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Gojkovic Z, Simansky S, Sanabria A, Márová I, Garbayo I, Vílchez C. Interaction of Naturally Occurring Phytoplankton with the Biogeochemical Cycling of Mercury in Aquatic Environments and Its Effects on Global Hg Pollution and Public Health. Microorganisms 2023; 11:2034. [PMID: 37630594 PMCID: PMC10458190 DOI: 10.3390/microorganisms11082034] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Revised: 08/02/2023] [Accepted: 08/05/2023] [Indexed: 08/27/2023] Open
Abstract
The biogeochemical cycling of mercury in aquatic environments is a complex process driven by various factors, such as ambient temperature, seasonal variations, methylating bacteria activity, dissolved oxygen levels, and Hg interaction with dissolved organic matter (DOM). As a consequence, part of the Hg contamination from anthropogenic activity that was buried in sediments is reinserted into water columns mainly in highly toxic organic Hg forms (methylmercury, dimethylmercury, etc.). This is especially prominent in the coastal shallow waters of industrial regions worldwide. The main entrance point of these highly toxic Hg forms in the aquatic food web is the naturally occurring phytoplankton. Hg availability, intake, effect on population size, cell toxicity, eventual biotransformation, and intracellular stability in phytoplankton are of the greatest importance for human health, having in mind that such Hg incorporated inside the phytoplankton cells due to biomagnification effects eventually ends up in aquatic wildlife, fish, seafood, and in the human diet. This review summarizes recent findings on the topic of organic Hg form interaction with natural phytoplankton and offers new insight into the matter with possible directions of future research for the prevention of Hg biomagnification in the scope of climate change and global pollution increase scenarios.
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Affiliation(s)
- Zivan Gojkovic
- Algae Biotechnology Group, CIDERTA, University of Huelva, 21007 Huelva, Spain; (A.S.); (I.G.); (C.V.)
| | - Samuel Simansky
- Faculty of Chemistry, Brno University of Technology, Purkynova 118, 61200 Brno, Czech Republic; (S.S.); (I.M.)
| | - Alain Sanabria
- Algae Biotechnology Group, CIDERTA, University of Huelva, 21007 Huelva, Spain; (A.S.); (I.G.); (C.V.)
| | - Ivana Márová
- Faculty of Chemistry, Brno University of Technology, Purkynova 118, 61200 Brno, Czech Republic; (S.S.); (I.M.)
| | - Inés Garbayo
- Algae Biotechnology Group, CIDERTA, University of Huelva, 21007 Huelva, Spain; (A.S.); (I.G.); (C.V.)
| | - Carlos Vílchez
- Algae Biotechnology Group, CIDERTA, University of Huelva, 21007 Huelva, Spain; (A.S.); (I.G.); (C.V.)
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Lindberg RH, Namazkar S, Lage S, Östman M, Gojkovic Z, Funk C, Gentili FG, Tysklind M. Fate of active pharmaceutical ingredients in a northern high-rate algal pond fed with municipal wastewater. Chemosphere 2021; 271:129763. [PMID: 33736225 DOI: 10.1016/j.chemosphere.2021.129763] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [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: 11/27/2020] [Revised: 01/12/2021] [Accepted: 01/20/2021] [Indexed: 05/25/2023]
Abstract
Active pharmaceutical ingredients (APIs) are vital to human health and welfare, but following therapeutic use, they may pose a potential ecological risk if discharged into the environment. Today's conventional municipal wastewater treatment plants are not designed to remove APIs specifically, and various techniques, preferably cost-effective and environmentally friendly, are being developed and evaluated. Microalgae-based treatment of wastewater is a sustainable and low-cost approach to remove nutrients and emerging contaminants. In this study, a North Sweden high-rate algal pond (HRAP) using municipal untreated wastewater as medium, was investigated in terms of API distribution and fate. Three six-day batches were prepared during 18 days and a total of 36 APIs were quantified within the HRAP of which 14 were removed from the aqueous phase above 50% and seven removed above 90% of their initial concentrations. Twelve APIs of a hydrophobic nature were mostly associated with the algal biomass that was harvested at the end of each batch. HRAPs treatment successfully removed 69% of studied APIs (25 of 36 studied) in six day time. The distribution of various APIs between the aqueous phase and biomass suggested that several removal mechanisms may occur, such as hydrophobicity driven removal, passive biosorption and active bioaccumulation.
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Affiliation(s)
| | - Shahla Namazkar
- Department of Environmental Science, Stockholm University, 106 91, Stockholm, Sweden
| | - Sandra Lage
- Department of Environmental Science, Stockholm University, 106 91, Stockholm, Sweden; Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, 901 83, Umeå, Sweden
| | - Marcus Östman
- Department of Chemistry, Umeå University, 901 87, Umeå, Sweden; Department of Medical Biosciences, Umeå University, 901 85, Umeå, Sweden
| | - Zivan Gojkovic
- Department of Chemistry, Umeå University, 901 87, Umeå, Sweden
| | - Christiane Funk
- Department of Chemistry, Umeå University, 901 87, Umeå, Sweden
| | - Francesco G Gentili
- Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, 901 83, Umeå, Sweden
| | - Mats Tysklind
- Department of Chemistry, Umeå University, 901 87, Umeå, Sweden
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Gojkovic Z, Lu Y, Ferro L, Toffolo A, Funk C. Modeling biomass production during progressive nitrogen starvation by North Swedish green microalgae. ALGAL RES 2020. [DOI: 10.1016/j.algal.2020.101835] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Gojkovic Z, Shchukarev A, Ramstedt M, Funk C. Cryogenic X-ray photoelectron spectroscopy determines surface composition of algal cells and gives insights into their spontaneous sedimentation. ALGAL RES 2020. [DOI: 10.1016/j.algal.2020.101836] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Skrobonja A, Gojkovic Z, Soerensen AL, Westlund PO, Funk C, Björn E. Uptake Kinetics of Methylmercury in a Freshwater Alga Exposed to Methylmercury Complexes with Environmentally Relevant Thiols. Environ Sci Technol 2019; 53:13757-13766. [PMID: 31682417 DOI: 10.1021/acs.est.9b05164] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Cellular uptake of dissolved methylmercury (MeHg) by phytoplankton is the most important point of entry for MeHg into aquatic food webs. However, the process is not fully understood. In this study we investigated the influence of chemical speciation on rate constants for MeHg accumulation by the freshwater green microalga Selenastrum capricornutum. We used six MeHg-thiol complexes with moderate but important structural differences commonly found in the environment. Rate constants for MeHg interactions with cells were determined for the MeHg-thiol treatments and a control assay containing the thermodynamically less stable MeHgOH complex. We found both elevated amounts of MeHg associated with whole cells and higher MeHg association rate constants in the control compared to the thiol treatments. Furthermore, the association rate constants were lower when algae were exposed to MeHg complexes with thiols of larger size and more "branched" chemical structure compared to complexes with simpler structure. The results further demonstrated that the thermodynamic stability and chemical structure of MeHg complexes in the medium is an important controlling factor for the rate of MeHg interactions with the cell surface, but not for the MeHg exchange rate across the membrane. Our results are in line with uptake mechanisms involving formation of MeHg complexes with cell surface ligands prior to internalization.
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Affiliation(s)
| | - Zivan Gojkovic
- Umeå University , Department of Chemistry , SE-901 87 Umeå , Sweden
| | - Anne L Soerensen
- Stockholm University , Department of Environmental Science and Analytical Chemistry , SE-106 97 Stockholm , Sweden
| | | | - Christiane Funk
- Umeå University , Department of Chemistry , SE-901 87 Umeå , Sweden
| | - Erik Björn
- Umeå University , Department of Chemistry , SE-901 87 Umeå , Sweden
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Martínez JM, Gojkovic Z, Ferro L, Maza M, Álvarez I, Raso J, Funk C. Use of pulsed electric field permeabilization to extract astaxanthin from the Nordic microalga Haematococcus pluvialis. Bioresour Technol 2019; 289:121694. [PMID: 31254897 DOI: 10.1016/j.biortech.2019.121694] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [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: 05/06/2019] [Revised: 06/19/2019] [Accepted: 06/20/2019] [Indexed: 05/28/2023]
Abstract
The Nordic microalgal strain Haematococcus pluvialis was exposed to various stress conditions to induce astaxanthin accumulation. Highest carotenoid content (19.1 mg·g-1dw) was achieved in nitrogen-free culture medium at a high light intensity. The efficiency of Pulsed Electric Field (PEF) pre-treatment of stressed fresh biomass of H. pluvialis followed by incubation in the growth medium was compared to classical disruption methods (bead-beating, freezing-thawing, thermal treatment or ultrasound) for the subsequent extraction of astaxanthin in ethanol. N-starved cells treated with PEF followed by aqueous incubation for 6 h resulted in extraction of 96% (18.3 mgcar·gdw-1) of the total carotenoid content compared to 80% (15.3 mgcar·gdw-1) using other physical methods. The proportion of free forms of astaxanthin was higher in PEF-treated samples compared to mechanical disruption, suggesting PEF triggering an esterase activity. PEF pre-treatment of the cells followed by incubation in growth medium improved astaxanthin extraction in the eco-friendly solvent ethanol.
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Affiliation(s)
- Juan Manuel Martínez
- Department of Chemistry, Umeå University, 90187 Umeå, Sweden; Food Technology, Facultad de Veterinaria, Instituto Agroalimentario de Aragón-IA2 (Universidad de Zaragoza-CITA), Zaragoza, Spain
| | - Zivan Gojkovic
- Department of Chemistry, Umeå University, 90187 Umeå, Sweden
| | - Lorenza Ferro
- Department of Chemistry, Umeå University, 90187 Umeå, Sweden
| | - Marcos Maza
- Food Technology, Facultad de Veterinaria, Instituto Agroalimentario de Aragón-IA2 (Universidad de Zaragoza-CITA), Zaragoza, Spain
| | - Ignacio Álvarez
- Food Technology, Facultad de Veterinaria, Instituto Agroalimentario de Aragón-IA2 (Universidad de Zaragoza-CITA), Zaragoza, Spain
| | - Javier Raso
- Food Technology, Facultad de Veterinaria, Instituto Agroalimentario de Aragón-IA2 (Universidad de Zaragoza-CITA), Zaragoza, Spain
| | - Christiane Funk
- Department of Chemistry, Umeå University, 90187 Umeå, Sweden.
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Ferro L, Gojkovic Z, Gorzsás A, Funk C. Statistical Methods for Rapid Quantification of Proteins, Lipids, and Carbohydrates in Nordic Microalgal Species Using ATR-FTIR Spectroscopy. Molecules 2019; 24:molecules24183237. [PMID: 31492012 PMCID: PMC6767194 DOI: 10.3390/molecules24183237] [Citation(s) in RCA: 23] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 09/03/2019] [Accepted: 09/03/2019] [Indexed: 11/16/2022] Open
Abstract
Attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy is a simple, cheap, and fast method to collect chemical compositional information from microalgae. However, (semi)quantitative evaluation of the collected data can be daunting. In this work, ATR-FTIR spectroscopy was used to monitor changes of protein, lipid, and carbohydrate content in seven green microalgae grown under nitrogen starvation. Three statistical methods-univariate linear regression analysis (ULRA), orthogonal partial least squares (OPLS), and multivariate curve resolution-alternating least squares (MCR-ALS)-were compared in their ability to model and predict the concentration of these compounds in the biomass. OPLS was found superior, since it i) included all three compounds simultaneously; ii) explained variations in the data very well; iii) had excellent prediction accuracy for proteins and lipids, and acceptable for carbohydrates; and iv) was able to discriminate samples based on cultivation stage and type of storage compounds accumulated in the cells. ULRA models worked well for the determination of proteins and lipids, but carbohydrates could only be estimated if already determined protein contents were used for scaling. Results obtained by MCR-ALS were similar to ULRA, however, this method is considerably easier to perform and interpret than the more abstract statistical/chemometric methods. FTIR-spectroscopy-based models allow high-throughput, cost-effective, and rapid estimation of biomass composition of green microalgae.
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Affiliation(s)
- Lorenza Ferro
- Department of Chemistry, Umeå University, 901 87 Umeå, Sweden.
| | - Zivan Gojkovic
- Department of Chemistry, Umeå University, 901 87 Umeå, Sweden.
| | - András Gorzsás
- Department of Chemistry, Umeå University, 901 87 Umeå, Sweden.
| | - Christiane Funk
- Department of Chemistry, Umeå University, 901 87 Umeå, Sweden.
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Gojkovic Z, Lindberg RH, Tysklind M, Funk C. Northern green algae have the capacity to remove active pharmaceutical ingredients. Ecotoxicol Environ Saf 2019; 170:644-656. [PMID: 30579165 DOI: 10.1016/j.ecoenv.2018.12.032] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [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: 07/17/2018] [Revised: 12/07/2018] [Accepted: 12/11/2018] [Indexed: 05/28/2023]
Abstract
Eight recently isolated microalgal species from Northern Sweden and the culture collection strain Scenedesmus obliquus RISE (UTEX 417) were tested for their ability to remove 19 pharmaceuticals from growth medium upon cultivation in short light path, flat panel photobioreactors. While the growth of one algal species, Chlorella sorokiniana B1-1, was completely inhibited by the addition of pharmaceuticals, and the one of Scenedesmus sp. B2-2 was strongly inhibited, the other algal strains grew well and produced biomass. In general, lipophilic compounds were removed highly efficient from the culture medium by the microalgae (>70% in average within 2 days). The most lipophilic compounds Biperiden, Trihexyphenidyl, Clomipramine and Amitriptyline significantly accumulated in the biomass of most algal species, with a positive correlation between accumulation and their total biomass content. More persistent in the growth medium were hydrophilic compounds like Caffeine, Fluconazole, Trimetoprim, Codeine, Carbamazepin, Oxazepam and Tramadol, which were detected in amounts of above 60% in average after algal treatment. While Coelastrella sp. 3-4 and Coelastrum astroideum RW10 were most efficient to accumulate certain compounds in their biomass, two algae species, Chlorella vulgaris 13-1 and Chlorella saccharophila RNY, were not only highly efficient in removing all 19 pharmaceuticals from the growth medium within 12 days, at the same time only small amounts of these compounds accumulated in their biomass allowing its further use. Chlorella vulgaris 13-1 was able to remove most compounds within 6 days of growth, while Chlorella saccharophila RNY needed 8-10 days."Wild" Nordic microalgae therefore are able to remove active pharmaceutical ingredients, equally or more efficient than the investigated culture collection strain, thereby demonstrating their possible use in sustainable wastewater reclamation in Nordic conditions.
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Affiliation(s)
- Zivan Gojkovic
- Department of Chemistry, Umeå University, S-90187 Umeå, Sweden
| | | | - Mats Tysklind
- Department of Chemistry, Umeå University, S-90187 Umeå, Sweden
| | - Christiane Funk
- Department of Chemistry, Umeå University, S-90187 Umeå, Sweden.
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Vještica M, Jungic S, Gojkovic Z, Rakita I, Berendika J, Šipka D. P-138 Is HER2 positivity gastric cancer good prognostic sign? - Our experiences. Ann Oncol 2016. [DOI: 10.1093/annonc/mdw199.132] [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: 11/13/2022] Open
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10
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Gojkovic Z, Marova I, Matouskova P, Obruca S, Miloslav P. Use of ultrasonic spectroscopy and viscosimetry for the characterization of chicken skin collagen in comparison with collagens from other animal tissues. Prep Biochem Biotechnol 2015; 44:761-71. [PMID: 24279885 DOI: 10.1080/10826068.2013.867869] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Use of traditional sources of collagen such as pork, bovine, and carp has some limitations. Chicken skin can be valuable alternative. In this work collagen was isolated from chicken skin using a modified procedure. Molecular properties of chicken collagen were analyzed and compared to collagen from other animal skins. Acid-soluble collagen type I was obtained with a yield of 25% and water content around 67%. Viscosimetry and ultrasonic spectroscopy were newly used for molecular characterization. By ultrasonic attenuation measurements, a pre-aggregation phase in the interval from 20°C to 27°C was observed, which is a proof of disaggregation and liquefaction. From 40°C upward, the liquefaction process finishes and aggregation continues. In a bovine sample this phenomenon starts at 40°C, in chicken at 50°C, and continues until 70°C. By viscosimetry, the denaturation temperature was confirmed as 40°C for bovine and 50°C for chicken collagen. Chicken collagen has a two times higher lysine level than bovine, which provides molecular stability side-chain interactions. With regard to higher thermal stability and favorable amino acid composition, waste chicken skin has the potential to be an excellent alternative source of raw collagen with applications in the food industry and biomedicine.
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Affiliation(s)
- Zivan Gojkovic
- a Materials Research Centre, Faculty of Chemistry , Brno University of Technology , Brno , Czech Republic
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Maksimovic S, Jakovljevic B, Gojkovic Z. 369 Association of Triple-negative Breast Cancer with Extracapsular Extension of Axillary Lymph Node Metastasis. Eur J Cancer 2012. [DOI: 10.1016/s0959-8049(12)70435-5] [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: 11/29/2022]
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Maksimovic S, Gojkovic Z, Jakovljevic B, Maksimovic Z. 602 Extracapsular extension of axillary lymph node metastases in HER-2 receptor positive and negative breast cancers: prognostic importance. EJC Suppl 2010. [DOI: 10.1016/s1359-6349(10)71403-8] [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: 10/19/2022] Open
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Maksimovic S, Jakovljevic B, Gojkovic Z. 5037 Prognostic importance the extracapsular extension of axillary lymph node metastases in HER-2 receptor positive and negative breast cancers. EJC Suppl 2009. [DOI: 10.1016/s1359-6349(09)70929-2] [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: 10/20/2022] Open
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Knecht W, Rozpedowska E, Le Breton C, Willer M, Gojkovic Z, Sandrini MPB, Joergensen T, Hasholt L, Munch-Petersen B, Piskur J. Drosophila deoxyribonucleoside kinase mutants with enhanced ability to phosphorylate purine analogs. Gene Ther 2007; 14:1278-86. [PMID: 17581598 DOI: 10.1038/sj.gt.3302982] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [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: 11/09/2022]
Abstract
Transduced deoxyribonucleoside kinases (dNK) can be used to kill recipient cells in combination with nucleoside prodrugs. The Drosophila melanogaster multisubstrate dNK (Dm-dNK) displays a superior turnover rate and has a great plasticity regarding its substrates. We used directed evolution to create Dm-dNK mutants with increased specificity for several nucleoside analogs (NAs) used as anticancer or antiviral drugs. Four mutants were characterized for the ability to sensitize Escherichia coli toward analogs and for their substrate specificity and kinetic parameters. The mutants had a reduced ability to phosphorylate pyrimidines, while the ability to phosphorylate purine analogs was relatively similar to the wild-type enzyme. We selected two mutants, for expression in the osteosarcoma 143B, the glioblastoma U-87M-G and the breast cancer MCF7 cell lines. The sensitivities of the transduced cell lines in the presence of the NAs fludarabine (F-AraA), cladribine (CdA), vidarabine and cytarabine were compared to the parental cell lines. The sensitivity of 143B cells was increased by 470-fold in the presence of CdA and of U-87M-G cells by 435-fold in the presence of F-AraA. We also show that a choice of the selection and screening system plays a crucial role when optimizing suicide genes by directed evolution.
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Affiliation(s)
- W Knecht
- BioCentrum-DTU, Technical University of Denmark, Lyngby, Denmark
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Maksimovic S, Gojkovic Z, Opric M. Positive axillary lymph node metastases in T1–T3 breast cancer: prognostic value of extracapsular extension. Breast Cancer Res 2007. [DOI: 10.1186/bcr1716] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [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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Gojkovic Z, Jahnke K, Schnackerz KD, Piskur J. PYD2 encodes 5,6-dihydropyrimidine amidohydrolase, which participates in a novel fungal catabolic pathway. J Mol Biol 2000; 295:1073-87. [PMID: 10656811 DOI: 10.1006/jmbi.1999.3393] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [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: 11/22/2022]
Abstract
Most fungi cannot use pyrimidines or their degradation products as the sole nitrogen source. Previously, we screened several yeasts for their ability to catabolise pyrimidines. One of them, Saccharomyces kluyveri, was able to degrade the majority of pyrimidines. Here, a series of molecular techniques have been modified to clone pyrimidine catabolic genes, study their expression and purify the corresponding enzymes from this yeast. The pyd2-1 mutant, which lacked the 5,6-dihydropyrimidine amidohydrolase (DHPase) activity, was transformed with wild-type S. kluyveri genomic library. The complementing plasmid contained the full sequence of the PYD2 gene, which exhibited a high level of homology with mammalian DHPases and bacterial hydantoinases. The organisation of PYD2 showed a couple of specific features. The 542-codons open reading frame was interrupted by a 63 bp intron, which does not contain the Saccharomyces cerevisiae branch-point sequence, and the transcripts contained a long 5' untranslated leader with five or six AUG codons. The derived amino acid sequence showed similarities with dihydroorotases, allantoinases and uricases from various organisms. Surprisingly, the URA4 gene from S. cerevisiae, which encodes dihydroorotase, shows greater similarity to PYD2 and other catabolic enzymes than to dihydroorotases from several other non-fungal organisms. The S. kluyveri DHPase was purified to homogeneity and sequencing of the N-terminal region revealed that the purified enzyme corresponds to the PYD2 gene product. The enzyme is a tetramer, likely consisting of similar if not identical subunits each with a molecular mass of 59 kDa. The S. kluyveri DHPase was capable of catalysing both dihydrouracil and dihydrothymine degradation, presumably by the same reaction mechanism as that described for mammalian DHPase. On the other hand, the regulation of the yeast PYD2 gene and DHPase seem to be different from that in other organisms. DHPase activity and Northern analysis demonstrated that PYD2 expression is inducible by dihydrouracil, though not by uracil. Apparently, dihydrouracil and DHPase represent an important regulatory checkpoint of the pyrimidine catabolic pathway in S. kluyveri.
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Affiliation(s)
- Z Gojkovic
- Department of Microbiology Building 301, Technical University of Denmark, Lyngby, DK-2800, Denmark
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Aleksenko A, Liu W, Gojkovic Z, Nielsen J, Piskur J. Structural and transcriptional analysis of the pyrABCN, pyrD and pyrF genes in Aspergillus nidulans and the evolutionary origin of fungal dihydroorotases. Mol Microbiol 1999; 33:599-611. [PMID: 10417650 DOI: 10.1046/j.1365-2958.1999.01507.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [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: 11/20/2022]
Abstract
The six biochemical steps of the de novo pyrimidine biosynthesis pathway are conserved in all known organisms. However, in animals and fungi, unlike prokaryotes, at least the first two activities are grouped on a multifunctional enzyme. Here, we report cloning, mapping and transcriptional characterization of some pyrimidine biosynthesis genes in the filamentous fungus Aspergillus nidulans. The first two steps of the pathway are performed by a multifunctional enzyme comprising the activities of carbamoyl phosphate synthetase (CPSase) and aspartate transcarbamylase (ATCase). This polypeptide is encoded by a 7 kbp cluster gene, pyrABCN, which has a high degree of nucleotide identity with the Ura2 gene in Saccharomyces cerevisiae. The enzyme of the third step, dihydroorotase (DHOase), is encoded by a separate locus, pyrD. However, the pyrABCN gene apparently contains an evolutionary remnant of a DHOase-encoding sequence, similarly to the Ura2 gene of Saccharomyces cerevisiae. The pyrABCN gene is transcribed as a single 7 kb mRNA species. The level of transcripts of pyrABCN, pyrD and, to a lesser degree, pyrF genes responds to the presence of exogenous pyrimidines and to the conditions of pyrimidine starvation. Derepression of pyrABCN and pyrD under pyrimidine starvation is noticeably enhanced in pyrE mutants that accumulate dihydroorotic acid. The pyrABCN gene maps to the distal portion of the right arm of the chromosome VIII, whereas the pyrD gene, in contrast to early genetic data, is closely linked to the brlA gene and located to the right of it. Our data on mitotic recombination should help to verify the genetic map of the chromosome VIII. Comparison of amino acid sequences of active dihydroorotases with related enzymes and with their non-functional homologues in yeast and Aspergillus indicates that the active dihydroorotases from fungi are more similar to ureases and enzymes of the pyrimidine degradation pathway. The 'silent' dihydroorotase domains of the multifunctional enzymes from fungi and active DHOase domains of the multifunctional enzymes in higher eukaryotes are more closely related to bacterial dehydroorotases.
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Affiliation(s)
- A Aleksenko
- Center for Process Biotechnology, DTU, Lyngby, Denmark.
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Affiliation(s)
- Z Gojkovic
- Department of Microbiology, Technical University of Denmark, Lyngby, Denmark
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Gojkovic Z, Piskur J. A new model organism for studying catabolism of pyrimidines and purines. Clin Biochem 1997. [DOI: 10.1016/s0009-9120(97)87762-4] [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: 11/25/2022]
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Piskur J, Søndergaard L, Gojkovic Z, Stokbro B, Hjulsager C, Davidson J, DeMoll E, Rawls J, Bahn E. Observed resistance to pyrimidine analogs and sensitivity to uracil in Drosophila is attributed to deregulation of pyrimidine metabolism. Adv Exp Med Biol 1995; 370:559-65. [PMID: 7660969 DOI: 10.1007/978-1-4615-2584-4_118] [Citation(s) in RCA: 3] [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: 01/26/2023]
Affiliation(s)
- J Piskur
- Department of Genetics, University of Copenhagen, Denmark
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