Designing Rigid DNA Origami Templates for Molecular Visualization Using Cryo-EM.

DNA origami, a method for constructing nanostructures from DNA, offers potential for diverse scientific and technological applications due to its ability to integrate various molecular functionalities in a programmable manner. In this study, we examined the impact of internal crossover distribution and the compositional uniformity of staple strands on the structure of multilayer DNA origami using cryogenic electron microscopy (cryo-EM) single-particle analysis. A refined DNA object was utilized as an alignment framework in a host-guest model, where we successfully resolved an 8 kDa thrombin binding aptamer (TBA) linked to the host object.

Orphan quality control shapes network dynamics and gene expression.

All eukaryotes require intricate protein networks to translate developmental signals into accurate cell fate decisions. Mutations that disturb interactions between network components often result in disease, but how the composition and dynamics of complex networks are established remains poorly understood. Here, we identify the E3 ligase UBR5 as a signaling hub that helps degrade unpaired subunits of multiple transcriptional regulators that act within a network centered on the c-Myc oncoprotein.

Cooperation between bHLH transcription factors and histones for DNA access.

The basic helix-loop-helix (bHLH) family of transcription factors recognizes DNA motifs known as E-boxes (CANNTG) and includes 108 members. Here we investigate how chromatinized E-boxes are engaged by two structurally diverse bHLH proteins: the proto-oncogene MYC-MAX and the circadian transcription factor CLOCK-BMAL1 (refs. ).

Structural basis for clearing of ribosome collisions by the RQT complex.

Translation of aberrant messenger RNAs can cause stalling of ribosomes resulting in ribosomal collisions. Collided ribosomes are specifically recognized to initiate stress responses and quality control pathways. Ribosome-associated quality control facilitates the degradation of incomplete translation products and requires dissociation of the stalled ribosomes.

An organometallic analogue of combretastatin A-4 and its apoptosis-inducing effects on lymphoma, leukemia and other tumor cells .

Hexacarbonyl[1,3-dimethoxy-5-((4'-methoxyphenyl)ethynyl)benzene]dicobalt (NAHO27), an organometallic analogue of combretastatin A-4, has been synthesized and its activity against lymphoma, leukemia, breast cancer and melanoma cells has been investigated. It was shown that NAHO27 specifically induces apoptosis in BJAB lymphoma and Nalm-6 leukemia cells at low micromolar concentration and does not affect normal leukocytes . It also proved to be active against vincristine and daunorubicin resistant leukemia cell lines with p-glycoprotein-caused multidrug resistance and showed a pronounced (550%) synergistic effect when co-applied with vincristine at very low concentrations.

KP772 overcomes multiple drug resistance in malignant lymphoma and leukemia cells in vitro by inducing Bcl-2-independent apoptosis and upregulation of Harakiri.

Despite high cure rates in pediatric patients with acute leukemia, development of resistance limits the efficacy of antileukemic therapy. Tris(1,10-phenanthroline)tris(thiocyanato-κN)lanthanum(III) (KP772) is an experimental antineoplastic agent to which multidrug-resistant cell models have shown hypersensitivity. Antiproliferative and apoptotic activities of KP772 were tested in leukemia, lymphoma and solid tumor cell lines as well as primary leukemia cells (isolated from the bone marrow of a child with acute myeloid leukemia (AML).

SAP domain forms a flexible part of DNA aperture in Ku70/80.

Nonhomologous end joining (NHEJ) is a DNA repair mechanism that religates double-strand DNA breaks to maintain genomic integrity during the entire cell cycle. The Ku70/80 complex recognizes DNA breaks and serves as an essential hub for recruitment of NHEJ components. Here, we describe intramolecular interactions of the Ku70 C-terminal domain, known as the SAP domain.

Construction of the Central Protuberance and L1 Stalk during 60S Subunit Biogenesis.

Ribosome assembly is driven by numerous assembly factors, including the Rix1 complex and the AAA ATPase Rea1. These two assembly factors catalyze 60S maturation at two distinct states, triggering poorly understood large-scale structural transitions that we analyzed by cryo-electron microscopy. Two nuclear pre-60S intermediates were discovered that represent previously unknown states after Rea1-mediated removal of the Ytm1-Erb1 complex and reveal how the L1 stalk develops from a pre-mature nucleolar to a mature-like nucleoplasmic state.

Structure of the Bcs1 AAA-ATPase suggests an airlock-like translocation mechanism for folded proteins.

Some proteins require completion of folding before translocation across a membrane into another cellular compartment. Yet the permeability barrier of the membrane should not be compromised and mechanisms have remained mostly elusive. Here, we present the structure of Saccharomyces cerevisiae Bcs1, an AAA-ATPase of the inner mitochondrial membrane.

Partially inserted nascent chain unzips the lateral gate of the Sec translocon.

The Sec translocon provides the lipid bilayer entry for ribosome-bound nascent chains and thus facilitates membrane protein biogenesis. Despite the appreciated role of the native environment in the translocon:ribosome assembly, structural information on the complex in the lipid membrane is scarce. Here, we present a cryo-electron microscopy-based structure of bacterial translocon SecYEG in lipid nanodiscs and elucidate an early intermediate state upon insertion of the FtsQ anchor domain.

Structure of the 80S ribosome-Xrn1 nuclease complex.

Messenger RNA (mRNA) homeostasis represents an essential part of gene expression, in which the generation of mRNA by RNA polymerase is counter-balanced by its degradation by nucleases. The conserved 5'-to-3' exoribonuclease Xrn1 has a crucial role in eukaryotic mRNA homeostasis by degrading decapped or cleaved mRNAs post-translationally and, more surprisingly, also co-translationally. Here we report that active Xrn1 can directly and specifically interact with the translation machinery.

The Protease ClpXP and the PAS Domain Protein DivL Regulate CtrA and Gene Transfer Agent Production in Rhodobacter capsulatus.

Several members of the () produce a conserved horizontal gene transfer vector, called the gene transfer agent (GTA), that appears to have evolved from a bacteriophage. The model system used to study GTA biology is the GTA (RcGTA), a small, tailed bacteriophage-like particle produced by a subset of the cells in a culture. The response regulator CtrA is conserved in the and is an essential regulator of RcGTA production: it controls the production and maturation of the RcGTA particle and RcGTA release from cells.

Visualizing the Assembly Pathway of Nucleolar Pre-60S Ribosomes.

Eukaryotic 60S ribosomal subunits are comprised of three rRNAs and ∼50 ribosomal proteins. The initial steps of their formation take place in the nucleolus, but, owing to a lack of structural information, this process is poorly understood. Using cryo-EM, we solved structures of early 60S biogenesis intermediates at 3.

How is childhood emotional abuse related to major depression in adulthood? The role of personality and emotion acceptance.

Accumulated evidence provides support that childhood emotional abuse (CEA) is related to adult major depressive disorder (MDD) outcomes. However, the psychological mechanisms of this relation are still not well understood. Changes in personality and emotion regulation are indicated to play a mediating role what should be examined in this paper.

Memory performance of patients with major depression in an everyday life situation.

Although patients with major depressive disorder (MDD) report severe memory impairment in their everyday life, memory tests indicate only moderate deficits. In order to clarify these conflicting observations, the present study aimed at the investigation of MDD patients' memory performance in a real everyday life situation. The study included 20 MDD patients and 20 healthy control subjects.

Architecture of the Rix1-Rea1 checkpoint machinery during pre-60S-ribosome remodeling.

Ribosome synthesis is catalyzed by ∼200 assembly factors, which facilitate efficient production of mature ribosomes. Here, we determined the cryo-EM structure of a Saccharomyces cerevisiae nucleoplasmic pre-60S particle containing the dynein-related 550-kDa Rea1 AAA(+) ATPase and the Rix1 subcomplex. This particle differs from its preceding state, the early Arx1 particle, by two massive structural rearrangements: an ∼180° rotation of the 5S ribonucleoprotein complex and the central protuberance (CP) rRNA helices, and the removal of the 'foot' structure from the 3' end of the 5.

Micro Raman spectroscopy of carbonaceous material in microfossils and meteorites: improving a method for life detection.

The identification of biosignatures in Earth's ancient rock record and detection of extraplanetary life is one of the primary goals in astrobiology. Intrinsic to this goal is the improvement of analytical techniques and protocols used to identify an unambiguous signal of life. Micro Raman spectroscopy is a nondestructive method that allows for in situ identification of a wide range of minerals and compounds.

A reduced organic carbon component in martian basalts.

The source and nature of carbon on Mars have been a subject of intense speculation. We report the results of confocal Raman imaging spectroscopy on 11 martian meteorites, spanning about 4.2 billion years of martian history.

The role of the intrinsic FAS pathway in Titanocene Y apoptosis: The mechanism of overcoming multiple drug resistance in malignant leukemia cells.

Despite the advantages in the outcome of patients with acute lymphoblastic leukemia, 25% of the affected children suffer relapses. As the response to chemotherapy is essentially determined by the development of cellular drug resistance, new drugs that are capable to overcome resistance to conventional chemotherapeutics are urgently needed. With regard to this demand, we investigated the titanium-based anticancer drug Titanocene Y.

Graphite in an Apollo 17 impact melt breccia.

We report on the detection of discrete grains of crystalline graphite and graphite whiskers (GWs) in an Apollo 17 impact melt breccia. Multiple instances of graphite and GWs within a discrete area of the sample imply that these grains are not terrestrial contamination. Both graphite and GWs are indicative of high-temperature conditions and are probably the result of the impact processes responsible for breccia formation.

Iron containing anti-tumoral agents: unexpected apoptosis-inducing activity of a ferrocene amino acid derivative.

Purpose: Due to the severe problems accompanied with multiple drug resistance (MDR), agents that can induce apoptosis independently of death-suppressing proteins are required. Here, we show that the ferrocene derivative HUNI 068 is active against cancer cells and overcomes different mechanisms of multiple drug resistance (MDR).

Methods: Proliferation inhibition was determined by using a CASY(®)CellCounter.