The structure of natively iodinated bovine thyroglobulin

Thyroglobulin is a homodimeric glycoprotein that is essential for the generation of thyroid hormones in vertebrates. Upon secretion into the lumen of follicles in the thyroid gland, tyrosine residues within the protein become iodinated to produce monoiodotyrosine (MIT) and diiodotyrosine (DIT). A subset of evolutionarily conserved pairs of DIT (and MIT) residues can then engage in oxidative coupling reactions that yield either thyroxine (T4; produced from coupling of a DIT `acceptor' with a DIT `donor') or triiodothyronine (T3; produced from coupling of a DIT acceptor with an MIT donor). Although multiple iodotyrosine residues have been identified as potential donors and acceptors, the specificity and structural context of the pairings (i.e. which donor is paired with which acceptor) have remained unclear. Here, single-particle cryogenic electron microscopy (cryoEM) was used to generate a high-resolution reconstruction of bovine thyroglobulin (2.3 Å resolution in the core region and 2.6 Å overall), allowing the structural characterization of two post-reaction acceptor–donor pairs as well as tyrosine residues modified as MIT and DIT. A substantial spatial separation between donor Tyr149 and acceptor Tyr24 was observed, suggesting that for thyroxine synthesis significant peptide motion is required for coupling at the evolutionarily conserved thyroglobulin amino-terminus.

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Characterization of drug interaction of pore-exposed tyrosine residues

Intrinsic Activity ◽

10.25006/ia.1.s1-a3.15 ◽

2013 ◽

Vol 1 (Suppl. 1) ◽

pp. A3.15

Author(s):

Yaprak Dönmez Çakıl

Keyword(s):

Drug Interaction ◽

Tyrosine Residues

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An Unprecedented Cyano-Induced Sodium Nitrite-Catalyzed C(sp3)-H and C(sp2)-H Coupling Reaction

Current Organic Synthesis ◽

10.2174/1570179415666180622102458 ◽

2018 ◽

Vol 15 (7) ◽

pp. 989-994 ◽

Cited By ~ 1

Author(s):

Ling Li ◽

Bo Su ◽

Yuxiu Liu ◽

Qingmin Wang

Keyword(s):

Sodium Nitrite ◽

Oxidative Coupling ◽

High Resolution Mass Spectrometry ◽

Coupling Reaction ◽

13C Nmr Spectroscopy ◽

Coupling Reactions ◽

Reaction Conditions ◽

1H And 13C Nmr ◽

Oxidative Coupling Reaction ◽

Oxidative Coupling Reactions

Aim and Objective: During the investigation of sodium nitrite-catalyzed oxidative coupling reaction of aryls, an unprecedented C(sp2)-H and C(sp3)-H coupling of substituted 2-aryl acetonitrile was found. Materials and Methods: The structure of the coupled product was confirmed by 1H and 13C NMR spectroscopy and high-resolution mass spectrometry (HRMS), and comparison of its derivatives with known compounds. The effects of methoxy group in the benzene ring on the reaction were evaluated. Results: The optimized reaction conditions are summarized as follows: CF3SO3H/substrate = 1.5 equiv., NaNO2/substrate = 0.3 equiv., CH3CN as solvent. 2-(4-Methoxyphenyl)acetonitrile and 2-(3,4,5- trimethoxyphenyl)acetonitrile could also generate C(sp2)-H and C(sp3)-H coupling. The coupling reaction occurred as a typical radial mechanism. Conclusion: An unprecedented cyano-induced, NaNO2-catalyzed oxidative C(sp3)-H and C(sp2)-H coupling was reported. The reaction proceeded under very mild conditions, using O2 in the air as terminal oxidant. The unique oxidative manner might provide more inspiration for the development of intriguing oxidative coupling reactions.

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Insights on autophagosome–lysosome tethering from structural and biochemical characterization of human autophagy factor EPG5

Communications Biology ◽

10.1038/s42003-021-01830-x ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Sung-Eun Nam ◽

Yiu Wing Sunny Cheung ◽

Thanh Ngoc Nguyen ◽

Michael Gong ◽

Samuel Chan ◽

...

Keyword(s):

Biochemical Characterization ◽

Late Endosome ◽

Multisystem Disorder ◽

Cytoplasmic Material ◽

Disease Mutations ◽

Evolutionarily Conserved ◽

Overall Stability ◽

Transport Vesicle ◽

Molecular Effects

AbstractPivotal to the maintenance of cellular homeostasis, macroautophagy (hereafter autophagy) is an evolutionarily conserved degradation system that involves sequestration of cytoplasmic material into the double-membrane autophagosome and targeting of this transport vesicle to the lysosome/late endosome for degradation. EPG5 is a large-sized metazoan protein proposed to serve as a tethering factor to enforce autophagosome–lysosome/late endosome fusion specificity, and its deficiency causes a severe multisystem disorder known as Vici syndrome. Here, we show that human EPG5 (hEPG5) adopts an extended “shepherd’s staff” architecture. We find that hEPG5 binds preferentially to members of the GABARAP subfamily of human ATG8 proteins critical to autophagosome–lysosome fusion. The hEPG5–GABARAPs interaction, which is mediated by tandem LIR motifs that exhibit differential affinities, is required for hEPG5 recruitment to mitochondria during PINK1/Parkin-dependent mitophagy. Lastly, we find that the Vici syndrome mutation Gln336Arg does not affect the hEPG5’s overall stability nor its ability to engage in interaction with the GABARAPs. Collectively, results from our studies reveal new insights into how hEPG5 recognizes mature autophagosome and establish a platform for examining the molecular effects of Vici syndrome disease mutations on hEPG5.

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Spatial segregation of mixed-sized counterions in dendritic polyelectrolytes

Scientific Reports ◽

10.1038/s41598-021-87448-9 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

J. S. Kłos ◽

J. Paturej

Keyword(s):

Electrostatic Interactions ◽

Spatial Separation ◽

Excluded Volume ◽

The Core ◽

Bjerrum Length ◽

Two Component ◽

Conformational Properties ◽

Dynamics Simulations ◽

Two Parameters ◽

Swelling Factor

AbstractLangevin dynamics simulations are utilized to study the structure of a dendritic polyelectrolyte embedded in two component mixtures comprised of conventional (small) and bulky counterions. We vary two parameters that trigger conformational properties of the dendrimer: the reduced Bjerrum length, $$\lambda _B^*$$ λ B ∗ , which controls the strength of electrostatic interactions and the number fraction of the bulky counterions, $$f_b$$ f b , which impacts on their steric repulsion. We find that the interplay between the electrostatic and the counterion excluded volume interactions affects the swelling behavior of the molecule. As compared to its neutral counterpart, for weak electrostatic couplings the charged dendrimer exists in swollen conformations whose size remains unaffected by $$f_b$$ f b . For intermediate couplings, the absorption of counterions into the pervaded volume of the dendrimer starts to influence its conformation. Here, the swelling factor exhibits a maximum which can be shifted by increasing $$f_b$$ f b . For strong electrostatic couplings the dendrimer deswells correspondingly to $$f_b$$ f b . In this regime a spatial separation of the counterions into core–shell microstructures is observed. The core of the dendrimer cage is preferentially occupied by the conventional ions, whereas its periphery contains the bulky counterions.

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Isolation and Molecular Characterization of the Romaine Lettuce Phylloplane Mycobiome

Journal of Fungi ◽

10.3390/jof7040277 ◽

2021 ◽

Vol 7 (4) ◽

pp. 277

Author(s):

Danny Haelewaters ◽

Hector Urbina ◽

Samuel Brown ◽

Shannon Newerth-Henson ◽

M. Catherine Aime

Keyword(s):

Lactuca Sativa ◽

New Combinations ◽

Food Spoilage ◽

Human Pathogens ◽

Plant Leaves ◽

Romaine Lettuce ◽

Future Studies ◽

The Core ◽

American Agriculture

Romaine lettuce (Lactuca sativa) is an important staple of American agriculture. Unlike many vegetables, romaine lettuce is typically consumed raw. Phylloplane microbes occur naturally on plant leaves; consumption of uncooked leaves includes consumption of phylloplane microbes. Despite this fact, the microbes that naturally occur on produce such as romaine lettuce are for the most part uncharacterized. In this study, we conducted culture-based studies of the fungal romaine lettuce phylloplane community from organic and conventionally grown samples. In addition to an enumeration of all such microbes, we define and provide a discussion of the genera that form the “core” romaine lettuce mycobiome, which represent 85.5% of all obtained isolates: Alternaria, Aureobasidium, Cladosporium, Filobasidium, Naganishia, Papiliotrema, Rhodotorula, Sampaiozyma, Sporobolomyces, Symmetrospora and Vishniacozyma. We highlight the need for additional mycological expertise in that 23% of species in these core genera appear to be new to science and resolve some taxonomic issues we encountered during our work with new combinations for Aureobasidiumbupleuri and Curvibasidium nothofagi. Finally, our work lays the ground for future studies that seek to understand the effect these communities may have on preventing or facilitating establishment of exogenous microbes, such as food spoilage microbes and plant or human pathogens.

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Novel Polyion Complex Micelles Entrapping Enzyme Molecules in the Core. 2. Characterization of the Micelles Prepared at Nonstoichiometric Mixing Ratios†

Langmuir ◽

10.1021/la981087t ◽

1999 ◽

Vol 15 (12) ◽

pp. 4208-4212 ◽

Cited By ~ 90

Author(s):

Atsushi Harada ◽

Kazunori Kataoka

Keyword(s):

Polyion Complex ◽

Polyion Complex Micelles ◽

Mixing Ratios ◽

The Core ◽

Enzyme Molecules ◽

Complex Micelles

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Analysis of Advanced PWR Loading Schemes for Transuranic Incineration in Thorium

Volume 1: Plant Operations, Maintenance, Engineering, Modifications, Life Cycle and Balance of Plant; Nuclear Fuel and Materials; Radiation Protection and Nuclear Technology Applications ◽

10.1115/icone21-15328 ◽

2013 ◽

Cited By ~ 2

Author(s):

Benjamin A. Lindley ◽

N. Zara Zainuddin ◽

Fausto Franceschini ◽

Geoffrey T. Parks

Keyword(s):

Temperature Coefficient ◽

Preliminary Analysis ◽

Detrimental Effect ◽

Spatial Separation ◽

Trade Off ◽

The Core ◽

Positive Reactivity ◽

Fuel Pin ◽

Control Rods

It is difficult to perform multiple recycle of transuranic (TRU) isotopes in PWRs as the moderator temperature coefficient (MTC) tends to become positive after a few recycles and the core may have positive reactivity when fully voided. Due to the favorable impact on the MTC and void coefficient fostered by use of thorium (Th), the possibility of performing Th-TRU multiple-recycle in reduced-moderation PWRs (RMPWRs) is under consideration. The simplest way to reduce the moderation in a PWR is to increase the fuel pin diameter. This configuration improves the trade-off between achievable burn-up and MTC, but is ultimately limited by thermal-hydraulic constraints. Heterogeneous recycle with the bred uranium (U3) and the TRU are arranged in separate pins was found to be neutronically preferable to a homogeneous configuration. Spatial separation also enables the U3 and TRU to be refueled on different batch schemes. These techniques allow satisfactory discharge burn-up while ensuring negative MTC and fully voided reactivity, with the pin diameter of a standard PWR increased from 9.5 mm to 11 mm. Reactivity control is a key challenge due to the reduced worth of neutron absorbers and their detrimental effect on the void coefficients, especially when diluted, as is the case for soluble boron. It seems necessary to control the core using control rods to keep the fully voided reactivity negative. A preliminary analysis indicates that this is feasible.

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