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1.
Nucleic Acids Res ; 51(D1): D1558-D1567, 2023 01 06.
Article in English | MEDLINE | ID: mdl-36420904

ABSTRACT

The SEVA platform (https://seva-plasmids.com) was launched one decade ago, both as a database (DB) and as a physical repository of plasmid vectors for genetic analysis and engineering of Gram-negative bacteria with a structure and nomenclature that follows a strict, fixed architecture of functional DNA segments. While the current update keeps the basic features of earlier versions, the platform has been upgraded not only with many more ready-to-use plasmids but also with features that expand the range of target species, harmonize DNA assembly methods and enable new applications. In particular, SEVA 4.0 includes (i) a sub-collection of plasmids for easing the composition of multiple DNA segments with MoClo/Golden Gate technology, (ii) vectors for Gram-positive bacteria and yeast and [iii] off-the-shelf constructs with built-in functionalities. A growing collection of plasmids that capture part of the standard-but not its entirety-has been compiled also into the DB and repository as a separate corpus (SEVAsib) because of its value as a resource for constructing and deploying phenotypes of interest. Maintenance and curation of the DB were accompanied by dedicated diffusion and communication channels that make the SEVA platform a popular resource for genetic analyses, genome editing and bioengineering of a large number of microorganisms.


Subject(s)
Bacteria , Databases, Factual , Bacteria/genetics , Cloning, Molecular , DNA , Genetic Vectors , Phenotype , Plasmids/genetics
2.
BMC Genomics ; 25(1): 649, 2024 Jun 28.
Article in English | MEDLINE | ID: mdl-38943073

ABSTRACT

Despite the fact that introns mean an energy and time burden for eukaryotic cells, they play an irreplaceable role in the diversification and regulation of protein production. As a common feature of eukaryotic genomes, it has been reported that in protein-coding genes, the longest intron is usually one of the first introns. The goal of our work was to find a possible difference in the biological function of genes that fulfill this common feature compared to genes that do not. Data on the lengths of all introns in genes were extracted from the genomes of six vertebrates (human, mouse, koala, chicken, zebrafish and fugu) and two other model organisms (nematode worm and arabidopsis). We showed that more than 40% of protein-coding genes have the relative position of the longest intron located in the second or third tertile of all introns. Genes divided according to the relative position of the longest intron were found to be significantly increased in different KEGG pathways. Genes with the longest intron in the first tertile predominate in a range of pathways for amino acid and lipid metabolism, various signaling, cell junctions or ABC transporters. Genes with the longest intron in the second or third tertile show increased representation in pathways associated with the formation and function of the spliceosome and ribosomes. In the two groups of genes defined in this way, we further demonstrated the difference in the length of the longest introns and the distribution of their absolute positions. We also pointed out other characteristics, namely the positive correlation between the length of the longest intron and the sum of the lengths of all other introns in the gene and the preservation of the exact same absolute and relative position of the longest intron between orthologous genes.


Subject(s)
Introns , Introns/genetics , Animals , Humans , Arabidopsis/genetics , Spliceosomes/genetics , Spliceosomes/metabolism
3.
Klin Padiatr ; 2024 Feb 06.
Article in English | MEDLINE | ID: mdl-38320582

ABSTRACT

BACKGROUND: Several previous studies have reported a more severe course of nephrotic syndrome in children with low birth weight. PATIENTS: Cohort of 223 children with idiopathic nephrotic syndrome. METHODS: We aimed to investigate the association between course of nephrotic syndrome and low birth weight. Data from seven paediatric nephrology centres were used. RESULTS: Children with low birth weight had 3.84 times higher odds for a more severe course of steroid-sensitive nephrotic syndrome (95% CI 1.20-17.22, P=0.041), and those with low birth weight and remission after 7 days had much higher odds for a more severe course of disease (OR 8.7). Low birth weight children had a longer time to remission (median 12 vs. 10 days, P=0.03). They had a higher need for steroid-sparing agents (OR for the same sex=3.26 [95% CI 1.17-11.62, P=0.039]), and the odds were even higher in females with low birth weight (OR 6.81). There was no evidence of an association either between low birth weight and focal segmental glomerulosclerosis or between low birth weight and steroid-resistant nephrotic syndrome. DISCUSSION: We conducted the first multicentric study confirming the worse outcomes of children with NS and LBW and we found additional risk factors. CONCLUSIONS: Low birth weight is associated with a more severe course of steroid-sensitive nephrotic syndrome, while being female and achieving remission after 7 days are additional risk factors.

4.
Environ Microbiol ; 25(5): 1041-1054, 2023 05.
Article in English | MEDLINE | ID: mdl-36683138

ABSTRACT

The biodegradative capacity of bacteria in their natural habitats is affected by water availability. In this work, we have examined the activity and effector specificity of the transcriptional regulator XylR of the TOL plasmid pWW0 of Pseudomonas putida mt-2 for biodegradation of m-xylene when external water potential was manipulated with polyethylene glycol PEG8000. By using non-disruptive luxCDEAB reporter technology, we noticed that the promoter activated by XylR (Pu) restricted its activity and the regulator became more effector-specific towards head TOL substrates when cells were grown under water subsaturation. Such a tight specificity brought about by water limitation was relaxed when intracellular osmotic stress was counteracted by the external addition of the compatible solute glycine betaine. With these facts in hand, XylR variants isolated earlier as effector-specificity responders to the non-substrate 1,2,4-trichlorobenzene under high matric stress were re-examined and found to be unaffected by water potential in vivo. All these phenomena could be ultimately explained as the result of water potential-dependent conformational changes in the A domain of XylR and its effector-binding pocket, as suggested by AlphaFold prediction of protein structures. The consequences of this scenario for the evolution of specificities in regulators and the emergence of catabolic pathways are discussed.


Subject(s)
Pseudomonas putida , Transcription Factors , Transcription Factors/genetics , Transcription Factors/metabolism , DNA-Binding Proteins/metabolism , Pseudomonas putida/genetics , Pseudomonas putida/metabolism , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Promoter Regions, Genetic , Xylenes/metabolism , Plasmids , Gene Expression Regulation, Bacterial
5.
Metab Eng ; 75: 29-46, 2023 01.
Article in English | MEDLINE | ID: mdl-36343876

ABSTRACT

Pseudomonas putida KT2440 is an attractive bacterial host for biotechnological production of valuable chemicals from renewable lignocellulosic feedstocks as it can valorize lignin-derived aromatics or glucose obtainable from cellulose. P. putida EM42, a genome-reduced variant of strain KT2440 endowed with advantageous physiological properties, was recently engineered for growth on cellobiose, a major cellooligosaccharide product of enzymatic cellulose hydrolysis. Co-utilization of cellobiose and glucose was achieved in a mutant lacking periplasmic glucose dehydrogenase Gcd (PP_1444). However, the cause of the co-utilization phenotype remained to be understood and the Δgcd strain had a significant growth defect. In this study, we investigated the basis of the simultaneous uptake of the two sugars and accelerated the growth of P. putida EM42 Δgcd mutant for the bioproduction of valuable compounds from glucose and cellobiose. We show that the gcd deletion lifted the inhibition of the exogenous ß-glucosidase BglC from Thermobifida fusca exerted by the intermediates of the periplasmic glucose oxidation pathway. The additional deletion of hexR gene, which encodes a repressor of the upper glycolysis genes, failed to restore rapid growth on glucose. The reduced growth rate of the Δgcd mutant was partially compensated by the implantation of heterologous glucose and cellobiose transporters (Glf from Zymomonas mobilis and LacY from Escherichia coli, respectively). Remarkably, this intervention resulted in the accumulation of pyruvate in aerobic P. putida cultures. We demonstrated that the excess of this key metabolic intermediate can be redirected to the enhanced biosynthesis of ethanol and lactate. The pyruvate overproduction phenotype was then unveiled by an upgraded genome-scale metabolic model constrained with proteomic and kinetic data. The model pointed to the saturation of glucose catabolism enzymes due to unregulated substrate uptake and it predicted improved bioproduction of pyruvate-derived chemicals by the engineered strain. This work sheds light on the co-metabolism of cellulosic sugars in an attractive biotechnological host and introduces a novel strategy for pyruvate overproduction in bacterial cultures under aerobic conditions.


Subject(s)
Escherichia coli Proteins , Pseudomonas putida , Symporters , Pseudomonas putida/genetics , Pseudomonas putida/metabolism , Cellobiose/metabolism , Glucose/metabolism , Pyruvic Acid/metabolism , Proteomics , Cellulose/metabolism , Escherichia coli/metabolism , Metabolic Engineering , Monosaccharide Transport Proteins/genetics , Monosaccharide Transport Proteins/metabolism , Symporters/metabolism , Escherichia coli Proteins/genetics
6.
Cancer Cell Int ; 23(1): 295, 2023 Nov 26.
Article in English | MEDLINE | ID: mdl-38008721

ABSTRACT

BACKGROUND: Colorectal cancer is a highly prevalent and deadly. The most common metastatic site is the liver. We performed a whole exome sequencing analysis of a series of metachronous colorectal cancer liver metastases (mCLM) and matched non-malignant liver tissues to investigate the genomic profile of mCLM and explore associations with the patients' prognosis and therapeutic modalities. METHODS: DNA samples from mCLM and non-malignant liver tissue pairs (n = 41) were sequenced using whole exome target enrichment and their germline and somatic genetic variability, copy number variations, and mutational signatures were assessed for associations with relapse-free (RFS) and overall survival (OS). RESULTS: Our genetic analysis could stratify all patients into existing targeted therapeutic regimens. The most commonly mutated genes in mCLM were TP53, APC, and KRAS together with PIK3CA and several passenger genes like ABCA13, FAT4, PCLO, and UNC80. Patients with somatic alterations in genes from homologous recombination repair, Notch, and Hedgehog pathways had significantly prolonged RFS, while those with altered MYC pathway genes had poor RFS. Additionally, alterations in the JAK-STAT pathway were prognostic of longer OS. Patients bearing somatic variants in VIPR2 had significantly shorter OS and those with alterations in MUC16 prolonged OS. Carriage of the KRAS-12D variant was associated with shortened survival in our and external datasets. On the other hand, tumor mutation burden, mismatch repair deficiency, microsatellite instability, mutational signatures, or copy number variation in mCLM had no prognostic value. CONCLUSIONS: The results encourage further molecular profiling for personalized treatment of colorectal cancer liver metastases discerning metachronous from synchronous scenarios.

7.
Int J Mol Sci ; 24(10)2023 May 17.
Article in English | MEDLINE | ID: mdl-37240218

ABSTRACT

DNA repair pathways are essential for maintaining genome stability, and understanding the regulation of these mechanisms may help in the design of new strategies for treatments, the prevention of platinum-based chemoresistance, and the prolongation of overall patient survival not only with respect to ovarian cancer. The role of hyperthermic intraperitoneal chemotherapy (HIPEC) together with cytoreductive surgery (CRS) and adjuvant systemic chemotherapy is receiving more interest in ovarian cancer (OC) treatment because of the typical peritoneal spread of the disease. The aim of our study was to compare the expression level of 84 genes involved in the DNA repair pathway in tumors and the paired peritoneal metastasis tissue of patients treated with CRS/platinum-based HIPEC with respect to overall patient survival, presence of peritoneal carcinomatosis, treatment response, and alterations in the BRCA1 and BRCA2 genes. Tumors and metastatic tissue from 28 ovarian cancer patients collected during cytoreductive surgery before HIPEC with cisplatin were used for RNA isolation and subsequent cDNA synthesis. Quantitative real-time PCR followed. The most interesting findings of our study are undoubtedly the gene interactions among the genes CCNH, XPA, SLK, RAD51C, XPA, NEIL1, and ATR for primary tumor tissue and ATM, ATR, BRCA2, CDK7, MSH2, MUTYH, POLB, and XRCC4 for metastases. Another interesting finding is the correlation between gene expression and overall survival (OS), where a low expression correlates with a worse OS.


Subject(s)
DNA Glycosylases , Hyperthermia, Induced , Ovarian Neoplasms , Humans , Female , Hyperthermic Intraperitoneal Chemotherapy , Disease-Free Survival , Hyperthermia, Induced/methods , Ovarian Neoplasms/drug therapy , Ovarian Neoplasms/genetics , DNA Repair/genetics , Combined Modality Therapy , Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Survival Rate , Retrospective Studies , DNA Glycosylases/genetics
8.
Int J Gynecol Cancer ; 2022 Sep 13.
Article in English | MEDLINE | ID: mdl-36100282

ABSTRACT

BACKGROUND: The role of adjuvant treatment in the intermediate-risk group of patients with early-stage cervical cancer is controversial and is supported by a single randomized Gynecologic Oncology Group (GOG) 92 study performed more than 20 years ago. Recent retrospective studies have shown excellent local control in this group of patients after radical surgery with no additional adjuvant treatment. PRIMARY OBJECTIVE: To evaluate if adjuvant (chemo)radiation is associated with a survival benefit after radical surgery in patients with intermediate-risk cervical cancer. STUDY HYPOTHESIS: Radical surgery alone is non-inferior to the combined treatment of radical surgery followed by adjuvant (chemo)radiation in disease-free survival in patients with intermediate-risk cervical cancer. TRIAL DESIGN: This is a phase III, international, multicenter, randomized, non-inferiority trial in which patients with intermediate-risk cervical cancer will be randomized 1:1 into arm A, with no additional treatment after radical surgery, and arm B, receiving adjuvant external beam radiotherapy±brachytherapy ± concomitant chemotherapy. Patient data will be collected over 3 years post-randomization of the last enrolled patient for primary endpoint analysis or for 6 years for the overall survival analysis. MAJOR INCLUSION/EXCLUSION CRITERIA: Patients with intermediate-risk early-stage cervical cancer (IB1-IIA), defined as lymph node-negative patients with a combination of negative prognostic factors (tumor size >4 cm; tumor size >2 cm and lymphovascular space invasion; deep stromal invasion >2/3; or tumor-free distance <3 mm) with squamous cell carcinoma or human papillomavirus (HPV)-related adenocarcinoma, are eligible for the trial. PRIMARY ENDPOINT: Disease-free survival defined as time from randomization to recurrence diagnosis. SAMPLE SIZE: 514 patients from up to 90 sites will be randomized. ESTIMATED DATES FOR COMPLETING ACCRUAL AND PRESENTING RESULTS: It is estimated that the accrual will be completed by 2027 (with 3 additional years of follow-up) and primary endpoint results will be published by 2031. Estimated trial completion is by 2034. TRIAL REGISTRATION: NCT04989647.

9.
Environ Microbiol ; 23(8): 4418-4433, 2021 08.
Article in English | MEDLINE | ID: mdl-34097798

ABSTRACT

A revised model of the aromatic binding A domain of the σ54 -dependent regulator XylR of Pseudomonas putida mt-2 was produced based on the known 3D structures of homologous regulators PoxR, MopR and DmpR. The resulting frame was instrumental for mapping a number of mutations known to alter effector specificity, which were then reinterpreted under a dependable spatial reference. Some of these changes involved the predicted aromatic binding pocket but others occurred in distant locations, including dimerization interfaces and putative zinc binding site. The effector pocket was buried within the protein structure and accessible from the outside only through a narrow tunnel. Yet, several loop regions of the A domain could provide the flexibility required for widening such a tunnel for passage of aromatic ligands. The model was experimentally validated by treating the cells in vivo and the purified protein in vitro with benzyl bromide, which reacts with accessible nucleophilic residues on the protein surface. Structural and proteomic analyses confirmed the predicted in/out distribution of residues but also supported two additional possible scenarios of interaction of the A domain with aromatic effectors: a dynamic interaction of the fully structured yet flexible protein with the aromatic partner and/or inducer-assisted folding of the A domain.


Subject(s)
Pseudomonas putida , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , DNA-Binding Proteins/metabolism , Gene Expression Regulation, Bacterial , Models, Structural , Plasmids , Proteomics , Pseudomonas putida/genetics , Pseudomonas putida/metabolism , Transcription Factors/genetics
10.
Int J Mol Sci ; 21(22)2020 Nov 23.
Article in English | MEDLINE | ID: mdl-33238634

ABSTRACT

The 12 members of the ABCA subfamily in humans are known for their ability to transport cholesterol and its derivatives, vitamins, and xenobiotics across biomembranes. Several ABCA genes are causatively linked to inborn diseases, and the role in cancer progression and metastasis is studied intensively. The regulation of translation initiation is implicated as the major mechanism in the processes of post-transcriptional modifications determining final protein levels. In the current bioinformatics study, we mapped the features of the 5' untranslated regions (5'UTR) known to have the potential to regulate translation, such as the length of 5'UTRs, upstream ATG codons, upstream open-reading frames, introns, RNA G-quadruplex-forming sequences, stem loops, and Kozak consensus motifs, in the DNA sequences of all members of the subfamily. Subsequently, the conservation of the features, correlations among them, ribosome profiling data as well as protein levels in normal human tissues were examined. The 5'UTRs of ABCA genes contain above-average numbers of upstream ATGs, open-reading frames and introns, as well as conserved ones, and these elements probably play important biological roles in this subfamily, unlike RG4s. Although we found significant correlations among the features, we did not find any correlation between the numbers of 5'UTR features and protein tissue distribution and expression scores. We showed the existence of single nucleotide variants in relation to the 5'UTR features experimentally in a cohort of 105 breast cancer patients. 5'UTR features presumably prepare a complex playground, in which the other elements such as RNA binding proteins and non-coding RNAs play the major role in the fine-tuning of protein expression.


Subject(s)
ATP Binding Cassette Transporter, Subfamily A/genetics , Biological Transport/genetics , Multigene Family/genetics , Ribosomes/genetics , 5' Untranslated Regions/genetics , ATP Binding Cassette Transporter, Subfamily A/classification , ATP Binding Cassette Transporter, Subfamily A/metabolism , Cholesterol/metabolism , Computational Biology , Humans , Introns/genetics , Open Reading Frames/genetics , Polymorphism, Single Nucleotide/genetics , Protein Biosynthesis/genetics , Ribosomes/metabolism , Xenobiotics/metabolism
11.
Metab Eng ; 48: 94-108, 2018 07.
Article in English | MEDLINE | ID: mdl-29864584

ABSTRACT

Given its capacity to tolerate stress, NAD(P)H/ NAD(P) balance, and increased ATP levels, the platform strain Pseudomonas putida EM42, a genome-edited derivative of the soil bacterium P. putida KT2440, can efficiently host a suite of harsh reactions of biotechnological interest. Because of the lifestyle of the original isolate, however, the nutritional repertoire of P. putida EM42 is centered largely on organic acids, aromatic compounds and some hexoses (glucose and fructose). To enlarge the biochemical network of P. putida EM42 to include disaccharides and pentoses, we implanted heterologous genetic modules for D-cellobiose and D-xylose metabolism into the enzymatic complement of this strain. Cellobiose was actively transported into the cells through the ABC complex formed by native proteins PP1015-PP1018. The knocked-in ß-glucosidase BglC from Thermobifida fusca catalyzed intracellular cleavage of the disaccharide to D-glucose, which was then channelled to the default central metabolism. Xylose oxidation to the dead end product D-xylonate was prevented by deleting the gcd gene that encodes the broad substrate range quinone-dependent glucose dehydrogenase. Intracellular intake was then engineered by expressing the Escherichia coli proton-coupled symporter XylE. The sugar was further metabolized by the products of E. coli xylA (xylose isomerase) and xylB (xylulokinase) towards the pentose phosphate pathway. The resulting P. putida strain co-utilized xylose with glucose or cellobiose to complete depletion of the sugars. These results not only show the broadening of the metabolic capacity of a soil bacterium towards new substrates, but also promote P. putida EM42 as a platform for plug-in of new biochemical pathways for utilization and valorization of carbohydrate mixtures from lignocellulose processing.


Subject(s)
Cellobiose/metabolism , Glucose/metabolism , Pseudomonas putida , Xylose/metabolism , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Cellobiose/genetics , Gene Knock-In Techniques , Glucose/genetics , Oxidation-Reduction , Pseudomonas putida/genetics , Pseudomonas putida/metabolism , Xylose/genetics , beta-Glucosidase/genetics , beta-Glucosidase/metabolism
12.
Biotechnol Bioeng ; 115(4): 850-862, 2018 04.
Article in English | MEDLINE | ID: mdl-29278409

ABSTRACT

Fibroblast growth factors (FGFs) serve numerous regulatory functions in complex organisms, and their corresponding therapeutic potential is of growing interest to academics and industrial researchers alike. However, applications of these proteins are limited due to their low stability. Here we tackle this problem using a generalizable computer-assisted protein engineering strategy to create a unique modified FGF2 with nine mutations displaying unprecedented stability and uncompromised biological function. The data from the characterization of stabilized FGF2 showed a remarkable prediction potential of in silico methods and provided insight into the unfolding mechanism of the protein. The molecule holds a considerable promise for stem cell research and medical or pharmaceutical applications.


Subject(s)
Computer-Aided Design , Fibroblast Growth Factor 2/genetics , Fibroblast Growth Factor 2/metabolism , Protein Engineering , Protein Stability , Amino Acid Sequence , Animals , Computer Simulation , Directed Molecular Evolution , Embryonic Stem Cells/cytology , Embryonic Stem Cells/metabolism , Fibroblast Growth Factor 2/chemistry , Humans , Point Mutation , Protein Folding
13.
Tumour Biol ; 39(5): 1010428317699800, 2017 May.
Article in English | MEDLINE | ID: mdl-28468577

ABSTRACT

Adenosine triphosphate-binding cassette proteins constitute a large family of active transporters through extracellular and intracellular membranes. Increased drug efflux based on adenosine triphosphate-binding cassette protein activity is related to the development of cancer cell chemoresistance. Several articles have focused on adenosine triphosphate-binding cassette gene expression profiles (signatures), based on the expression of all 49 human adenosine triphosphate-binding cassette genes, in individual tumor types and reported connections to established clinicopathological features. The aim of this study was to test our theory about the existence of adenosine triphosphate-binding cassette gene expression profiles common to multiple types of tumors, which may modify tumor progression and provide clinically relevant information. Such general adenosine triphosphate-binding cassette profiles could constitute a new attribute of carcinogenesis. Our combined cohort consisted of tissues from 151 cancer patients-breast, colorectal, and pancreatic carcinomas. Standard protocols for RNA isolation and quantitative real-time polymerase chain reaction were followed. Gene expression data from individual tumor types as well as a merged tumor dataset were analyzed by bioinformatics tools. Several general adenosine triphosphate-binding cassette profiles, with differences in gene functions, were established and shown to have significant relations to clinicopathological features such as tumor size, histological grade, or clinical stage. Genes ABCC7, A3, A8, A12, and C8 prevailed among the most upregulated or downregulated ones. In conclusion, the results supported our theory about general adenosine triphosphate-binding cassette gene expression profiles and their importance for cancer on clinical as well as research levels. The presence of ABCC7 (official symbol CFTR) among the genes with key roles in the profiles supports the emerging evidence about its crucial role in various cancers. Graphical abstract.


Subject(s)
ATP-Binding Cassette Transporters/biosynthesis , Carcinogenesis , Cystic Fibrosis Transmembrane Conductance Regulator/biosynthesis , Sulfonylurea Receptors/biosynthesis , ATP-Binding Cassette Transporters/genetics , Breast Neoplasms/genetics , Breast Neoplasms/pathology , Colorectal Neoplasms/genetics , Colorectal Neoplasms/pathology , Cystic Fibrosis Transmembrane Conductance Regulator/genetics , Female , Gene Expression Regulation, Neoplastic , Humans , Pancreatic Neoplasms/genetics , Pancreatic Neoplasms/pathology , Sulfonylurea Receptors/genetics , Transcriptome/genetics , Pancreatic Neoplasms
14.
Photochem Photobiol Sci ; 16(12): 1757-1761, 2017 Dec 06.
Article in English | MEDLINE | ID: mdl-29170770

ABSTRACT

The quantum yields of azobenzene photoisomerization in methanol solution were redetermined using newly obtained molar absorption coefficients of its cis- and trans-isomers. The results differ substantially from those published previously, especially in the range of the nπ* absorption band. Besides actinometry, these findings are relevant for applications of azobenzene derivatives in optical switching.

15.
Photochem Photobiol Sci ; 16(12): 1749-1756, 2017 Dec 06.
Article in English | MEDLINE | ID: mdl-29170780

ABSTRACT

Azobenzene is a prototypical photochromic molecule existing in two isomeric forms, which has numerous photochemical applications that rely on a precise knowledge of the molar absorption coefficients (ε). Careful analysis revealed that the previously reported absorption spectra of the "pure" isomers were in fact mutually contaminated by small amounts of the other isomer. Therefore, the absorption spectra of both trans- and cis-azobenzene in methanol were re-determined at temperatures of 5-45 °C. The thermodynamically more stable trans-azobenzene was prepared by warming the solution in the dark. To obtain the spectrum of cis-azobenzene three methods were used, which gave consistent results within the limits of error. The method based on the subtraction of derivative spectra coupled with a global analysis of the spectra recorded during thermal cis-trans isomerization is shown to give slightly more reliable results than the method using isomeric ratios determined by 1H-NMR. The described methods are readily generalizable to other azobenzene derivatives and to other photochromic systems. The practical implication of the re-determined ε values is demonstrated by a very high precision of spectrophotometric species analysis in azobenzene isomeric mixtures. The new ε values imply that the previously reported quantum yields must be revised.

16.
Microb Cell Fact ; 14: 201, 2015 Dec 21.
Article in English | MEDLINE | ID: mdl-26691337

ABSTRACT

BACKGROUND: Heterologous expression systems based on promoters inducible with isopropyl-ß-D-1-thiogalactopyranoside (IPTG), e.g., Escherichia coli BL21(DE3) and cognate LacI(Q)/P(lacUV5)-T7 vectors, are commonly used for production of recombinant proteins and metabolic pathways. The applicability of such cell factories is limited by the complex physiological burden imposed by overexpression of the exogenous genes during a bioprocess. This burden originates from a combination of stresses that may include competition for the expression machinery, side-reactions due to the activity of the recombinant proteins, or the toxicity of their substrates, products and intermediates. However, the physiological impact of IPTG-induced conditional expression on the recombinant host under such harsh conditions is often overlooked. RESULTS: The physiological responses to IPTG of the E. coli BL21(DE3) strain and three different recombinants carrying a synthetic metabolic pathway for biodegradation of the toxic anthropogenic pollutant 1,2,3-trichloropropane (TCP) were investigated using plating, flow cytometry, and electron microscopy. Collected data revealed unexpected negative synergistic effect of inducer of the expression system and toxic substrate resulting in pronounced physiological stress. Replacing IPTG with the natural sugar effector lactose greatly reduced such stress, demonstrating that the effect was due to the original inducer's chemical properties. CONCLUSIONS: IPTG is not an innocuous inducer; instead, it exacerbates the toxicity of haloalkane substrate and causes appreciable damage to the E. coli BL21(DE3) host, which is already bearing a metabolic burden due to its content of plasmids carrying the genes of the synthetic metabolic pathway. The concentration of IPTG can be effectively tuned to mitigate this negative effect. Importantly, we show that induction with lactose, the natural inducer of P lac , dramatically lightens the burden without reducing the efficiency of the synthetic TCP degradation pathway. This suggests that lactose may be a better inducer than IPTG for the expression of heterologous pathways in E. coli BL21(DE3).


Subject(s)
Escherichia coli/metabolism , Isopropyl Thiogalactoside/adverse effects , Metabolic Networks and Pathways/genetics , Isopropyl Thiogalactoside/genetics , Metabolic Engineering
17.
Chembiochem ; 15(13): 1891-5, 2014 Sep 05.
Article in English | MEDLINE | ID: mdl-25099170

ABSTRACT

Multienzyme processes represent an important area of biocatalysis. Their efficiency can be enhanced by optimization of the stoichiometry of the biocatalysts. Here we present a workflow for maximizing the efficiency of a three-enzyme system catalyzing a five-step chemical conversion. Kinetic models of pathways with wild-type or engineered enzymes were built, and the enzyme stoichiometry of each pathway was optimized. Mathematical modeling and one-pot multienzyme experiments provided detailed insights into pathway dynamics, enabled the selection of a suitable engineered enzyme, and afforded high efficiency while minimizing biocatalyst loadings. Optimizing the stoichiometry in a pathway with an engineered enzyme reduced the total biocatalyst load by an impressive 56 %. Our new workflow represents a broadly applicable strategy for optimizing multienzyme processes.


Subject(s)
Biocatalysis , Enzymes/chemistry , Algorithms , Kinetics , Models, Chemical , Protein Engineering , Workflow
18.
Hematol Oncol ; 32(2): 82-6, 2014 Jun.
Article in English | MEDLINE | ID: mdl-23949951

ABSTRACT

The translocation t(2;11)(p21;q23) is associated with de novo myelodysplastic syndromes (MDS) and has an overall frequency of approximately 1%. The outcome of MDS patients with this translocation is not clear until now, because most of the clinical data addressing the t(2;11)(p21;q23) has been collected without investigating the status of the mixed lineage leukemia (MLL) gene. In this report, we present seven new patients with MDS diagnosis and the t(2;11)(p21;q23) in bone marrow cells; all of them without MLL gene rearrangement. They were found in two databases consisting of 1185 patients of two Czech institutions. These patients tended to be younger and showed a strong male predominance. A cytological and histological assessment of bone marrow at diagnosis revealed only mild MDS with marked dysplasia in megakaryopoiesis. Similar to other primary abnormalities in MDS (e.g. deletion of 11q), the t(2;11)(p21;q23) was frequently associated with deletion of 5q. Our results stress the common clinicopathological features of this entity and indicate that the t(2;11)(p21;q23) may be associated with a good prognosis for MDS patients (median survival 72 months).


Subject(s)
Chromosomes, Human, Pair 11 , Chromosomes, Human, Pair 2 , Myelodysplastic Syndromes/genetics , Myeloid-Lymphoid Leukemia Protein/genetics , Translocation, Genetic , Adult , Aged , Gene Rearrangement , Histone-Lysine N-Methyltransferase , Humans , Male , Middle Aged , Myelodysplastic Syndromes/pathology , Prognosis
19.
Environ Sci Technol ; 48(12): 6859-66, 2014 Jun 17.
Article in English | MEDLINE | ID: mdl-24787668

ABSTRACT

The anthropogenic compound 1,2,3-trichloropropane (TCP) has recently drawn attention as an emerging groundwater contaminant. No living organism, natural or engineered, is capable of the efficient aerobic utilization of this toxic industrial waste product. We describe a novel biotechnology for transforming TCP based on an immobilized synthetic pathway. The pathway is composed of three enzymes from two different microorganisms: engineered haloalkane dehalogenase from Rhodococcus rhodochrous NCIMB 13064, and haloalcohol dehalogenase and epoxide hydrolase from Agrobacterium radiobacter AD1. Together, they catalyze consecutive reactions converting toxic TCP to harmless glycerol. The pathway was immobilized in the form of purified enzymes or cell-free extracts, and its performance was tested in batch and continuous systems. Using a packed bed reactor filled with the immobilized biocatalysts, 52.6 mmol of TCP was continuously converted into glycerol within 2.5 months of operation. The efficiency of the TCP conversion to the intermediates was 97%, and the efficiency of conversion to the final product glycerol was 78% during the operational period. Immobilized biocatalysts are suitable for removing TCP from contaminated water up to a 10 mM solubility limit, which is an order of magnitude higher than the concentration tolerated by living microorganisms.


Subject(s)
Enzymes, Immobilized/metabolism , Metabolic Networks and Pathways , Propane/analogs & derivatives , Water Pollutants, Chemical/metabolism , Water Pollutants, Chemical/toxicity , Agrobacterium/enzymology , Biocatalysis/drug effects , Biodegradation, Environmental/drug effects , Bioreactors/microbiology , Biotransformation/drug effects , Hydrolases/metabolism , Metabolic Networks and Pathways/drug effects , Propane/chemistry , Propane/metabolism , Propane/toxicity , Rhodococcus/enzymology , Time Factors
20.
Bull Geosci ; 89(2): 245-256, 2014 Mar 24.
Article in English | MEDLINE | ID: mdl-25983568

ABSTRACT

Because of close morphological affinities, fossil cheliped fragments of the ghost shrimp Ctenocheles (Decapoda, Axiidea, Ctenochelidae) can be easily misidentified as remains of different decapod crustacean taxa. Re-examination of the Cretaceous decapods deposited in the National Museum in Prague revealed that all supposed specimens of the lobster genus Oncopareia found in the Middle Coniacian calcareous claystones of the Brezno Formation, including one of the Fritsch's original specimens of Stenocheles parvulus, actually belong to Ctenocheles. This material together with newly collected specimens from the same locality, allowed for erection of a new species, Ctenocheles fritschi. Its major chela possesses a serrated ischium and ovoid, unarmed merus; therefore, it is considered a close relative of the extant C. collini and C. maorianus. Ctenocheles fritschi sp. nov. represents the first report on the occurrence of the genus from the Bohemian Cretaceous Basin. It is one of the oldest records of Ctenocheles and simultaneously one of the best preserved fossils of the genus reported to date. Confusing taxonomy of S. parvulus is reviewed and shortly discussed.

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