| 1. |
- Kreisel, Katrin, 1991, et al.
(författare)
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DNA polymerase η contributes to genome-wide lagging strand synthesis.
- 2019
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Ingår i: Nucleic acids research. - : Oxford University Press (OUP). - 1362-4962 .- 0305-1048. ; 47:5, s. 2425-2435
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Tidskriftsartikel (refereegranskat)abstract
- DNA polymerase η (pol η) is best known for its ability to bypass UV-induced thymine-thymine (T-T) dimers and other bulky DNA lesions, but pol ηalso has other cellular roles. Here, we present evidence that pol η competes with DNA polymerases α and δfor the synthesis of the lagging strand genome-wide, where it also shows a preference for T-T in the DNA template. Moreover, we found that the C-terminus of pol η,which contains a PCNA-Interacting Protein motif is required for pol ηto function in lagging strand synthesis. Finally, we provide evidence that a pol η dependent signature is also found to be lagging strand specific in patients with skin cancer. Taken together, these findings provide insight into the physiological role of DNA synthesis by pol η and have implications for our understanding of how our genome is replicated to avoid mutagenesis, genome instability and cancer.
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| 2. |
- Peng, Martin, et al.
(författare)
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3D-Printed Phenacrylate Decarboxylase Flow Reactors for the Chemoenzymatic Synthesis of 4-Hydroxystilbene
- 2019
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Ingår i: Chemistry - A European Journal. - : Wiley. - 1521-3765 .- 0947-6539. ; 25:70, s. 15998-16001
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Tidskriftsartikel (refereegranskat)abstract
- Continuous flow systems for chemical synthesis are becoming a major focus in organic chemistry and there is a growing interest in the integration of biocatalysts due to their high regio- and stereoselectivity. Methods established for 3D bioprinting enable the fast and simple production of agarose-based modules for biocatalytic reactors if thermally stable enzymes are available. We report here on the characterization of four different cofactor-free phenacrylate decarboxylase enzymes suitable for the production of 4-vinylphenol and test their applicability for the encapsulation and direct 3D printing of disk-shaped agarose-based modules that can be used for compartmentalized flow microreactors. Using the most active and stable phenacrylate decarboxylase from Enterobacter spec. in a setup with four parallel reactors and a subsequent palladium(II) acetate-catalysed Heck reaction, 4-hydroxystilbene was synthesized from p-coumaric acid with a total yield of 14.7 % on a milligram scale. We believe that, due to the convenient direct immobilization of any thermostable enzyme and straightforward tuning of the reaction sequence by stacking of modules with different catalytic activities, this simple process will facilitate the establishment and use of cascade reactions and will therefore be of great advantage for many research approaches.
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| 3. |
- Berglund, Anna-Karin, 1979, et al.
(författare)
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Nucleotide pools dictate the identity and frequency of ribonucleotide incorporation in mitochondrial DNA. : Mapping ribonucleotides in mitochondrial DNA
- 2017
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Ingår i: PLoS genetics. - : Public Library of Science (PLoS). - 1553-7404 .- 1553-7390. ; 13:2
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Tidskriftsartikel (refereegranskat)abstract
- Previous work has demonstrated the presence of ribonucleotides in human mitochondrial DNA (mtDNA) and in the present study we use a genome-wide approach to precisely map the location of these. We find that ribonucleotides are distributed evenly between the heavy- and light-strand of mtDNA. The relative levels of incorporated ribonucleotides reflect that DNA polymerase γ discriminates the four ribonucleotides differentially during DNA synthesis. The observed pattern is also dependent on the mitochondrial deoxyribonucleotide (dNTP) pools and disease-causing mutations that change these pools alter both the absolute and relative levels of incorporated ribonucleotides. Our analyses strongly suggest that DNA polymerase γ-dependent incorporation is the main source of ribonucleotides in mtDNA and argues against the existence of a mitochondrial ribonucleotide excision repair pathway in human cells. Furthermore, we clearly demonstrate that when dNTP pools are limiting, ribonucleotides serve as a source of building blocks to maintain DNA replication. Increased levels of embedded ribonucleotides in patient cells with disturbed nucleotide pools may contribute to a pathogenic mechanism that affects mtDNA stability and impair new rounds of mtDNA replication.
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| 4. |
- Engqvist, Martin, 1983, et al.
(författare)
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ANT: Software for Generating and Evaluating Degenerate Codons for Natural and Expanded Genetic Codes
- 2015
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Ingår i: ACS Synthetic Biology. - : American Chemical Society (ACS). - 2161-5063. ; 4:8, s. 935-938
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Tidskriftsartikel (refereegranskat)abstract
- The Ambiguous Nucleotide Tool (ANT) is a desktop application that generates and evaluates degenerate codons. Degenerate codons are used to represent DNA positions that have multiple possible nucleotide alternatives. This is useful for protein engineering and directed evolution, where primers specified with degenerate codons are used as a basis for generating libraries of protein sequences. ANT is intuitive and can be used in a graphical user interface or by interacting with the code through a defined application programming interface. ANT comes with full support for nonstandard, user-defined, or expanded genetic codes (translation tables), which is important because synthetic biology is being applied to an ever widening range of natural and engineered organisms. The Python source code for ANT is freely distributed so that it may be used without restriction, modified, and incorporated in other software or custom data pipelines.
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| 5. |
- Engqvist, Martin, 1983, et al.
(författare)
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Applications of protein engineering and directed evolution in plant research
- 2019
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Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 1532-2548 .- 0032-0889. ; 179:3, s. 907-917
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Tidskriftsartikel (refereegranskat)abstract
- Protein engineering and directed evolution are powerful technologies for probing protein sequencefunction relationships. Thesemethods have been used to engineer both plant-derived proteins and exogenous proteins heterologously expressed in plants. In this review, we aim to further increase the interdisciplinary crossover between the disciplines of protein engineering and plant biology by first introducing protein engineering in some detail. This introduction is key to understanding current limitations to protein engineering when applied to plants. Subsequently, we provide an overview of the recent methodological progress in, and novel applications of, protein engineering and directed evolution in plant research.
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| 6. |
- Engqvist, Martin, 1983
(författare)
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Correlating enzyme annotations with a large set of microbial growth temperatures reveals metabolic adaptations to growth at diverse temperatures
- 2018
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Ingår i: BMC Microbiology. - : Springer Science and Business Media LLC. - 1471-2180. ; 18:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: The ambient temperature of all habitats is a key physical property that shapes the biology of microbes inhabiting them. The optimal growth temperature (OGT) of a microbe, is therefore a key piece of data needed to understand evolutionary adaptations manifested in their genome sequence. Unfortunately there is no growth temperature database or easily downloadable dataset encompassing the majority of cultured microorganisms. We are thus limited in interpreting genomic data to identify temperature adaptations in microbes. Results: In this work I significantly contribute to closing this gap by mining data from major culture collection centres to obtain growth temperature data for a nonredundant set of 21,498 microbes. The dataset (https://doi.org/10.5281/zenodo.1175608) contains mainly bacteria and archaea and spans psychrophiles, mesophiles, thermophiles and hyperthermophiles. Using this data a full 43% of all protein entries in the UniProt database can be annotated with the growth temperature of the species from which they originate. I validate the dataset by showing a Pearson correlation of up to 0.89 between growth temperature and mean enzyme optima, a physiological property directly influenced by the growth temperature. Using the temperature dataset I correlate the genomic occurance of enzyme functional annotations with growth temperature. I identify 319 enzyme functions that either increase or decrease in occurrence with temperature. Eight metabolic pathways were statistically enriched for these enzyme functions. Furthermore, I establish a correlation between 33 domains of unknown function (DUFs) with growth temperature in microbes, four of which (DUF438, DUF1524, DUF1957 and DUF3458-C) were significant in both archaea and bacteria. Conclusions: The growth temperature dataset enables large-scale correlation analysis with enzyme function- and domain-level annotations. Growth-temperature dependent changes in their occurrence highlight potential evolutionary adaptations. A few of the identified changes are previously known, such as the preference for menaquinone biosynthesis through the futalosine pathway in bacteria growing at high temperatures. Others represent important starting points for future studies, such as DUFs where their occurrence change with temperature. The growth temperature dataset should become a valuable community resource and will find additional, important, uses in correlating genomic, transcriptomic, proteomic, metabolomic, phenotypic or taxonomic properties with temperature in future studies.
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| 7. |
- Engqvist, Martin, 1983, et al.
(författare)
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Directed evolution of gloeobacter violaceus rhodopsin spectral properties
- 2015
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Ingår i: Journal of Molecular Biology. - : Elsevier BV. - 0022-2836 .- 1089-8638. ; 427:1, s. 205-220
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Tidskriftsartikel (refereegranskat)abstract
- Proton-pumping rhodopsins (PPRs) are photoactive retinal-binding proteins that transport ions across biological membranes in response to light. These proteins are interesting for light-harvesting applications in bioenergy production, in optogenetics applications in neuroscience, and as fluorescent sensors of membrane potential. Little is known, however, about how the protein sequence determines the considerable variation in spectral properties of PPRs from different biological niches or how to engineer these properties in a given PPR. Here we report a comprehensive study of amino acid substitutions in the retinal-binding pocket of Gloeobacter violaceus rhodopsin (GR) that tune its spectral properties. Directed evolution generated 70 GR variants with absorption maxima shifted by up to ± 80 nm, extending the protein's light absorption significantly beyond the range of known natural PPRs. While proton-pumping activity was disrupted in many of the spectrally shifted variants, we identified single tuning mutations that incurred blue and red shifts of 42 nm and 22 nm, respectively, that did not disrupt proton pumping. Blue-shifting mutations were distributed evenly along the retinal molecule while red-shifting mutations were clustered near the residue K257, which forms a covalent bond with retinal through a Schiff base linkage. Thirty eight of the identified tuning mutations are not found in known microbial rhodopsins. We discovered a subset of red-shifted GRs that exhibit high levels of fluorescence relative to the WT (wild-type) protein.
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| 8. |
- Engqvist, Martin, 1983, et al.
(författare)
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GLYCOLATE OXIDASE3, a Glycolate Oxidase Homolog of Yeast l-Lactate Cytochrome c Oxidoreductase, Supports l-Lactate Oxidation in Roots of Arabidopsis
- 2015
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Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 1532-2548 .- 0032-0889. ; 169:2, s. 1042-1061
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Tidskriftsartikel (refereegranskat)abstract
- In roots of Arabidopsis (Arabidopsis thaliana), L-lactate is generated by the reduction of pyruvate via L-lactate dehydrogenase, but this enzyme does not efficiently catalyze the reverse reaction. Here, we identify the Arabidopsis glycolate oxidase (GOX) paralogs GOX1, GOX2, and GOX3 as putative L-lactate-metabolizing enzymes based on their homology to CYB2, the L-lactate cytochrome c oxidoreductase from the yeast Saccharomyces cerevisiae. We found that GOX3 uses L-lactate with a similar efficiency to glycolate; in contrast, the photorespiratory isoforms GOX1 and GOX2, which share similar enzymatic properties, use glycolate with much higher efficiencies than L-lactate. The key factor making GOX3 more efficient with L-lactate than GOX1 and GOX2 is a 5- to 10-fold lower Km for the substrate. Consequently, only GOX3 can efficiently metabolize L-lactate at low intracellular concentrations. Isotope tracer experiments as well as substrate toxicity tests using GOX3 loss-offunction and overexpressor plants indicate that L-lactate is metabolized in vivo by GOX3. Moreover, GOX3 rescues the lethal growth phenotype of a yeast strain lacking CYB2, which cannot grow on L-lactate as a sole carbon source. GOX3 is predominantly present in roots and mature to aging leaves but is largely absent from young photosynthetic leaves, indicating that it plays a role predominantly in heterotrophic rather than autotrophic tissues, at least under standard growth conditions. In roots of plants grown under normoxic conditions, loss of function of GOX3 induces metabolic rearrangements that mirror wild-type responses under hypoxia. Thus, we identified GOX3 as the enzyme that metabolizes L-lactate to pyruvate in vivo and hypothesize that it may ensure the sustainment of low levels of L-lactate after its formation under normoxia.
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| 9. |
- Engqvist, Martin, 1983
(författare)
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Highlighting the need for systems-level experimental characterization of plant metabolic enzymes
- 2016
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Ingår i: Frontiers in Plant Science. - : Frontiers Media SA. - 1664-462X. ; 7:JULY2016
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Tidskriftsartikel (refereegranskat)abstract
- The biology of living organisms is determined by the action and interaction of a large number of individual gene products, each with specific functions. Discovering and annotating the function of gene products is key to our understanding of these organisms. Controlled experiments and bioinformatic predictions both contribute to functional gene annotation. For most species it is difficult to gain an overview of what portion of gene annotations are based on experiments and what portion represent predictions. Here, I survey the current state of experimental knowledge of enzymes and metabolism in Arabidopsis thaliana as well as eleven economically important crops and forestry trees-with a particular focus on reactions involving organic acids in central metabolism. I illustrate the limited availability of experimental data for functional annotation of enzymes in most of these species. Many enzymes involved in metabolism of citrate, malate, fumarate, lactate, and glycolate in crops and forestry trees have not been characterized. Furthermore, enzymes involved in key biosynthetic pathways which shape important traits in crops and forestry trees have not been characterized. I argue for the development of novel high-throughput platforms with which limited functional characterization of gene products can be performed quickly and relatively cheaply. I refer to this approach as systems-level experimental characterization. The data collected from such platforms would form a layer intermediate between bioinformatic gene function predictions and in-depth experimental studies of these functions. Such a data layer would greatly aid in the pursuit of understanding a multiplicity of biological processes in living organisms.
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| 10. |
- Engqvist, Martin, 1983, et al.
(författare)
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Metabolic engineering of photorespiration
- 2017
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Ingår i: Methods in Molecular Biology. - New York, NY : Springer New York. - 1940-6029 .- 1064-3745. ; 1653, s. 137-155
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The introduction of two alternative glycolate catabolic pathways in the chloroplasts of Arabidopsis thaliana rendered plants with increased biomass. To introduce these synthetic pathways, the selected genes were stepwise integrated in the nuclear genome of wild-type plants. These plants were transformed by Agrobacterium tumefaciens carrying the binary vectors using the floral dip method. Selection of transformants was conducted using different selection agents and the expression of the transgenes was confirmed by PCR and enzyme activity measurements.
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