scholarly journals Functional Expression of a DNA-Topoisomerase IB fromCryptosporidium parvum

2009 ◽  
Vol 2009 ◽  
pp. 1-9 ◽  
Author(s):  
César Ordóñez ◽  
Javier Alfonso ◽  
Rafael Balaña-Fouce ◽  
David Ordóñez
Keyword(s):  
Expression System ◽  
Functional Expression ◽  
Structural Features ◽  
Water Soluble ◽  
Irreversible Inhibitor ◽  
Dna Topoisomerase ◽  
Yeast Expression System ◽  
Topoisomerase Ib ◽  
Single Polypeptide

Cryptosporidium parvum, one of the most important causative organisms of human diarrheas during childhood, contains a monomeric DNA-topoisomerase IB (CpTopIB) in chromosome 7. Heterologous expression ofCpTopIBgene in a budding yeast strain lacking this activity proves that the cryptosporidial enzyme is functional in vivo. The enzymatic activity is comprised in a single polypeptide, which contains all the structural features defining a fully active TopIB. Relaxation activity of the yeast extracts was detected only whenCpTopIBORF was expressed in a yeast expression system showing time and protein dependence under steady state kinetic conditions. The susceptibility of CpTopIB-transformed yeast to the irreversible inhibitor camptothecin and its water-soluble derivatives (topotecan and SN-38) was assessed.

scholarly journals Activity of Indenoisoquinolines against African Trypanosomes

2008 ◽  
Vol 53 (1) ◽  
pp. 123-128 ◽  
Author(s):  
Rahul P. Bakshi ◽  
Dongpei Sang ◽  
Andrew Morrell ◽  
Mark Cushman ◽  
Theresa A. Shapiro
Keyword(s):  
Anticancer Agents ◽  
Mammalian Cells ◽  
Sleeping Sickness ◽  
Water Soluble ◽  
African Trypanosomes ◽  
In Vivo Experiments ◽  
Topoisomerase Ib ◽  
Topoisomerase Poisons

ABSTRACT African trypanosomiasis (sleeping sickness), caused by protozoan Trypanosoma brucei species, is a debilitating disease that is lethal if untreated. Available drugs are antiquated, toxic, and compromised by emerging resistance. The indenoisoquinolines are a class of noncamptothecin topoisomerase IB poisons that are under development as anticancer agents. We tested a variety of indenoisoquinolines for their ability to kill T. brucei. Indenoisoquinolines proved trypanocidal at submicromolar concentrations in vitro. Structure-activity analysis yielded motifs that enhanced potency, including alkylamino substitutions on N-6, methoxy groups on C-2 and C-3, and a methylenedioxy bridge between C-8 and C-9. Detailed analysis of eight water-soluble indenoisoquinolines demonstrated that in trypanosomes the compounds inhibited DNA synthesis and acted as topoisomerase poisons. Testing these compounds on L1210 mouse leukemia cells revealed that all eight were more effective against trypanosomes than against mammalian cells. In preliminary in vivo experiments one compound delayed parasitemia and extended survival in mice subjected to a lethal trypanosome challenge. The indenoisoquinolines provide a promising lead for the development of drugs against sleeping sickness.

scholarly journals Biosynthesis of Cyanobacterial Phycobiliproteins in Escherichia coli: Chromophorylation Efficiency and Specificity of All Bilin Lyases from Synechococcus sp. Strain PCC 7002

2010 ◽  
Vol 76 (9) ◽  
pp. 2729-2739 ◽  
Author(s):  
Avijit Biswas ◽  
Yasmin M. Vasquez ◽  
Tierna M. Dragomani ◽  
Monica L. Kronfel ◽  
Shervonda R. Williams ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Biosynthetic Pathway ◽  
Expression System ◽  
Water Soluble ◽  
Soluble Form ◽  
Beta Subunits ◽  
Lyase Activity ◽  
Synechococcus Sp ◽  
Tetrapyrrole Chromophores

ABSTRACT Phycobiliproteins are water-soluble, light-harvesting proteins that are highly fluorescent due to linear tetrapyrrole chromophores, which makes them valuable as probes. Enzymes called bilin lyases usually attach these bilin chromophores to specific cysteine residues within the alpha and beta subunits via thioether linkages. A multiplasmid coexpression system was used to recreate the biosynthetic pathway for phycobiliproteins from the cyanobacterium Synechococcus sp. strain PCC 7002 in Escherichia coli. This system efficiently produced chromophorylated allophycocyanin (ApcA/ApcB) and α-phycocyanin with holoprotein yields ranging from 3 to 12 mg liter−1 of culture. This heterologous expression system was used to demonstrate that the CpcS-I and CpcU proteins are both required to attach phycocyanobilin (PCB) to allophycocyanin subunits ApcD (αAP-B) and ApcF (β18). The N-terminal, allophycocyanin-like domain of ApcE (LCM 99) was produced in soluble form and was shown to have intrinsic bilin lyase activity. Lastly, this in vivo system was used to evaluate the efficiency of the bilin lyases for production of β-phycocyanin.

scholarly journals Chloroplast thioredoxin mutants without active-site cysteines facilitate the reduction of the regulatory disulphide bridge on the γ-subunit of chloroplast ATP synthase

1999 ◽  
Vol 341 (1) ◽  
pp. 157-163 ◽  
Author(s):  
Michael T. STUMPP ◽  
Ken MOTOHASHI ◽  
Toru HISABORI
Keyword(s):  
Active Site ◽  
High Efficiency ◽  
Expression System ◽  
Water Soluble ◽  
Subsequent Reduction ◽  
Disulphide Bridge ◽  
Mutant Proteins ◽  
Apparent Affinity ◽  
Γ Subunit

The activity of the chloroplast H+-ATPase (CFoCF1) is regulated by the proton electrochemical membrane potential and the reduction or the formation of the disulphide bridge on the γ-subunit mediated by chloroplast thioredoxins (Trx). The latter regulation also applies to the water-soluble portion of CFoCF1 (CF1) and includes two successive steps, namely the binding of Trx to CF1 and the subsequent reduction or oxidation of CF1. To study this process thoroughly, a new expression system for spinach Trx-f and Trx-m was designed. In the presence of dithiothreitol (DTT) both forms of the expressed Trx could reduce the disulphide bridge on the γ-subunit of CF1 and thus activate the ATPase. Trx mutants deficient in the internal, or both, cysteines of the active site were designed to study the details of the interaction. The Trx mutant proteins could still activate CF1-ATPase in the presence of DTT and they also increased the apparent affinity of CF1 for DTT. This implies that the binding of Trx to the CF1 γ-subunit induces a conformational change facilitating the reduction of the disulphide bridge, and partially explains the high efficiency of Trx as a reductant in vivo.

scholarly journals Abstract OR-9: Cryo-EM Structure of the Reconstituted Human γ-Tubulin Ring Complex

2021 ◽  
Vol 11 (Suppl_1) ◽  
pp. S10-S10
Author(s):  
Marina Serna ◽  
Fabian Zimmermann ◽  
Artur Ezquerra ◽  
Rafael Fernandez-Leiro ◽  
Jens Luders ◽  
...  
Keyword(s):  
Intracellular Transport ◽  
Expression System ◽  
Structural Features ◽  
Animal Cells ◽  
Single Particle Reconstruction ◽  
Aaa Atpase ◽  
Structural Support ◽  
Ring Complex

Background: Microtubules (MTs) are essential cytoskeletal polymers that provide structural support for the cell and play important roles in cell division, motility, and intracellular transport. The γ-tubulin ring complex (γTuRC) is the major MT nucleator in animal cells. The molecular mechanism by which the γTuRC promotes MT nucleation remains poorly understood although a template-based mechanism, remains the most widely accepted (Moritz et al., 2000, Kollman et al., 2010). According to this model γTuRC, a 2 MDa multi-subunit protein complex, forms a lock washer-like structure, in which γ-tubulin molecules are arranged in a ring-shaped structure that serves as a template for the assembly of αβ-tubulin heterodimers. Methods: We have set up an in vitro system to purify the human γTuRC using infected insect cells with recombinant baculoviruses. This complex sample was subjected to cryo-EM analysis and single-particle reconstruction. Results: We have demonstrated that RUVBL1-RUVBL2 AAA-ATPase complex (RUVBL) controls the assembly and composition of γTuRC in human cells both in vivo and in vitro. Likewise, RUVBL assembles γTuRC from a minimal set of core subunits in a heterologous co-expression system. Purified, reconstituted γTuRC has nucleation activity and resembles native γTuRC (Consolati et al., 2020, Liu et al., 2020, Wieczorek et al., 2020), as revealed by its cryo-EM structure at ~4.0 Å resolution. Conclusion: We have been able to identify novel mechanistic and structural features that determine the intricate, higher-order γTuRC architecture (Zimmermann, Serna et al., 2020).

The functional expression in yeast of two unusual acidic peroxygenases from Candolleomyces aberdarensis by adopting evolved secretion mutations

2021 ◽  
Author(s):  
Patricia Gomez de Santos ◽  
Manh Dat Hoang ◽  
Jan Kiebist ◽  
Harald Kellner ◽  
René Ullrich ◽  
...  
Keyword(s):  
Directed Evolution ◽  
Organic Compounds ◽  
Large Scale ◽  
Expression System ◽  
Veratryl Alcohol ◽  
Functional Expression ◽  
Cascade Reactions ◽  
Expression Levels ◽  
Yeast Expression System ◽  
Batch Bioreactor

Fungal unspecific peroxygenases (UPOs) are emergent biocatalysts that perform highly selective C-H oxyfunctionalizations of organic compounds, yet their heterologous production at high levels is required for their practical use in synthetic chemistry. Here, we achieved functional expression in yeast of two new unusual acidic peroxygenases from Candolleomyces ( Psathyrella ) aberdarensis ( Pab UPO) and their production at large scale in bioreactor. Our strategy was based on adopting secretion mutations from Agrocybe aegerita UPO mutant −PaDa-I variant− designed by directed evolution for functional expression in yeast, which belongs to the same phylogenetic family as Pab UPOs –long-type UPOs− and that shares 65% sequence identity. After replacing the native signal peptides by the evolved leader sequence from PaDa-I, we constructed and screened site-directed recombination mutant libraries yielding two recombinant Pab UPOs with expression levels of 5.4 and 14.1 mg/L in S. cerevisiae . These variants were subsequently transferred to P. pastoris for overproduction in fed-batch bioreactor, boosting expression levels up to 290 mg/L with the highest volumetric activity achieved to date for a recombinant peroxygenase (60,000 U/L, with veratryl alcohol as substrate). With a broad pH activity profile, ranging from 2.0 to 9.0, these highly secreted, active and stable peroxygenases are promising tools for future engineering endeavors, as well as for their direct application in different industrial and environmental settings. IMPORTANCE In this work, we incorporated several secretion mutations from an evolved fungal peroxygenase to enhance the production of active and stable forms of two unusual acidic peroxygenases. The tandem-yeast expression system based on S. cerevisiae for directed evolution and P. pastoris for overproduction in a ∼300 mg/L scale, is a versatile tool to generate UPO variants. By employing this approach, we foresee that acidic UPO variants will be more readily engineered in the near future and adapted to practical enzyme cascade reactions that can be performed over a broad pH range to oxyfunctionalize a variety of organic compounds.

Analysis of Synonymous Codon Usage Bias in D15 Gene Encoded Surface Antigen of Riemerella Anatipestifer

2013 ◽  
Vol 641-642 ◽  
pp. 597-605
Author(s):  
Bin Feng ◽  
De Kang Zhu ◽  
Xiao Jia Wang ◽  
An Chun Cheng ◽  
Ming Shu Wang
Keyword(s):  
Codon Usage ◽  
Codon Usage Bias ◽  
Homo Sapiens ◽  
Synonymous Codon ◽  
Expression System ◽  
Evolutionary Relationship ◽  
Yeast Expression System ◽  
Riemerella Anatipestifer

In order to provide a basis for understanding the evolutionary relationship and pathogenesis of Riemerella anatipestifer and selecting a appropriate host expression systems to improve the expression of target gene in vivo and in vitro, we identified the codon bias in the newly confirmed D15 gene of Riemerella anatipestifer ATCC 11845 strain and performed comparative analysis of the codon usage bias between D15 gene in R. anatipestifer and the other 10 referenced Flavobacteriaceaes by a series of online bioinformatics softwares. The results revealed that the synonymous codons with A and T at the third codon position had widely usage in the codon of D15 gene of R. anatipestifer. In addition, there were 70 rare codons in the ORF of the D15 of R. anatipestifer, and 32 codons showing distinct usage differences between R. anatipestifer and E. coli, 30 codons between R. anatipestifer and Homo sapiens, 16 codons between R. anatipestifer and yeast, indicated the yeast expression system may be more suitable for the expression of R. anatipestifer genes. The extent of codon usage bias in the D15 gene in R. anatipestifer was highly correlated with the gene expression level, therefore the results may provide useful information for gene classification and functional studies.

The in vivo distribution and dynamics of DNA topoisomerase II in Drosophila embryonic nuclei and chromosomes

1993 ◽  
Vol 51 ◽  
pp. 74-75
Author(s):  
Jason R. Swedlow ◽  
Neil Osheroff ◽  
Tim Karr ◽  
John W. Sedat ◽  
David A. Agard
Keyword(s):  
Topoisomerase Ii ◽  
Biochemical Characterization ◽  
Developmental Cycle ◽  
Dna Topoisomerase Ii ◽  
Chromosomal Distribution ◽  
Dna Topoisomerase ◽  
Ideal System ◽  
Dnase Treatment

DNA topoisomerase II is an ATP-dependent double-stranded DNA strand-passing enzyme that is necessary for full condensation of chromosomes and for complete segregation of sister chromatids at mitosis in vivo and in vitro. Biochemical characterization of chromosomes or nuclei after extraction with high-salt or detergents and DNAse treatment showed that topoisomerase II was a major component of this remnant, termed the chromosome scaffold. The scaffold has been hypothesized to be the structural backbone of the chromosome, so the localization of topoisomerase II to die scaffold suggested that the enzyme might play a structural role in the chromosome. However, topoisomerase II has not been studied in nuclei or chromosomes in vivo. We have monitored the chromosomal distribution of topoisomerase II in vivo during mitosis in the Drosophila embryo. This embryo forms a multi-nucleated syncytial blastoderm early in its developmental cycle. During this time, the embryonic nuclei synchronously progress through 13 mitotic cycles, so this is an ideal system to follow nuclear and chromosomal dynamics.

Fenofibrate Solid Dispersion for Improving Oral Bioavailability: Preparation, and Characterization and in vivo Evaluation

2020 ◽  
Vol 13 (5) ◽  
pp. 5102-5109
Author(s):  
Venu Madhav K ◽  
Somnath De ◽  
Chandra Shekar Bonagiri ◽  
Sridhar Babu Gummadi
Keyword(s):  
Oral Bioavailability ◽  
Oral Delivery ◽  
Solid Dispersions ◽  
In Vitro Release ◽  
Aqueous Solubility ◽  
Water Soluble ◽  
Scanning Calorimetry ◽  
In Vivo Evaluation

Fenofibrate (FN) is used in the treatment of hypercholesterolemia. It shows poor dissolution and poor oral bioavailability after oral administration due to high liphophilicity and low aqueous solubility. Hence, solid dispersions (SDs) of FN (FN-SDs) were develop that might enhance the dissolution and subsequently oral bioavailability. FN-SDs were prepared by solvent casting method using different carriers (PEG 4000, PEG 6000, β cyclodextrin and HP β cyclodextrin) in different proportions (0.25%, 0.5%, 0.75% and 1% w/v). FN-SDs were evaluated solubility, assay and in vitro release studies for the optimization of SD formulation. Differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM) analysis was performed for crystalline and morphology analysis, respectively. Further, optimized FN-SD formulation evaluated for pharmacokinetic performance in Wistar rats, in vivo in comparison with FN suspension.  From the results, FN-SD3 and FN-SD6 have showed 102.9 ±1.3% and 105.5±3.1% drug release, respectively in 2 h. DSC and PXRD studies revealed that conversion of crystalline to amorphous nature of FN from FT-SD formulation. SEM studies revealed the change in the orientation of FN when incorporated in SDs. The oral bioavailability FN-SD3 and FN-SD6 formulations exhibited 2.5-folds and 3.1-folds improvement when compared to FN suspension as control. Overall, SD of FN could be considered as an alternative dosage form for the enhancement of oral delivery of poorly water-soluble FN.

Traceable Peptidic Ligands that Target Ghrelin Receptors

2020 ◽  
Vol 21 (10) ◽  
pp. 955-964 ◽  
Author(s):  
Mengjie Liu ◽  
John Wade ◽  
Mohammed Akhter Hossain
Keyword(s):  
In Vivo Imaging ◽  
Peptide Hormone ◽  
Structural Features ◽  
Pharmacological Properties ◽  
Imaging Studies ◽  
Cognate Receptor ◽  
Ghrelin Receptors ◽  
Biochemical Research

: Ghrelin is a 28-amino acid octanoylated peptide hormone that is implicated in many physiological and pathophysiological processes. Specific visualization of ghrelin and its cognate receptor using traceable ligands is crucial in elucidating the localization, functions, and expression pattern of the peptide’s signaling pathway. Here 12 representative radio- and fluorescently-labeled peptide-based ligands are reviewed for in vitro and in vivo imaging studies. In particular, the focus is on their structural features, pharmacological properties, and applications in further biochemical research.

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