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Terminal Hydride Complex of High-Spin Mn
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Correction to “Terminal Hydride Complex of High-Spin Mn”
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Isolation and Study of Ruthenium–Cobalt Oxo Cubanes Bearing a High-Valent, Terminal Ru V –Oxo with Significant Oxyl Radical Character
High-valent Ru V -oxo intermediates have long been proposed in catalytic oxidation chemistry, but investigations into their electronic and chemical properties have been limited due to their reactive nature and rarity. The incorporation of Ru into the [Co 3 O 4 ] subcluster via the single-step assembly reaction of Co II (OAc) 2 (H 2 O) 4 (OAc = acetate), perruthenate (RuO 4 - ), and pyridine (py) yielded an unprecedented Ru(O)Co 3 (μ 3 -O) 4 (OAc) 4 (py) 3 cubane featuring an isolable, yet reactive, RuV-oxo moiety. EPR, ENDOR, and DFT studies reveal a valence-localized [Ru V (S = 1/2)Co III 3(S = 0)O 4 ] configuration and non-negligible covalency in the cubane core. Significant oxyl radical character in the Ru V -oxo unit is experimentally demonstrated by radical coupling reactions between the oxo cubane and both 2,4,6-tri-tert-butylphenoxyl and trityl radicals. The oxo cubane oxidizes organic substrates and, notably, reacts with water to form an isolable μ-oxo bis-cubane complex [(py) 3 (OAc) 4 Co 3 (μ 3 -O) 4 Ru]-O-[RuCo 3 (μ 3 -O) 4 (OAc) 4 (py) 3 ]. Redox activity of the Ru V -oxo fragment is easily tuned by the electron-donating ability of the distal pyridyl ligand set at the Co sites demonstrating strong electronic communication throughout the entire cubane cluster. Natural bond orbital calculations reveal cooperative orbital interactions of the [Co 3 O 4 ] unit in supporting the Ru V -oxo moiety via a strong π-electron donation.
Allosteric control of dynamin-related protein 1 through a disordered C-terminal Short Linear Motif
Abstract The mechanochemical GTPase dynamin-related protein 1 (Drp1) catalyzes mitochondrial and peroxisomal fission, but the regulatory mechanisms remain ambiguous. Here we find that a conserved, intrinsically disordered, six-residue Short Linear Motif at the extreme Drp1 C-terminus, named CT-SLiM, constitutes a critical allosteric site that controls Drp1 structure and function in vitro and in vivo. Extension of the CT-SLiM by non-native residues, or its interaction with the protein partner GIPC-1, constrains Drp1 subunit conformational dynamics, alters self-assembly properties, and limits cooperative GTP hydrolysis, surprisingly leading to the fission of model membranes in vitro. In vivo, the involvement of the native CT-SLiM is critical for productive mitochondrial and peroxisomal fission, as both deletion and non-native extension of the CT-SLiM severely impair their progression. Thus, contrary to prevailing models, Drp1-catalyzed membrane fission relies on allosteric communication mediated by the CT-SLiM, deceleration of GTPase activity, and coupled changes in subunit architecture and assembly-disassembly dynamics.
Redox chemistry and H-atom abstraction reactivity of a terminal zirconium( iv ) oxo compound mediated by an appended cobalt( i ) center
Bimetallic cooperativity is demonstrated with a Co/Zr complex featuring both nucleophilic Zr( iv ) oxo and redox active Co sites.
Super-electrophiles of tri- and tetra-anions stabilized by selected terminal groups and their role in binding noble gas atoms
Stabilization of multiply-charged clusters in the gas phase has been a topic of great interest not only because of their potential applications as weakly-coordinating anions, but also for their ability to promote unusual reactions.
A framework for comparing the energy production of photovoltaic modules using 2-, 3-, and 4-terminal tandem cells
Energy production, rather than efficiency, is the most important metric for comparing different configurations of tandem solar cells (2T, 3T, 4T), as each interconnection technique has its own advantages and disadvantages.
Cooperative dihydrogen activation with unsupported uranium–metal bonds and characterization of a terminal U( iv ) hydride
The cooperation between U( iii ) and Al( i ) centres leads to dihydrogen reduction.
Histone H3 N-terminal mimicry drives a novel network of methyl-effector interactions
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Structural and functional analyses of the N-terminal domain of the A subunit of a Bacillus megaterium spore germinant receptor
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Cryo-EM structure of RNA-induced tau fibrils reveals a small C-terminal core that may nucleate fibril formation
In neurodegenerative diseases including Alzheimer’s and amyotrophic lateral sclerosis, proteins that bind RNA are found in aggregated forms in autopsied brains. Evidence suggests that RNA aids nucleation of these pathological aggregates; however, the mechanism has not been investigated at the level of atomic structure. Here, we present the 3.4-Å resolution structure of fibrils of full-length recombinant tau protein in the presence of RNA, determined by electron cryomicroscopy (cryo-EM). The structure reveals the familiar in-register cross-β amyloid scaffold but with a small fibril core spanning residues Glu391 to Ala426, a region disordered in the fuzzy coat in all previously studied tau polymorphs. RNA is bound on the fibril surface to the positively charged residues Arg406 and His407 and runs parallel to the fibril axis. The fibrils dissolve when RNase is added, showing that RNA is necessary for fibril integrity. While this structure cannot exist simultaneously with the tau fibril structures extracted from patients’ brains, it could conceivably account for the nucleating effects of RNA cofactors followed by remodeling as fibrils mature.
Structural basis for the interaction of Shiga toxin 2a with a C-terminal peptide of ribosomal P stalk proteins
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The structure of the Thermococcus gammatolerans McrB N-terminal domain reveals a new mode of substrate recognition and specificity among McrB homologs
McrBC is a two-component, modification-dependent restriction system that cleaves foreign DNA-containing methylated cytosines. Previous crystallographic studies have shown that Escherichia coli McrB uses a base-flipping mechanism to recognize these modified substrates with high affinity. The side chains stabilizing both the flipped base and the distorted duplex are poorly conserved among McrB homologs, suggesting that other mechanisms may exist for binding modified DNA. In this paper we present the structures of the Thermococcus gammatolerans McrB DNA-binding domain (TgΔ185) both alone and in complex with a methylated DNA substrate at 1.68 and 2.27 Å resolution, respectively. The structures reveal that TgΔ185 consists of a YT521-B homology (YTH) domain, which is commonly found in eukaryotic proteins that bind methylated RNA and is structurally unrelated to the E. coli McrB DNA-binding domain. Structural superposition and co-crystallization further show that TgΔ185 shares a conserved aromatic cage with other YTH domains, which forms the binding pocket for a flipped-out base. Mutational analysis of this aromatic cage supports its role in conferring specificity for the methylated adenines, whereas an extended basic surface present in TgΔ185 facilitates its preferential binding to duplex DNA rather than RNA. Together, these findings establish a new binding mode and specificity among McrB homologs and expand the biological roles of YTH domains.
A terminal [alpha]3-galactose modification regulates an E3 ubiquitin ligase subunit in Toxoplasma go
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Structure of S. pombe telomerase protein Pof8 C-terminal domain is an xRRM conserved among LARP7 proteins
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