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The N-terminal domain of Tim23, a key component of the mitochondrial preprotein translocase, is now known to be exposed on the surface of the outer mitochondrial membrane. The spanning of two membranes on the part of Tim 23 is novel in membrane biology.

Membrane potential promotes the formation of dimers that display dynamic behavior by Tim23, an important component of the protein import machinery of the mitochondria's inner membrane. In turn, dimer dissociation is triggered when a matrix targeting sequence binds to Tim23. These all show that Tim23 significantly influences protein import.

Two new proteins MIM33 and MIM14 are components of the mitochondrial inner membrane (MIM) besides two known proteins MIM23 and MIM17 which also form a part of the complex. The import of nuclear mitochondrial preproteins takes place in a coordinated manner across the mitochondrial membrane. Translocation systems in both the outer and inner membranes take part in the process. The MIM complex can accept preproteins and cause reversible transmembrane movement with mitochondrial outer membrane and unidirectional transport through linkage with the ATP-dependent mt-Hsp70-MIM44 system.

Many cancers have the tumor suppressor p53 inactivated by mutation, making reactivation of mutant p53 with small molecules a promising strategy for the development of novel anticancer therapeutics. The oncogenic p53 mutation Y220C, which accounts for approximately 100,000 cancer cases per year, creates an extended surface crevice in the DNA-binding domain, which destabilizes p53 and causes denaturation and aggregation. Here, we describe the structure-guided design of a novel class of small-molecule Y220C stabilizers and the challenging synthetic routes developed in the process. The synthesized chemical probe MB710 , an aminobenzothiazole derivative, binds tightly to the Y220C pocket and stabilizes p53-Y220C in vitro . MB725 , an ethylamide analogue of MB710 , induced selective viability reduction in several p53-Y220C cancer cell lines while being well tolerated in control cell lines. Reduction of viability correlated with increased and selective transcription of p53 target genes such as BTG2 , p21 , PUMA , FAS , TNF , and TNFRSF10B, which promote apoptosis and cell cycle arrest, suggesting compound-mediated transcriptional activation of the Y220C mutant. Our data provide a framework for the development of a class of potent, non-toxic compounds for reactivating the Y220C mutant in anticancer therapy. [ABSTRACT FROM AUTHOR]

Summary The destabilizing p53 cancer mutation Y220C creates an extended crevice on the surface of the protein that can be targeted by small-molecule stabilizers. Here, we identify different classes of small molecules that bind to this crevice and determine their binding modes by X-ray crystallography. These structures reveal two major conformational states of the pocket and a cryptic, transiently open hydrophobic subpocket that is modulated by Cys220. In one instance, specifically targeting this transient protein state by a pyrrole moiety resulted in a 40-fold increase in binding affinity. Molecular dynamics simulations showed that both open and closed states of this subsite were populated at comparable frequencies along the trajectories. Our data extend the framework for the design of high-affinity Y220C mutant binders for use in personalized anticancer therapy and, more generally, highlight the importance of implementing protein dynamics and hydration patterns in the drug-discovery process. [ABSTRACT FROM AUTHOR]

Abstract: The promising structural features of the defect spinel-type oxide γ-Ga2O3 and its application potential as a host for new nanoscale solid solutions have been far less explored than its analog γ-alumina, which is widely used in catalysis. Therefore, new synthetic approaches are required to access transition metal-doped γ-Ga2O3 materials on the nanoscale. We have established the first microwave–hydrothermal route for the challenging incorporation of Cu2+ ions into a nanostructured γ-Ga2O3 matrix. Homogeneous γ-Ga2O3:Cu2+ materials with high surface areas are formed within less than 30 min, and the copper content can be adjusted through the synthetic parameters. The copper distribution within the spinel matrix was analyzed with a wide range of compositional, structural, spectroscopic and magnetic characterizations. [Copyright &y& Elsevier]

Summary: Specific neurosecretory cells of the Drosophila brain express insulin-like peptides (dilps), which regulate growth, glucose homeostasis, and aging. Through microarray analysis of flies in which the insulin-producing cells (IPCs) were ablated, we identified a target gene, target of brain insulin (tobi), that encodes an evolutionarily conserved α-glucosidase. Flies with lowered tobi levels are viable, whereas tobi overexpression causes severe growth defects and a decrease in body glycogen. Interestingly, tobi expression is increased by dietary protein and decreased by dietary sugar. This pattern is reminiscent of mammalian glucagon secretion, which is increased by protein intake and decreased by sugar intake, suggesting that tobi is regulated by a glucagon analog. tobi expression is also eliminated upon ablation of neuroendocrine cells that produce adipokinetic hormone (AKH), an analog of glucagon. tobi is thus a target of the insulin- and glucagon-like signaling system that responds oppositely to dietary protein and sugar. [Copyright &y& Elsevier]

Background. Patients with bicuspid aortic valves tend to develop dilatation of the ascending aorta. The aim of this study was to analyze whether or not there is any histologic difference in the aortic media of patients with a bicuspid aortic valve or a tricuspid aortic valve.Methods. A morphometric analysis of the wall of the ascending aorta was performed in 107 patients with bicuspid aortic valves undergoing aortic valve operations. The thickness of the elastic lamellae of the aortic media and the distances between the elastic lamellae were measured with the use of an image analysis system. The histologic specimens of the ascending aorta from 61 surgical patients with tricuspid aortic valve disease served as a control.Results. The patients with bicuspid aortic valves had thinner elastic lamellae of the aortic media (2.71 ± 0.23 μm) of the ascending aortic wall than the patients with tricuspid aortic valve disease (2.83 ± 0.23 μm) (p = 0.006). The patients with bicuspid aortic valves also had greater distances between the elastic lamellae (27.21 ± 8.69 μm) of the ascending aortic wall in comparison with the patients with tricuspid aortic valve disease (24.34 ± 5.32 μm) (p = 0.033). There was no difference in the total thickness of the aortic media between the groups (p = 0.62).Conclusions. Patients with a bicuspid aortic valve had thinner elastic lamellae of the aortic media and greater distances between the elastic lamellae than patients with a tricuspid aortic valve. [Copyright &y& Elsevier]

Background. Individuals with bicuspid aortic valve tend to develop a dilatation of the ascending aorta. It is controversial whether the dilated ascending aorta should be replaced with a tube graft or whether the diameter of the aorta should be reduced by reduction aortoplasty. Furthermore, it is unclear whether an external prosthetic support of the reduction aortoplasty is necessary. The aim of this study is to analyze the results of reduction aortoplasty with and without external prosthetic support.Methods. Between 1985 and 1999, a total of 115 patients with bicuspid aortic valve and dilatation of the ascending aorta underwent reduction aortoplasty in combination with other types of open-heart procedure at our institution. The diameter of the ascending aorta was measured before and early after surgery and then later between 12 and 144 months (mean 40 months) postoperatively using echocardiography and computed tomography.Results. The reduction aortoplasty decreased the internal diameter of the aorta from 48.7 ± 5.1 mm preoperatively to 36.9 ± 3.6 mm early after surgery (p = 0.0001). During follow-up, there was no increase of the aortic diameter either in patients with external prosthetic support or in 97 of 106 patients without external prosthetic support. The diameter increased only in 9 (8.5%) of 106 patients without external aortic support by 4 to 8 mm. In patients with postoperative diameter increase, the aortic diameter after operation had been higher than in patients without a postoperative increase of the aortic diameter (41.4 ± 3.1 mm vs 36.6 ± 3.4 mm; p < 0.0001).Conclusion. Reduction aortoplasty showed good long-term results in patients with bicuspid aortic valve and dilatation of the ascending aorta. Redilation of the aorta occurred only in patients with a suboptimal diameter reduction. [Copyright &y& Elsevier]

In this issue of Structure, Bista and colleagues report that inhibitors of the MDM2/p53 interaction can be designed to interact with a transiently folded α-helical segment of the MDM2 lid region. This suggests that targeting transient protein states in PPI inhibitor design could be a promising strategy to improve affinity and/or selectivity profiles. [ABSTRACT FROM AUTHOR]

• Electrochemical anodic oxidation of carbon fiber surfaces. • Gas phase derivatization of surface hydroxyl and carboxyl groups. • No influence of treatment mode on fiber surface chemistry. • Significantly higher degree of oxidation in acidic electrolyte than in alkaline one. • High ratio of surface carboxyl groups after anodic oxidation in acidic electrolyte. Carbon fibers were anodically oxidized using two different electrolytes, i.e. an alkaline aqueous ammonium bicarbonate solution (pH ≈ 8) and an acidic dilute sulfuric acid solution (pH ≈ 2). Two different treatment modes were utilized: (1) a static, discontinuous anodic oxidation treatment of a spatially fixed fiber bundle and (2) a dynamic, continuous oxidation of a fiber tow, which was dragged through the electrolyte bath with constant speed. The resulting degree of oxidation of the carbon fiber surface was analyzed by x-ray photoelectron spectroscopy. By gas-phase derivatization of the fiber surfaces the concentrations of surface hydroxyl and carboxyl groups were quantified. Good agreement between the oxygen elemental concentration determined from the derivatized surface functionalities and that extracted from x-ray photoelectron spectroscopy elemental analysis demonstrates the reliability of the derivatization results. While both treatment modes result in the same oxidation, significant differences of the oxidation behavior exist for carbon fibers treated by the two different electrolytes. This is explained by a mechanism involving the effect of electrolyte salt ions. [ABSTRACT FROM AUTHOR]

We report the case of a 55-year-old woman seen with signs of angina pectoris and dyspnea. Transesophageal echocardiography showed a floating thrombus distal to the right coronary ostium. At operation, we found a highly mobile thrombus attached to an atherosclerotic plaque distal to the right coronary ostium. The atherosclerotic lesion and the pedunculated thrombotic mass were removed without resection of the adjacent aortic wall. In our judgment, a floating mass in the ascending aorta represents an emergency and should be removed before major thromboembolic complications occur. [Copyright &y& Elsevier]

We report a patient with bicuspid aortic valve and dilatation of the ascending aorta who had previous aortic valve replacement and reduction aortoplasty with wrapping. After 4 years, reoperation because of coronary artery disease and paravalvular leakage revealed an erosion of the aortic wall due to dislocation of the wrap. This complication confirms the need for secure anchoring and good fitting of the Dacron wrap to avoid alterations of the underlying aortic wall. [Copyright &y& Elsevier]

Patients with prolonged severe cardiogenic shock requiring implantation of a biventricular assist device may develop diffuse bleeding due to alteration of hepatic and renal function and subsequent coagulopathy. Bleeding control in these patients may be difficult despite massive use of blood products. We report on the successful use of recombinant activated factor VII for control of massive bleeding after implantation of a biventricular assist device in a patient with prolonged severe cardiogenic shock. [Copyright &y& Elsevier]

p53 is an important tumor-suppressor protein that is mutated in more than 50% of cancers. Strategies for restoring normal p53 function are complicated by the oncogenic properties of mutant p53 and have not met with clinical success. To counteract mutant p53 activity, a variety of drugs with the potential to reconvert mutant p53 to an active wildtype form have been developed. However, these drugs are associated with various negative effects such as cellular toxicity, nonspecific binding to other proteins, and inability to induce a wildtype p53 response in cancer tissue. Here, we report on the effects of a curcumin analog, HO-3867, on p53 activity in cancer cells from different origins. We found that HO-3867 covalently binds to mutant p53, initiates a wildtype p53-like anticancer genetic response, is exclusively cytotoxic toward cancer cells, and exhibits high anticancer efficacy intumormodels. In conclusion, HO-3867 is a p53 mutant-reactivating drug with high clinical anticancer potential. [ABSTRACT FROM AUTHOR]

In this work, we developed and optimised a synthetic route which enables to produce by spray-coating hard, transparent and stable inorganic–organic hybrid coatings for a wide variety of different substrates (e.g. stone, stainless steel, polymethylmethacrylate, polyethylene, wood, anodized aluminum). Chemically and thermally stable acrylate-based hybrid materials embedding the zirconium oxocluster Zr4O2(OMc)12, OMc═(CH2═C(CH3)C(O)O) were prepared and UV-cured.The coatings of different compositions on different substrates were characterized by numerous analytical and spectroscopic methods such as FT-IR spectroscopy, Angle Resolved-XPS (AR-XPS), Secondary Ion Mass Spectrometry (SIMS), X-ray Absorption Spectroscopy (XAS), Environmental Scanning Electron Microscopy (ESEM) and Energy Dispersive X-ray analysis (EDX). Bulk samples were also prepared for additional characterizations. The bulk samples were analysed by FT-IR, whereas the cross-linking degree was qualitatively evaluated by swelling experiments. As far as the mechanical properties are concerned, the shear storage modulus (G′) and loss modulus (G″) were measured by Dynamical Mechanical Thermal Analysis (DMTA) technique. Moreover, the best conditions for the curing and cross-linking processes of the hybrid materials were studied up to 200 °C by using Differential Scanning Calorimetry (DSC). The thermal stability of the hybrid samples was evaluated by Thermogravimetric Analysis (TGA). [Copyright &y& Elsevier]

We showed that the human respiratory chain is organized in supramolecular assemblies of respiratory chain complexes, the respirasomes. The mitochondrial complexes I (NADH dehydrogenase) and III (cytochrome c reductase) form a stable core respirasome to which complex IV (cytochrome c oxidase) can also bind. An analysis of the state of respirasomes in patients with an isolated deficiency of single complexes provided evidence that the formation of respirasomes is essential for the assembly/stability of complex I, the major entry point of respiratory chain substrates. Genetic alterations leading to a loss of complex III prevented respirasome formation and led to the secondary loss of complex I. Therefore, primary complex III assembly deficiencies presented as combined complex III/I defects. This dependence of complex I assembly/stability on respirasome formation has important implications for the diagnosis of mitochondrial respiratory chain disorders. [ABSTRACT FROM AUTHOR]

Abstract: We report a novel heteroplasmic point mutation G8299A in the gene for mitochondrial tRNALys in a patient with progressive external ophthalmoplegia complicated by recurrent respiratory insufficiency. Biochemical analysis of respiratory chain complexes in muscle homogenate showed a combined complex I and IV deficiency. The transition does not represent a known neutral polymorphism and affects a position in the tRNA acceptor stem which is conserved in primates, leading to a destabilization of this functionally important domain. In vitro analysis of an essential maturation step of the tRNA transcript indicates the probable pathogenicity of this mutation. We hypothesize that there is a causal relationship between the novel G8299A transition and progressive external ophthalmoplegia with recurrent respiratory failure due to a depressed respiratory drive. [Copyright &y& Elsevier]

Many muscular and neurological disorders are associated with mitochondrial dysfunction and are often accompanied by changes in mitochondrial morphology. Mutations in the gene encoding OPA1 a protein required for fusion of mitochondria, are associated with hereditary autosomal dominant optic atrophy type I. Here we show that mitochondrial fragmentation correlates with processing of large isoforms of OPA1 in cybrid cells from a patient with myoclonus epilepsy and ragged-red fibers syndrome and in mouse embryonic fibroblasts harboring an error-prone mitochondrial mtDNA polymerase γ. Furthermore, processed OPA1 was observed in heart tissue derived from heart-specific TFAM knock-out mice suffering from mitochondrial cardiomyopathy and in skeletal muscles from patients suffering from mitochondrial myopathies such as myopathy encephalopathy lactic acidosis and stroke-like episodes. Dissipation of the mitochondrial membrane potential leads to fast induction of proteolytic processing of OPA1 and concomitant fragmentation of mitochondria. Recovery of mitochondrial fusion depended on protein synthesis and was accompanied by resynthesis of large isoforms of OPA1. Fragmentation of mitochondria was prevented by overexpressing OPA1. Taken together, our data indicate that proteolytic processing of OPA1 has a key role in inducing fragmentation of energetically compromised mitochondria. We present the hypothesis that this pathway regulates mitochondrial morphology and serves as an early response to prevent fusion of dysfunctional mitochondria with the functional mitochondrial network. [ABSTRACT FROM AUTHOR]

Tim9, Tim10a, and Tim10b are members of the family of small Tim proteins located in the intermembrane space of mammalian mitochondria. In yeast, members of this family act along the TIM22 import pathway during import of metabolite carriers and other integral inner membrane proteins. Here, we show that the human small proteins form two distinct hetero-oligomeric complexes. A 70-kDa complex that contains Tim9 and Tim10a and a Tim9-10a-10b that is part of a higher molecular weight assembly of 450 kDa. This distribution among two complexes suggests Tim10b to be the functional homologue of yeast Tim12. Both human complexes are tightly associated with the inner membrane and, compared with yeast, soluble 70-kDa complexes appear to be completely absent in the intermembrane space. Thus, the function of soluble 70-kDa complexes as trans-site receptors for incoming carrier proteins is not conserved from lower to higher eukaryotes. During import, the small Tim complexes directly interact with human adenine nucleotide translocator (ANT) in transit in a metal-dependent manner. For insertion of carrier preproteins into the inner membrane, the human small Tim proteins directly interact with human Tim22, the putative insertion pore of the TIM22 translocase. However, in contrast to yeast, only a small fraction of Tim9Tim10a-Tim10b complex is in a stable association with Tim22. We conclude that different mechanisms and specific requirements for import and insertion of mammalian carrier preproteins have evolved in higher eukaryotes. [ABSTRACT FROM AUTHOR]