Production of cobalamin and sirohaem in Bacillus megaterium: an investigation into the role of the branchpoint chelatases sirohydrochlorin ferrochelatase (SirB) and sirohydrochlorin cobalt chelatase (CbiX)

2002 ◽  
Vol 30 (4) ◽  
pp. 610-613 ◽  
Author(s):  
H. K. Leech ◽  
E. Raux-Deery ◽  
P. Heathcote ◽  
M. J. Warren
Keyword(s):  
Sequence Analysis ◽  
Bacillus Megaterium ◽  
Primary Structure ◽  
Comparative Sequence Analysis ◽  
Functional Complementation ◽  
In Vitro Assays ◽  
Cobalamin Biosynthesis ◽  
Redox Centre

One of the four operons required for cobalamin biosynthesis in Bacillus megaterium is also associated with sirohaem synthesis, and contains three genes, sirA, sirB and sirC. By undertaking functional complementation experiments and in vitro assays using recombinantly produced enzymes, we have been able to demonstrate that (1) SirA acts as a uroporphyrinogen III methyltransferase, transforming uroporphyrinogen III into precorrin-2, (2) SirC acts as an NAD+ dehydrogenase, responsible for the oxidation of precorrin-2 into sirohydrochlorin, and (3) SirB acts as a ferrochelatase, responsible for the insertion of a ferrous ion into sirohydrochlorin to give sirohaem. Comparative sequence analysis reveals that the primary structure of SirB is highly similar to that of the cobalt chelatase involved in cobalamin biosynthesis in Bacillus megaterium, CbiX, with the exception that CbiX contains a C-terminal histidine-rich motif. Surprisingly, CbiX has been shown (using EPR) to contain a 4Fe-4S centre, a redox centre that is absent from SirB.

scholarly journals Dual Role of Integrin Alpha-6 in Glioblastoma: Supporting Stemness in Proneural Stem-Like Cells While Inducing Radioresistance in Mesenchymal Stem-Like Cells

Cancers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 3055
Author(s):  
Elisabetta Stanzani ◽  
Leire Pedrosa ◽  
Guillaume Bourmeau ◽  
Oceane Anezo ◽  
Aleix Noguera-Castells ◽  
...  
Keyword(s):  
Cellular Heterogeneity ◽  
In Vitro Assays ◽  
Rna Seq ◽  
Promising Target ◽  
Damage Response ◽  
Integrin Alpha 6 ◽  
And Control ◽  
Improve Patient

Therapeutic resistance after multimodal therapy is the most relevant cause of glioblastoma (GBM) recurrence. Extensive cellular heterogeneity, mainly driven by the presence of GBM stem-like cells (GSCs), strongly correlates with patients’ prognosis and limited response to therapies. Defining the mechanisms that drive stemness and control responsiveness to therapy in a GSC-specific manner is therefore essential. Here we investigated the role of integrin a6 (ITGA6) in controlling stemness and resistance to radiotherapy in proneural and mesenchymal GSCs subtypes. Using cell sorting, gene silencing, RNA-Seq, and in vitro assays, we verified that ITGA6 expression seems crucial for proliferation and stemness of proneural GSCs, while it appears not to be relevant in mesenchymal GSCs under basal conditions. However, when challenged with a fractionated protocol of radiation therapy, comparable to that used in the clinical setting, mesenchymal GSCs were dependent on integrin a6 for survival. Specifically, GSCs with reduced levels of ITGA6 displayed a clear reduction of DNA damage response and perturbation of cell cycle pathways. These data indicate that ITGA6 inhibition is able to overcome the radioresistance of mesenchymal GSCs, while it reduces proliferation and stemness in proneural GSCs. Therefore, integrin a6 controls crucial characteristics across GBM subtypes in GBM heterogeneous biology and thus may represent a promising target to improve patient outcomes.

scholarly journals Primary structure and comparative sequence analysis of an insect apolipoprotein. Apolipophorin-III from Manduca sexta.

1987 ◽  
Vol 262 (24) ◽  
pp. 11794-11800 ◽  
Author(s):  
K D Cole ◽  
G P Fernando-Warnakulasuriya ◽  
M S Boguski ◽  
M Freeman ◽  
J I Gordon ◽  
...  
Keyword(s):  
Sequence Analysis ◽  
Manduca Sexta ◽  
Primary Structure ◽  
Comparative Sequence Analysis ◽  
Comparative Sequence ◽  
Apolipophorin Iii

scholarly journals LncRNA GHET1 Promotes Esophageal Squamous Cell Carcinoma Cells Proliferation and Invasion via Induction of EMT

2017 ◽  
Vol 32 (4) ◽  
pp. 403-408 ◽  
Author(s):  
Hongfen Liu ◽  
Qiang Zhen ◽  
Yakun Fan
Keyword(s):  
Squamous Cell Carcinoma ◽  
Esophageal Squamous Cell Carcinoma ◽  
Cell Carcinoma ◽  
Squamous Cell ◽  
Noncoding Rna ◽  
In Vitro Assays ◽  
Migration And Invasion ◽  
Advanced Tumor

Background Recent studies have shown that long noncoding RNA (IncRNA) gastric carcinoma highly expressed transcript 1 (GHET1) was involved in the progression of tumors. However, the role of GHET1 in esophageal squamous cell carcinoma (ESCC) remains unclear. Methods The expression of IncRNA GHET1 was examined in 55 paired ESCC tissues and adjacent nontumor tissues. Molecular and cellular techniques were used to explore the role of GHET1 on ESCC cells. Results Our data showed that GHET1 expression was significantly increased in ESCC tissues and cell lines. High GHET1 expression in ESCC tissues was significantly associated with poor differentiation, advanced tumor nodes metastasis stage, and lymph node metastasis. GHET1 showed high sensitivity and specificity for diagnosing ESCC. Our data from in vitro assays showed that GHET1 inhibition suppressed ESCC cells proliferation, migration, and invasion, and induced cells apoptosis. Furthermore, western blot showed that GHET1 inhibition significantly decreased the expression of vimentin and N-cadherin while it increased the expression of E-cadherin. Conclusions Our study indicates that GHET1 acts as an oncogene in ESCC and may represent a novel therapeutic target for the treatment of ESCC patients.

Exploring the role of dosing procedure and chemical properties in in vitro assays using a fish gill cell line

2009 ◽  
Vol 153 (2) ◽  
pp. S89
Author(s):  
Kristin Schirmer ◽  
Katrin Tanneberger ◽  
Nynke I. Kramer ◽  
Frans J.M. Busser ◽  
Joop L.M. Hermens ◽  
...  
Keyword(s):  
Cell Line ◽  
Chemical Properties ◽  
In Vitro Assays ◽  
Fish Gill ◽  
Gill Cell ◽  
And Chemical Properties

scholarly journals The Role of Vitamin C in Cancer Prevention and Therapy: A Literature Review

Antioxidants ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1894
Author(s):  
Marcelo Villagran ◽  
Jorge Ferreira ◽  
Miquel Martorell ◽  
Lorena Mardones
Keyword(s):  
Clinical Trials ◽  
Vitamin C ◽  
Cancer Prevention ◽  
Randomized Study ◽  
Regulation Of Gene Expression ◽  
Water Soluble ◽  
In Vitro Assays ◽  
High Concentration

Vitamin C is a water-soluble antioxidant associated with the prevention of the common cold and is also a cofactor of hydrolases that participate in the synthesis of collagen and catecholamines, and in the regulation of gene expression. In cancer, vitamin C is associated with prevention, progression, and treatment, due to its general properties or its role as a pro-oxidant at high concentration. This review explores the role of vitamin C in cancer clinical trials and the aspects to consider in future studies, such as plasmatic vitamin C and metabolite excretion recording, and metabolism and transport of vitamin C into cancer cells. The reviewed studies show that vitamin C intake from natural sources can prevent the development of pulmonary and breast cancer, and that vitamin C synergizes with gemcitabine and erlotinib in pancreatic cancer. In vitro assays reveal that vitamin C synergizes with DNA-methyl transferase inhibitors. However, vitamin C was not associated with cancer prevention in a Mendelian randomized study. In conclusion, the role of vitamin C in the prevention and treatment of cancer is still an ongoing area of research. It is necessary that new phase II and III clinical trials be performed to collect stronger evidence of the therapeutic role of vitamin C in cancer.

scholarly journals HIF-1α is a key mediator of the lung inflammatory potential of lithium-ion battery particles

2019 ◽  
Vol 16 (1) ◽  
Author(s):  
Violaine Sironval ◽  
Mihaly Palmai-Pallag ◽  
Rita Vanbever ◽  
François Huaux ◽  
Jorge Mejia ◽  
...  
Keyword(s):  
Inflammatory Responses ◽  
Hypoxia Inducible Factor ◽  
Lithium Ion ◽  
In Vitro Assays ◽  
Inhalation Toxicity ◽  
Cobalt Nickel ◽  
Occupational Settings

Abstract Background Li-ion batteries (LIB) are increasingly used worldwide. They are made of low solubility micrometric particles, implying a potential for inhalation toxicity in occupational settings and possibly for consumers. LiCoO2 (LCO), one of the most used cathode material, induces inflammatory and fibrotic lung responses in mice. LCO also stabilizes hypoxia-inducible factor (HIF) -1α, a factor implicated in inflammation, fibrosis and carcinogenicity. Here, we investigated the role of cobalt, nickel and HIF-1α as determinants of toxicity, and evaluated their predictive value for the lung toxicity of LIB particles in in vitro assays. Results By testing a set of 5 selected LIB particles (LCO, LiNiMnCoO2, LiNiCoAlO2) with different cobalt and nickel contents, we found a positive correlation between their in vivo lung inflammatory activity, and (i) Co and Ni particle content and their bioaccessibility and (ii) the stabilization of HIF-1α in the lung. Inhibition of HIF-1α with chetomin or PX-478 blunted the lung inflammatory response to LCO in mice. In IL-1β deficient mice, HIF-1α was the upstream signal of the inflammatory lung response to LCO. In vitro, the level of HIF-1α stabilization induced by LIB particles in BEAS-2B cells correlated with the intensity of lung inflammation induced by the same particles in vivo. Conclusions We conclude that HIF-1α, stabilized in lung cells by released Co and Ni ions, is a mechanism-based biomarker of lung inflammatory responses induced by LIB particles containing Co/Ni. Documenting the Co/Ni content of LIB particles, their bioaccessibility and their capacity to stabilize HIF-1α in vitro can be used to predict the lung inflammatory potential of LIB particles.

scholarly journals Identification and functional analysis of enzymes required for precorrin-2 dehydrogenation and metal ion insertion in the biosynthesis of sirohaem and cobalamin in Bacillus megaterium

2003 ◽  
Vol 370 (2) ◽  
pp. 505-516 ◽  
Author(s):  
Evelyne RAUX ◽  
Helen K. LEECH ◽  
Richard BECK ◽  
Heidi L. SCHUBERT ◽  
Patricio J. SANTANDER ◽  
...  
Keyword(s):  
Bacillus Megaterium ◽  
Metal Ion ◽  
Enzyme Assay ◽  
Sequence Alignments ◽  
Rich Region ◽  
In Vitro Synthesis ◽  
Cobalamin Biosynthesis ◽  
High Degree ◽  
Degree Of Similarity

In Bacillus megaterium, the hemAXBCDL genes were isolated and were found to be highly similar to the genes from Bacillus subtilis that are required for the conversion of glutamyl-tRNA into uroporphyrinogen III. Overproduction and purification of HemC (porphobilinogen deaminase) and -D (uroporphyrinogen III synthase) allowed these enzymes to be used for the in vitro synthesis of uroporphyrinogen III from porphobilinogen. A second smaller cluster of three genes (termed sirABC) was also isolated and found to encode the enzymes that catalyse the transformation of uroporphyrinogen III into sirohaem on the basis of their ability to complement a defined Escherichia coli (cysG) mutant. The functions of SirC and -B were investigated by direct enzyme assay, where SirC was found to act as a precorrin-2 dehydrogenase, generating sirohydrochlorin, and SirB was found to act as a ferrochelatase responsible for the final step in sirohaem synthesis. CbiX, a protein found encoded within the main B. megaterium cobalamin biosynthetic operon, shares a high degree of similarity with SirB and acts as the cobaltochelatase associated with cobalamin biosynthesis by inserting cobalt into sirohydrochlorin. CbiX contains an unusual histidine-rich region in the C-terminal portion of the protein, which was not found to be essential in the chelation process. Sequence alignments suggest that SirB and CbiX share a similar active site to the cobaltochelatase, CbiK, from Salmonella enterica.

Plastoquinone-9 biosynthesis in cyanobacteria differs from that in plants and involves a novel 4-hydroxybenzoate solanesyltransferase

2012 ◽  
Vol 442 (3) ◽  
pp. 621-629 ◽  
Author(s):  
Radin Sadre ◽  
Christian Pfaff ◽  
Stephan Buchkremer
Keyword(s):  
Biosynthetic Pathway ◽  
In Vitro Assays ◽  
Transport Chain ◽  
In Vivo Labelling ◽  
Membrane Bound ◽  
Transformation Processes ◽  
Synechocystis Sp

PQ-9 (plastoquinone-9) has a central role in energy transformation processes in cyanobacteria by mediating electron transfer in both the photosynthetic as well as the respiratory electron transport chain. The present study provides evidence that the PQ-9 biosynthetic pathway in cyanobacteria differs substantially from that in plants. We identified 4-hydroxybenzoate as being the aromatic precursor for PQ-9 in Synechocystis sp. PCC6803, and in the present paper we report on the role of the membrane-bound 4-hydroxybenzoate solanesyltransferase, Slr0926, in PQ-9 biosynthesis and on the properties of the enzyme. The catalytic activity of Slr0926 was demonstrated by in vivo labelling experiments in Synechocystis sp., complementation studies in an Escherichia coli mutant with a defect in ubiquinone biosynthesis, and in vitro assays using the recombinant as well as the native enzyme. Although Slr0926 was highly specific for the prenyl acceptor substrate 4-hydroxybenzoate, it displayed a broad specificity with regard to the prenyl donor substrate and used not only solanesyl diphosphate, but also a number of shorter-chain prenyl diphosphates. In combination with in silico data, our results indicate that Slr0926 evolved from bacterial 4-hydroxybenzoate prenyltransferases catalysing prenylation in the course of ubiquinone biosynthesis.

scholarly journals Histamine H2 receptor radioligands: triumphs and challenges

2021 ◽  
Author(s):  
Steffen Pockes ◽  
Katharina Tropmann
Keyword(s):  
Receptor Expression ◽  
In Vitro Assays ◽  
Histamine H2 Receptor ◽  
Drug Candidates ◽  
Carbon 14 ◽  
The Central Nervous System ◽  
And Function ◽  
Role And Function

Since the discovery of the histamine H2 receptor (H2R), radioligands were among the most powerful tools to investigate its role and function. Initially, radiolabeling was used to investigate human and rodent tissues regarding their receptor expression. Later, radioligands gained increasing significance as pharmacological tools in in vitro assays. Although tritium-labeling was mainly used for this purpose, labeling with carbon-14 is preferred for metabolic studies of drug candidates. After the more-or-less successful application of numerous labeled H2R antagonists, the recent development of the G protein-biased radioligand [3H]UR-KAT479 represents another step forward to elucidate the widely unknown role of the H2R in the central nervous system through future studies.

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