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Advances in Thermal Imaging
- 2021
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Ingår i: Journal of Thermal Biology. - 0306-4565.
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Annan publikation (refereegranskat)abstract
- Thermal imaging, or more correctly infrared thermography, has been widely applied to studies of animal and human biology (see Burnay et al. 1988; McCafferty 2007; Soerensen and Pedersen 2015; Fernandez-Cuevas et al., 2015; Tattersall 2016). This technique provides non-contact measurement of surface temperature, allowing real-time recording of the spatial temperature distribution of a body region, physical structure or habitat of interest. Thermal imaging technology has advanced rapidly in the last decade and is now becoming a key tool in thermal biology. Technological advances include greater spatial and temporal resolution, increased capacity to record and store high resolution radiometric video, as well as reduced device size and portability. In addition, high-quality thermal imaging devices are quickly becoming more affordable, meaning thermal imaging is an increasingly common item of the research tool-kit in many pure and applied fields. The aim of this Special Issue was to highlight how advances in thermal imaging can be used to answer important questions in biology, and to demonstrate how the combination of this technology with novel analytical methods can further advance our conceptual understanding of thermal biology.
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- Österlund, Nicklas, et al.
(författare)
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A hairpin motif in the Amyloid-β peptide is important for formation of disease-related oligomers
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The Amyloid-β (Aβ) peptide is an aggregation-prone peptide linked to neurodegeneration in Alzheimer’s disease (AD). Aβ self-assembles spontaneously in aqueous solution to form aggregates of various sizes, with smaller pre-fibrillar oligomeric aggregates being especially neurotoxic. Such small oligomers are however difficult to study as they are transient, low abundant and heterogenous. We here use a combination of native ion mobility-mass spectrometry and molecular dynamics simulations to systematically study the structure and assembly mechanisms of Aβ oligomers in vitro. It is found that oligomers cannot be formed by a peptide variant that does not have propensity to fold into a β-hairpin motif present in the wild type Aβ peptide. This specific structure motif seems to be a more important determinant for aggregation than the overall hydrophobicity of the peptide. Introduction of an intramolecular disulfide bond in the Aβ peptide increases oligomerization, even though the monomeric peptide is not stabilized in the hairpin conformation. This is probably achieved by pre-arranging the peptide in a conformation which is compatible with oligomeric, but not fibrillar structures. As oligomerization is driven by formation of the hairpin motif it was furthermore possible to decrease the oligomer population by truncating one of the β-strands, and thus decreasing the hairpin propensity of the peptide. These studies provide increased understanding of the earliest steps in Aβ aggregation where species related to AD toxicity might be formed. Prevention of Aβ folding into the hairpin conformation, or specific binding to the hairpin motif could be strategies to design AD therapies.
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- Lobez, Ana Paula, et al.
(författare)
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Electron transfer in the respiratory chain at low salinity
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Recent studies have established that cellular electrostatic interactions are more influential than assumed previously. Here, we used cryo-EM and performed steady-state kinetic studies to investigate electrostatic interactions between cytochrome (cyt.) c and the complex (C) III-IV supercomplex from Saccharomyces cerevisiae at low salinity. The kinetic studies show a sharp transition with a Hill coefficient ≥2, which together with the cryo-EM data at 2.4 Å resolution indicate multiple cyt. c molecules bound along the supercomplex surface. Previously unresolved negatively charged loops of CIII subunits Qcr6 and Qcr9 become structured to interact with cyt. c. In addition, the higher resolution allowed us to identify water molecules in proton pathways of CIV and previously unresolved cardiolipin molecules. In conclusion, the lowered electrostatic screening renders engagement of multiple cyt. c molecules that are directed by electrostatically structured CIII loops to conduct electron transfer between CIII and CIV.
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- Smirnova, Irina, et al.
(författare)
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Molecular basis for stimulation of cytochrome c oxidase activity by detergents
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Cytochrome c oxidase (CytcO) is an integral membrane protein, which catalyzes four-electron reduction of oxygen linked to proton uptake and pumping. Amphipathic molecules bind in sites near the so-called K proton pathway of CytcO to reversibly modulate its activity. However, purification of CytcO for mechanistic studies typically involves the use of detergents, which may interfere with binding of these regulatory molecules. Here, we investigated the CytcO enzymatic activity as well as intramolecular electron transfer linked to proton transfer upon addition of different detergents to bovine heart mitoplasts. The CytcO activity increased upon addition of alkyl glucosides (DDM and DM) and the steroid analog GDN. The maximum stimulating effect was observed for DDM and DM, and the half-stimulating effect correlated with their CMC values. With GDN the stimulation effect was smaller and occurred at a concentration higher than CMC. A kinetic analysis suggests that the stimulation of activity is due to removal of a ligand bound near the K proton pathway, which indicates that in the native membrane this site is occupied to yield a lower than maximal possible CytcO activity. Possible functional consequences are discussed.
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- Wú, Fēi, 1993-, et al.
(författare)
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Structure of the II2-III2-IV2 mitochondrial supercomplex from the parasite Perkinsus marinus
- 2024
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Respiratory complexes have co-evolved into supercomplexes in different clades to sustain energy production at the basis of eukaryotic life. In this study, using cryogenic electron microscopy, we determined the 2.1 Å resolution structure of a 104-subunit II2-III2-IV2 supercomplex from the parasite Perkinsus marinus, related to Apicomplexa, capable of complete electron transport from succinate to molecular oxygen. A feature of the parasite is the association of two copies of complex II via the apicomplexan subunit SDHG that interacts with both complexes III and IV and bridge the supercomplex. In the c1 state, we identified two protein factors, ISPR1 and ISPR2 bound on the surface of complex III, where Cytochrome c docks, acting as negative regulators. The acquisition of 15 specific subunits to complex IV results in its lateral offset, increasing the distance between the Cytochrome c electron donor and acceptor sites. The domain homologous to canonical mitochondria-encoded transmembrane subunit COX2 is made of three separate polypeptides encoded in the nucleus, and their correct assembly is a prerequisite for electron transport in the supercomplex. Subunits Cytochrome b and COX1 comprise a +2 frameshift introduced during protein synthesis by the mitoribosome. Among 114 modelled endogenous lipids, we detect a direct contribution to the formation of the divergent supercomplex and its functional sites, including assembly of CII and ubiquinone binding. Together, our findings expose the uniqueness of the principal components of bioenergetics in the mitochondria of parasites.
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