scholarly journals Functional role of respiratory supercomplexes in mice: SCAF1 relevance and segmentation of the Qpool

2020 ◽  
Vol 6 (26) ◽  
pp. eaba7509 ◽  
Author(s):  
Enrique Calvo ◽  
Sara Cogliati ◽  
Pablo Hernansanz-Agustín ◽  
Marta Loureiro-López ◽  
Adela Guarás ◽  
...  
Keyword(s):  
Quantitative Data ◽  
Functional Role ◽  
Physiological Role ◽  
Oxidative Capacity ◽  
Oxygen Species ◽  
Wild Type ◽  
Assembly Factor ◽  
Native Gel ◽  
Blue Native

Mitochondrial respiratory complexes assemble into supercomplexes (SC). Q-respirasome (III2 + IV) requires the supercomplex assembly factor (SCAF1) protein. The role of this factor in the N-respirasome (I + III2 + IV) and the physiological role of SCs are controversial. Here, we study C57BL/6J mice harboring nonfunctional SCAF1, the full knockout for SCAF1, or the wild-type version of the protein and found that exercise performance is SCAF1 dependent. By combining quantitative data–independent proteomics, 2D Blue native gel electrophoresis, and functional analysis of enriched respirasome fractions, we show that SCAF1 confers structural attachment between III2 and IV within the N-respirasome, increases NADH-dependent respiration, and reduces reactive oxygen species (ROS). Furthermore, the expression of AOX in cells and mice confirms that CI-CIII superassembly segments the CoQ in two pools and modulates CI-NADH oxidative capacity.

scholarly journals Functional role of respiratory supercomplexes in mice: segmentation of the Qpool and SCAF1

2019 ◽  
Author(s):  
Enrique Calvo ◽  
Sara Cogliati ◽  
Pablo Hernansanz-Agustín ◽  
Marta Loureiro-López ◽  
Adela Guarás ◽  
...  
Keyword(s):  
Quantitative Data ◽  
Functional Role ◽  
Physiological Role ◽  
Oxidative Capacity ◽  
Wild Type ◽  
Knock Out ◽  
Transport Chain ◽  
Native Gel ◽  
Blue Native

SummaryMitochondrial respiratory complexes assemble into different forms of supercomplexes (SC). In particular, SC III2+IV require the SCAF1 protein. However, the structural role of this factor in the formation of the respirasome (I+III2+IV) and the physiological role of SCs are controversial. Here, we study C57BL/6J mice harbouring either non-functional SCAF1, the full knock-out for SCAF1 or the wild-type version of the protein and found a growth and exercise phenotype due to the lack of functional SCAF1. By combining quantitative data-independent proteomics, high resolution 2D Blue Native Gel Electrophoresis and functional analysis of enriched respirasome fractions, we show that SCAF1 confers structural attachment between III2 and IV within the respirasome, increases NADH-dependent respiration and reduces ROS production. Furthermore, through the expression of AOX in cells and mice we confirm that CI-CIII superassembly segments the CoQ in two pools and modulates CI-NADH oxidative capacity. These data demonstrate that SC assembly, regulated by SCAF1, modulates the functionality of the electron transport chain.

scholarly journals Bub1 mediates cell death in response to chromosome missegregation and acts to suppress spontaneous tumorigenesis

2007 ◽  
Vol 179 (2) ◽  
pp. 255-267 ◽  
Author(s):  
Karthik Jeganathan ◽  
Liviu Malureanu ◽  
Darren J. Baker ◽  
Susan C. Abraham ◽  
Jan M. van Deursen
Keyword(s):  
Cell Death ◽  
Chromosome Segregation ◽  
Physiological Role ◽  
Mitotic Checkpoint ◽  
Critical Threshold ◽  
Wild Type ◽  
Checkpoint Protein ◽  
Chromosome Missegregation ◽  
Mitotic Checkpoint Protein

The physiological role of the mitotic checkpoint protein Bub1 is unknown. To study this role, we generated a series of mutant mice with a gradient of reduced Bub1 expression using wild-type, hypomorphic, and knockout alleles. Bub1 hypomorphic mice are viable, fertile, and overtly normal despite weakened mitotic checkpoint activity and high percentages of aneuploid cells. Bub1 haploinsufficient mice, which have a milder reduction in Bub1 protein than Bub1 hypomorphic mice, also exhibit reduced checkpoint activity and increased aneuploidy, but to a lesser extent. Although cells from Bub1 hypomorphic and haploinsufficient mice have similar rates of chromosome missegregation, cell death after an aberrant separation decreases dramatically with declining Bub1 levels. Importantly, Bub1 hypomorphic mice are highly susceptible to spontaneous tumors, whereas Bub1 haploinsufficient mice are not. These findings demonstrate that loss of Bub1 below a critical threshold drives spontaneous tumorigenesis and suggest that in addition to ensuring proper chromosome segregation, Bub1 is important for mediating cell death when chromosomes missegregate.

scholarly journals Deletion of the rpoZ gene, encoding the ω subunit of RNA polymerase, results in pleiotropic surface-related phenotypes in Mycobacterium smegmatis

Microbiology ◽  
2006 ◽  
Vol 152 (6) ◽  
pp. 1741-1750 ◽  
Author(s):  
Renjith Mathew ◽  
Raju Mukherjee ◽  
Radhakrishnan Balachandar ◽  
Dipankar Chatterji
Keyword(s):  
Rna Polymerase ◽  
Mycobacterium Smegmatis ◽  
Biofilm Formation ◽  
Physiological Role ◽  
Wild Type ◽  
Gene Encoding ◽  
Biofilm Growth ◽  
Mutant Bacterium ◽  
Sliding Motility

The ω subunit, the smallest subunit of bacterial RNA polymerase, is known to be involved in maintaining the conformation of the β′ subunit and aiding its recruitment to the rest of the core enzyme assembly in Escherichia coli. It has recently been shown in Mycobacterium smegmatis, by creating a deletion mutation of the rpoZ gene encoding ω, that the physiological role of the ω subunit also includes providing physical protection to β′. Interestingly, the mutant had altered colony morphology. This paper demonstrates that the mutant mycobacterium has pleiotropic phenotypes including reduced sliding motility and defective biofilm formation. Analysis of the spatial arrangement of biofilms by electron microscopy suggests that the altered phenotype of the mutant arises from a deficiency in generation of extracellular matrix. Complementation of the mutant strain with a copy of the wild-type rpoZ gene integrated in the bacterial chromosome restored both sliding motility and biofilm formation to the wild-type state, unequivocally proving the role of ω in the characteristics observed for the mutant bacterium. Analysis of the cell wall composition demonstrated that the mutant bacterium had an identical glycopeptidolipid profile to the wild-type, but failed to synthesize the short-chain mycolic acids characteristic of biofilm growth in M. smegmatis.

scholarly journals Subunit Topology of Two 20S Proteasomes from Haloferax volcanii

2003 ◽  
Vol 185 (1) ◽  
pp. 165-174 ◽  
Author(s):  
Steven J. Kaczowka ◽  
Julie A. Maupin-Furlow
Keyword(s):  
Gel Electrophoresis ◽  
Structural Information ◽  
Haloferax Volcanii ◽  
20S Proteasome ◽  
Wild Type ◽  
Epitope Tag ◽  
Α Subunit ◽  
Native Gel ◽  
Recombinant Technology

ABSTRACT Haloferax volcanii, a halophilic archaeon, synthesizes three different proteins (α1, α2, and β) which are classified in the 20S proteasome superfamily. The α1 and β proteins alone form active 20S proteasomes; the role of α2, however, is not clear. To address this, α2 was synthesized with an epitope tag and purified by affinity chromatography from recombinant H. volcanii. The α2 protein copurified with α1 and β in a complex with an overall structure and peptide-hydrolyzing activity comparable to those of the previously described α1-β proteasome. Supplementing buffers with 10 mM CaCl2 stabilized the halophilic proteasomes in the absence of salt and enabled them to be separated by native gel electrophoresis. This facilitated the discovery that wild-type H. volcanii synthesizes more than one type of 20S proteasome. Two 20S proteasomes, the α1-β and α1-α2-β proteasomes, were identified during stationary phase. Cross-linking of these enzymes, coupled with available structural information, suggested that the α1-β proteasome was a symmetrical cylinder with α1 rings on each end. In contrast, the α1-α2-β proteasome appeared to be asymmetrical with homo-oligomeric α1 and α2 rings positioned on separate ends. Inter-α-subunit contacts were only detected when the ratio of α1 to α2 was perturbed in the cell using recombinant technology. These results support a model that the ratio of α proteins may modulate the composition and subunit topology of 20S proteasomes in the cell.

scholarly journals Effect of Blueberry Anthocyanins Malvidin and Glycosides on the Antioxidant Properties in Endothelial Cells

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Wuyang Huang ◽  
Yunming Zhu ◽  
Chunyang Li ◽  
Zhongquan Sui ◽  
Weihong Min
Keyword(s):  
Oxidative Stress ◽  
Reactive Oxygen Species ◽  
Endothelial Cells ◽  
Functional Food ◽  
Functional Role ◽  
Antioxidant Properties ◽  
Heme Oxygenase 1 ◽  
Oxygen Species ◽  
Good Resource

The objective of this research was to survey the antioxidant functional role of the main anthocyanins of blueberries in endothelial cells. Changes on the reactive oxygen species (ROS), xanthine oxidase-1 (XO-1), superoxide dismutase (SOD), and heme oxygenase-1 (HO-1) in cells of malvidin and the two glycosides were investigated. The results showed that these anthocyanins decreased the levels of ROS and XO-1 but increased the levels of SOD and HO-1. Glycosides improved the antioxidant capacity of malvidin to a great extent. The changes in the antioxidant properties of malvidin-3-glucoside were more pronounced than malvidin-3-galactoside. Variation in levels of malvidin-3-glucoside and malvidin-3-galactoside had a significant impact on antioxidant properties to different extents. It indicates that blueberries are a good resource of anthocyanins, which can protect cells from oxidative deterioration and use blueberry as a potential functional food to prevent diseases related to oxidative stress.

The physiological role of reactive oxygen species (ROS) in lens and corneal epithelial cells

2011 ◽  
Vol 89 (s248) ◽  
pp. 0-0 ◽  
Author(s):  
M LOU ◽  
KY XING ◽  
Q PAN ◽  
YN HUO ◽  
WY QIU ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Epithelial Cells ◽  
Physiological Role ◽  
Reactive Oxygen ◽  
Oxygen Species ◽  
Corneal Epithelial Cells ◽  
Corneal Epithelial

Contribution of R domain phosphoserines to the function of CFTR studied in Fischer rat thyroid epithelia

2000 ◽  
Vol 279 (5) ◽  
pp. L835-L841 ◽  
Author(s):  
Olafur Baldursson ◽  
Herbert A. Berger ◽  
Michael J. Welsh
Keyword(s):  
Functional Role ◽  
Transmembrane Conductance Regulator ◽  
Regulatory Domain ◽  
Wild Type ◽  
Transmembrane Conductance ◽  
Dependent Protein ◽  
Rat Thyroid ◽  
Cystic Fibrosis Transmembrane

The regulatory domain of cystic fibrosis transmembrane conductance regulator (CFTR) regulates channel activity when several serines are phosphorylated by cAMP-dependent protein kinase. To further define the functional role of individual phosphoserines, we studied CFTR containing previously studied and new serine to alanine mutations. We expressed these constructs in Fischer rat thyroid epithelia and measured transepithelial Cl− current. Mutation of four in vivo phosphorylation sites, Ser660, Ser737, Ser795, and Ser813 (S-Quad-A), substantially decreased cAMP-stimulated current, suggesting that these four sites account for most of the phosphorylation-dependent response. Mutation of either Ser660 or Ser813 alone significantly decreased current, indicating that these residues play a key role in phosphorylation-dependent stimulation. However, neither Ser660 nor Ser813 alone increased current to wild-type levels; both residues were required. Changing Ser737 to alanine increased current above wild-type levels, suggesting that phosphorylation of Ser737 may inhibit current in wild-type CFTR. These data help define the functional role of regulatory domain phosphoserines and suggest interactions between individual phosphoserines.

scholarly journals Transmission of Functional, Wild-Type Mitochondria and the Fittest mtDNA to the Next Generation: Bottleneck Phenomenon, Balbiani Body, and Mitophagy

Genes ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 104 ◽  
Author(s):  
Waclaw Tworzydlo ◽  
Malgorzata Sekula ◽  
Szczepan M. Bilinski
Keyword(s):  
Membrane Potential ◽  
Respiratory Activity ◽  
Metabolic Energy ◽  
Oxygen Species ◽  
Deleterious Mutations ◽  
Next Generation ◽  
Wild Type ◽  
Female Germline ◽  
Final Effect

The most important role of mitochondria is to supply cells with metabolic energy in the form of adenosine triphosphate (ATP). As synthesis of ATP molecules is accompanied by the generation of reactive oxygen species (ROS), mitochondrial DNA (mtDNA) is highly vulnerable to impairment and, consequently, accumulation of deleterious mutations. In most animals, mitochondria are transmitted to the next generation maternally, i.e., exclusively from female germline cells (oocytes and eggs). It has been suggested, in this context, that a specialized mechanism must operate in the developing oocytes enabling escape from the impairment and subsequent transmission of accurate (devoid of mutations) mtDNA from one generation to the next. Literature survey suggest that two distinct and irreplaceable pathways of mitochondria transmission may be operational in various animal lineages. In some taxa, the mitochondria are apparently selected: functional mitochondria with high inner membrane potential are transferred to the cells of the embryo, whereas those with low membrane potential (overloaded with mutations in mtDNA) are eliminated by mitophagy. In other species, the respiratory activity of germline mitochondria is suppressed and ROS production alleviated leading to the same final effect, i.e., transmission of undamaged mitochondria to offspring, via an entirely different route.

scholarly journals Expression of a Mitochondrial Peroxiredoxin Prevents Programmed Cell Death in Leishmania donovani

2006 ◽  
Vol 5 (5) ◽  
pp. 861-870 ◽  
Author(s):  
Simone Harder ◽  
Meike Bente ◽  
Kerstin Isermann ◽  
Iris Bruchhaus
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Mitochondrial Membrane ◽  
Leishmania Donovani ◽  
Physiological Role ◽  
Logarithmic Phase ◽  
Insect Vector ◽  
Oxygen Species ◽  
Late Logarithmic Phase

ABSTRACT Leishmania promastigote cells transmitted by the insect vector get phagocytosed by macrophages and convert into the amastigote form. During development and transformation, the parasites are exposed to various concentrations of reactive oxygen species, which can induce programmed cell death (PCD). We show that a mitochondrial peroxiredoxin (LdmPrx) protects Leishmania donovani from PCD. Whereas this peroxiredoxin is restricted to the kinetoplast area in promastigotes, it covers the entire mitochondrion in amastigotes, accompanied by dramatically increased expression. A similar change in the expression pattern was observed during the growth of Leishmania from the early to the late logarithmic phase. Recombinant LdmPrx shows typical peroxiredoxin-like enzyme activity. It is able to detoxify organic and inorganic peroxides and prevents DNA from hydroxyl radical-induced damage. Most notably, Leishmania parasites overexpressing this peroxiredoxin are protected from hydrogen peroxide-induced PCD. This protection is also seen in promastigotes grown to the late logarithmic phase, also characterized by high expression of this peroxiredoxin. Apparently, the physiological role of this peroxiredoxin is stabilization of the mitochondrial membrane potential and, as a consequence, inhibition of PCD through removal of peroxides.

scholarly journals Contemporary evidence on the physiological role of reactive oxygen species in human sperm function

2015 ◽  
Vol 32 (4) ◽  
pp. 509-520 ◽  
Author(s):  
Stefan S. Du Plessis ◽  
Ashok Agarwal ◽  
Jacques Halabi ◽  
Eva Tvrda
Keyword(s):  
Reactive Oxygen Species ◽  
Physiological Role ◽  
Reactive Oxygen ◽  
Human Sperm ◽  
Sperm Function ◽  
Oxygen Species
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