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11 results on '"Sergunin, Artur"'

7. Specific heme interaction modulates the conformational dynamics and function of p53

Author

Sergunin, Artur, Martínková, Markéta, and Dračínská, Helena

Subjects
transcription factor, protein p53, transkripční faktor, heme, senzorové proteiny, p53 protein, intrinsically disordered proteins, hem, sensor proteins, vnitřně neuspořádané proteiny
Abstract

Tumor suppressor p53 is one of the most studied proteins in terms of cancer and the mechanism of its formation. The general function of p53 is based on the transcriptional regulation of various genes, which can differently influence numerous cellular processes. Recent studies revealed a relationship between p53 and iron homeostasis within the cell. In particular, p53 was shown to interact with a molecule of heme, and this interaction ultimately disrupts the DNA-binding ability of p53 and promotes its proteasomal degra- dation. This work focuses on a detailed description of heme binding to the p53. For this purpose, we isolated two forms of p53, heme-free and heme-bound. We discovered that conformational dynamics of heme-free and heme-bound p53 differ, with the latter exhibi- ting a higher degree of flexibility. We also confirmed previous reports that heme indeed interacts with a cysteine residue in a specific manner. However, heme binding does not disrupt the oligomeric state of p53 or its native zinc binding ability. Finally, we showed that heme-bound p53 exhibits severely impaired DNA-binding ability as opposed to the heme-free form. Keywords: heme, sensor proteins, p53 protein, transcription factor, intrinsically disor- dered proteins

Published
2022

9. Multiple roles for iron in microbial physiology: bacterial oxygen sensing by heme-based sensors

Author

Sergunin, Artur, Vávra, Jakub, Pašek, Dominik, Shimizu, Toru, and Martínková, Markéta

Abstract

Bacterial oxygen sensing embodies a fascinating interplay between evolutionary pressures and physiological adaptations to varying oxygen levels. Throughout Earth's history, the composition of the atmosphere has undergone significant changes, from anoxic conditions to the gradual accumulation of oxygen. In response, microbial life has evolved diverse strategies to cope with these shifting oxygen levels, ranging from anaerobic metabolism to oxygen-dependent pathways crucial for energy production and cellular processes typical for eukaryotic, multicellular organisms. Of particular interest is the role of iron in bacterial oxygen sensing systems, which play pivotal roles in adaptation to changing oxygen levels. Only free iron, heme-iron, and non-heme iron directly sense oxygen. These iron-containing proteins, such as heme-containing sensors and iron-sulfur cluster proteins, regulate the expression of genes and activity of enzymes involved in oxidative stress defence, virulence, and biofilm formation, highlighting their significance in bacterial pathogenesis and environmental adaptation. Special attention in the review is paid to the mechanisms of oxygen detection and signal transduction from heme-containing sensing to functional domains in the case of bacterial heme-based oxygen sensors.

Published
2024
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10. Monitoring the Kinase Activity of Heme-Based Oxygen Sensors and Its Dependence on O 2 and Other Ligands Using Phos-Tag Electrophoresis.

Author

Vávra J, Sergunin A, Shimizu T, and Martínková M

Subjects
Ligands, Bacteria metabolism, Electrophoresis, Polyacrylamide Gel, Oxygen metabolism, Adenosine Triphosphate metabolism, Heme metabolism, Proteins
Abstract

The nonradioactive method, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) in the presence of Phos-tag (Phos-tag electrophoresis), is used to evaluate a kinase autophosphorylation and/or phosphotransfer reaction from a kinase/ATP to its protein substrate. This method outperforms radioisotope methods using [ 32 P]ATP for detecting trace amounts of phosphorylated protein in fresh protein preparations. Phos-tag electrophoresis has been used to perform detailed analyses of the kinase activity of a heme-based oxygen sensor-specifically, a globin-coupled histidine kinase from the soil bacterium Anaeromyxobacter sp. Fw109-5 (AfGcHK)., (© 2023. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Published
2023
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11. Signal transduction mechanisms in heme-based globin-coupled oxygen sensors with a focus on a histidine kinase ( Af GcHK) and a diguanylate cyclase (YddV or Ec DosC).

Author

Vávra J, Sergunin A, Jeřábek P, Shimizu T, and Martínková M

Subjects
Histidine Kinase chemistry, Histidine Kinase metabolism, Oxygen metabolism, Signal Transduction, Hemoglobins, Heme chemistry, Myoglobin metabolism
Abstract

Heme is a vital cofactor of proteins with roles in oxygen transport (e.g. hemoglobin), storage (e.g. myoglobin), and activation (e.g. P450) as well as electron transfer (e.g. cytochromes) and many other functions. However, its structural and functional role in oxygen sensing proteins differs markedly from that in most other enzymes, where it serves as a catalytic or functional center. This minireview discusses the mechanism of signal transduction in two heme-based oxygen sensors: the histidine kinase Af GcHK and the diguanylate cyclase YddV ( Ec DosC), both of which feature a heme-binding domain containing a globin fold resembling that of hemoglobin and myoglobin., (© 2022 Walter de Gruyter GmbH, Berlin/Boston.)

Published
2022
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