-171 77 Stockholm, Sweden
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34
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Andberg M, Hamberg M, Haeggström JZ. Evidence for a carbocation intermediate in the enzymatic transformation of leukotriene A4 into leukotriene B4. Adv Exp Med Biol 2000; 469:319-25. [PMID: 10667348 DOI: 10.1007/978-1-4615-4793-8_47] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Affiliation(s)
- M Andberg
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
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35
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Andberg M, Wetterholm A, Medina JF, Haeggström JZ. Leukotriene A4 hydrolase: a critical role of glutamic acid-296 for the binding of bestatin. Biochem J 2000; 345 Pt 3:621-5. [PMID: 10642521 PMCID: PMC1220797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
Leukotriene A(4) hydrolase is a bifunctional Zn(2+)-containing enzyme catalysing the formation of the potent chemotaxin leukotriene B(4). From an analysis of three mutants of Glu-296 we have found that this catalytic residue is critical for the binding of bestatin, a classical aminopeptidase inhibitor. For bestatin, but not for three other tight-binding inhibitors, the IC(50) values for inhibition of the epoxide hydrolase activity decreased in the mutants to 0.7-0.003% of the control. Hence Glu-296 is an important structural determinant for binding of bestatin to leukotriene A(4) hydrolase; this conclusion might also apply to other members of the M1 family of metallopeptidases.
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Affiliation(s)
- M Andberg
- Department of Medical Biochemistry and Biophysics, Division of Chemistry II, Karolinska Institutet, S-171 77 Stockholm, Sweden
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36
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Abstract
The bifunctional leukotriene A4 hydrolase catalyzes the final step in the biosynthesis of the proinflammatory leukotriene B4. During exposure to the substrate leukotriene A4, a labile allylic epoxide, the enzyme is gradually inactivated as a consequence of the covalent binding of leukotriene A4 to the active site. This phenomenon, commonly referred to as suicide inactivation, has previously been rationalized as a mechanism-based process in which the enzyme converts the substrate to a highly reactive intermediate within an activated enzyme-substrate complex that partitions between covalent bond formation (inactivation) and catalysis. To further explore the molecular mechanism of the self-inactivation of leukotriene A4 hydrolase by leukotriene A4, we prepared and analyzed mutated forms of the enzyme that were either catalytically incompetent or fully active but resistant toward substrate-mediated inactivation. These mutants were treated with leukotriene A4 and leukotriene A4 methyl and ethyl esters and subjected to differential peptide mapping and enzyme activity determinations, which showed that inactivation and/or covalent modification can be completely dissociated from catalysis. Our results, together with recent findings described in the literature, argue against a mechanism-based model for suicide inactivation. We conclude that the collected data on the substrate-mediated inactivation of leukotriene A4 hydrolase best conforms to an affinity-labeling mechanism.
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Affiliation(s)
- M J Mueller
- Department of Medical Biochemistry and Biophysics, Division of Chemistry II, Karolinska Institutet, S-171 77 Stockholm, Sweden
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37
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Affiliation(s)
- M Andberg
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
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38
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Abstract
We compared the ability of 48 patients with Parkinson's disease (PD) (24 mild, 24 moderate) and 35 controls to remain oriented to the starting position after being transported passively in a wheelchair in two conditions: visual and vestibular. The moderate PD group demonstrated the poorest performance in both sensory conditions. The visual condition discriminated between the mild PD group and the controls, but both groups had similar performance in the vestibular condition. Poor performance of the PD group in the visual condition and controls in the vestibular condition correlated significantly with poor performance on selected balance tests. Poor performance in the visual condition correlated significantly with poor performance on judgment of line orientation in the mild PD group. Spatial updating, or maintaining a sense of orientation while being moved in the environment, may be impaired in PD and should be investigated as a possible contributing factor to problems with spatial orientation noted clinically in some patients.
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