Near-Atomic Resolution Structure of a Plant Geminivirus Determined by Electron Cryomicroscopy.

African cassava mosaic virus is a whitefly-transmitted geminivirus which forms unique twin particles of incomplete icosahedra that are joined at five-fold vertices, building an unusual waist. How its 22 capsomers interact within a half-capsid or across the waist is unknown thus far. Using electron cryo-microscopy and image processing, we determined the virion structure with a resolution of 4.

A critical examination of the recently reported crystal structures of the human SMN protein.

A recent publication by Seng et al. in this journal reports the crystallographic structure of refolded, full-length SMN protein and two disease-relevant derivatives thereof. Here, we would like to suggest that at least two of the structures reported in that study are incorrect.

Autophagic digestion of Leishmania major by host macrophages is associated with differential expression of BNIP3, CTSE, and the miRNAs miR-101c, miR-129, and miR-210.

Background: Autophagy participates in innate immunity by eliminating intracellular pathogens. Consequently, numerous microorganisms have developed strategies to impair the autophagic machinery in phagocytes. In the current study, interactions between Leishmania major (L.

The structure of apo ArnA features an unexpected central binding pocket and provides an explanation for enzymatic cooperativity.

The bacterial protein ArnA is an essential enzyme in the pathway leading to the modification of lipid A with the pentose sugar 4-amino-4-deoxy-L-arabinose. This modification confers resistance to polymyxins, which are antibiotics that are used as a last resort to treat infections with multiple drug-resistant Gram-negative bacteria. ArnA contains two domains with distinct catalytic functions: a dehydrogenase domain and a transformylase domain.

The catalytically inactive tyrosine phosphatase HD-PTP/PTPN23 is a novel regulator of SMN complex localization.

The survival motor neuron (SMN) complex fulfils essential functions in the assembly of snRNPs, which are key components in the splicing of pre-mRNAs. Little is known about the regulation of SMN complex activity by posttranslational modification despite its complicated phosphorylation pattern. Several phosphatases had been implicated in the regulation of SMN, including the nuclear phosphatases PPM1G and PP1γ.

In vivo single-molecule imaging identifies altered dynamics of calcium channels in dystrophin-mutant C. elegans.

Single-molecule (SM) fluorescence microscopy allows the imaging of biomolecules in cultured cells with a precision of a few nanometres but has yet to be implemented in living adult animals. Here we used split-GFP (green fluorescent protein) fusions and complementation-activated light microscopy (CALM) for subresolution imaging of individual membrane proteins in live Caenorhabditis elegans (C. elegans).

Structure of BamA, an essential factor in outer membrane protein biogenesis.

Outer membrane protein (OMP) biogenesis is an essential process for maintaining the bacterial cell envelope and involves the β-barrel assembly machinery (BAM) for OMP recognition, folding and assembly. In Escherichia coli this function is orchestrated by five proteins: the integral outer membrane protein BamA of the Omp85 superfamily and four associated lipoproteins. To unravel the mechanism underlying OMP folding and insertion, the structure of the E.

Phosphoregulation of the human SMN complex.

The survival motor neuron (SMN) complex is a macromolecular machine comprising 9 core proteins: SMN, Gemins2-8 and unrip in vertebrates. It performs tasks in RNA metabolism including the cytoplasmic assembly of spliceosomal small nuclear ribonucleoprotein particles (snRNPs). The SMN complex also localizes to the nucleus, where it accumulates in Cajal Bodies (CB) and may function in transcription and/or pre-mRNA splicing.

Giants, dwarfs and the environment - metamorphic trait plasticity in the common frog.

In order to understand adaptation processes and population dynamics, it is central to know how environmental parameters influence performance of organisms within populations, including their phenotypes. The impact of single or few particular parameters in concert was often assessed in laboratory and mesocosm experiments. However, under natural conditions, with many biotic and abiotic factors potentially interacting, outcomes on phenotypic changes may be different.

Chemical camouflage--a frog's strategy to co-exist with aggressive ants.

Whereas interspecific associations receive considerable attention in evolutionary, behavioural and ecological literature, the proximate bases for these associations are usually unknown. This in particular applies to associations between vertebrates with invertebrates. The West-African savanna frog Phrynomantis microps lives in the underground nest of ponerine ants (Paltothyreus tarsatus).

The Arabidopsis thaliana phosphate starvation responsive gene AtPPsPase1 encodes a novel type of inorganic pyrophosphatase.

Background: Low inorganic phosphate (Pi) availability triggers metabolic responses to maintain the intracellular phosphate homeostasis in plants. One crucial adaptive mechanism is the immediate cleavage of Pi from phosphorylated substrates; however, phosphohydrolases that function in the cytosol and putative substrates have not been characterized yet. One candidate gene is Arabidopsis thaliana At1g73010 encoding an uncharacterized enzyme with homology to the haloacid dehalogenase (HAD) superfamily.

RioK1, a new interactor of protein arginine methyltransferase 5 (PRMT5), competes with pICln for binding and modulates PRMT5 complex composition and substrate specificity.

Protein arginine methylation plays a critical role in differential gene expression through modulating protein-protein and protein-DNA/RNA interactions. Although numerous proteins undergo arginine methylation, only limited information is available on how protein arginine methyltransferases (PRMTs) identify their substrates. The human PRMT5 complex consists of PRMT5, WD45/MEP50 (WD repeat domain 45/methylosome protein 50), and pICln and catalyzes the symmetrical arginine dimethylation of its substrate proteins.

Lead expansion and virtual screening of Indinavir derivate HIV-1 protease inhibitors using pharmacophoric - shape similarity scoring function.

Indinavir (Crivaxan®) is a potent inhibitor of the HIV (human immunodeficiency virus) protease. This enzyme has an important role in viral replication and is considered to be very attractive target for new antiretroviral drugs. However, it becomes less effective due to highly resistant new viral strains of HIV, which have multiple mutations in their proteases.

Lack of association of genetic variants in genes of the endocannabinoid system with anorexia nervosa.

Background: Several lines of evidence indicate that the central cannabinoid receptor 1 (CNR1) as well as the major endocannabinoid degrading enzymes fatty acid amide hydrolase (FAAH), N-acylethanolamine-hydrolyzing acid amidase (NAAA) and monoglyceride lipase (MGLL) are implicated in mediating the orexigenic effects of cannabinoids. The aim of this study was to analyse whether nucleotide sequence variations in the CNR1, FAAH, NAAA and MGLL genes are associated with anorexia nervosa (AN).

Methods: We analysed the association of a previously described (AAT)n repeat in the 3' flanking region of CNR1 as well as a total of 15 single nucleotide polymorphisms (SNPs) representative of regions with restricted haplotype diversity in CNR1, FAAH, NAAA or MGLL in up to 91 German AN trios (patient with AN and both biological parents) using the transmission-disequilibrium-test (TDT).

The dance floor of meiosis: evolutionary conservation of nuclear envelope attachment and dynamics of meiotic telomeres.

Segregation of the homologous chromosomes is the most important feature of meiosis as it ensures the faithful haploidization of the genome. It essentially depends on an accurate prearrangement of chromosomes that culminates in a precise and unambiguous pairing of the homologs, which in turn is a prere - quisite for their correct segregation. Pairing with the right partner is accompanied by, moreover it implicitly requires characteristic chromosomal movements that, remarkably, appear to be driven by the chromosomal ends.

Transmembrane protein Sun2 is involved in tethering mammalian meiotic telomeres to the nuclear envelope.

Dynamic repositioning of telomeres is a unique feature of meiotic prophase I that is highly conserved among eukaryotes. At least in fission yeast it was shown to be required for proper alignment and recombination of homologous chromosomes. On entry into meiosis telomeres attach to the nuclear envelope and transiently cluster at a limited area to form a chromosomal bouquet.

Loss of 11q and 16q in Wilms tumors is associated with anaplasia, tumor recurrence, and poor prognosis.

Allele loss of chromosome arms 11q and 16q in Wilms tumors has been associated with different clinical parameters in prior studies. To substantiate these findings in a large collection of tumors treated according to the GPOH/SIOP protocol and to narrow down critical regions, we performed loss of heterozygosity (LOH) analyses of chromosome arms 11q and 16q on 225 Wilms tumors. On chromosome arm 11q an overall rate of allele loss of 19.

Hypoxia-mediated activation of Dll4-Notch-Hey2 signaling in endothelial progenitor cells and adoption of arterial cell fate.

Adequate response to low oxygen levels (hypoxia) by hypoxia inducible factor (HIF) is essential for normal development and physiology, but this pathway may also contribute to pathological processes like tumor angiogenesis. Here we show that hypoxia is an inducer of Notch signaling. Hypoxic conditions lead to induction of the Notch ligand Dll4 and the Notch target genes Hey1 and Hey2 in various cell lines.

Relevance of the endosymbiosis of Blochmannia floridanus and carpenter ants at different stages of the life cycle of the host.

Expression of several genes possibly involved in the symbiotic relationship between the obligate intracellular endosymbiont Blochmannia floridanus and its ant host Camponotus floridanus was investigated at different developmental stages of the host by real-time quantitative PCR. These included a set of genes related to nitrogen metabolism (ureC, ureF, glnA, and speB) as well as genes involved in the synthesis of the aromatic amino acid tyrosine (tyrA, aspC, and hisC). The overall transcriptional activity of Blochmannia was found to be quite low during early developmental stages and to increase steadily with host age.

Structural and functional characterization of the zebrafish lamin B receptor.

The lamin B receptor (LBR) is an integral membrane protein of the inner nuclear membrane that is interacting with B-type lamins, chromatin and DNA. The complete loss of the protein in mouse mutants causes a reduced viability of embryos, and viable animals develop abnormalities of the skeleton. Here, we present the molecular characterization of the zebrafish LBR (zLBR) gene and the functional analysis of LBR during zebrafish embryogenesis.

Thermodynamic comparison of the interactions of cholesterol with unsaturated phospholipid and sphingomyelins.

A comparative analysis of the interaction of cholesterol (Chol) with palmitoyl-oleoyl-phosphatidylcholine (POPC) and sphingomyelins (SM) was performed in largely homogeneous, fluid-phase membranes at 50 degrees C. To this end, three independent assays for isothermal titration calorimetry were applied to POPC/SM/Chol mixtures. Cholesterol is solubilized by randomly methylated-beta-cyclodextrin and the uptake of Chol into (or release from) large unilamellar vesicles is measured.

Interaction of bacteriophage lambda with its cell surface receptor: an in vitro study of binding of the viral tail protein gpJ to LamB (Maltoporin).

The cell surface receptor for bacteriophage Lambda is LamB (maltoporin). Responsible for phage binding to LamB is the C-terminal part, gpJ, of phage tail protein J. To study the interaction between LamB and gpJ, a chimera protein composed of maltose binding protein (MBP or MalE) connected to the C-terminal part of J (gpJ, amino acids 684-1131) of phage tail protein J of bacteriophage Lambda was expressed in Escherichia coli and purified to homogeneity.

The Drosophila melanogaster LEM-domain protein MAN1.

Here we describe the Drosophila melanogaster LEM-domain protein encoded by the annotated gene CG3167 which is the putative ortholog to vertebrate MAN1. MAN1 of Drosophila (dMAN1) and vertebrates have the following properties in common. Firstly, both molecules are integral membrane proteins of the inner nuclear membrane (INM) and share the same structural organization comprising an N-terminally located LEM motif, two transmembrane domains in the middle of the molecule, and a conserved RNA recognition motif in the C-terminal region.

Reduced U snRNP assembly causes motor axon degeneration in an animal model for spinal muscular atrophy.

Spinal muscular atrophy (SMA) is a motoneuron disease caused by reduced levels of survival motoneuron (SMN) protein. Previous studies have assigned SMN to uridine-rich small nuclear ribonucleoprotein particle (U snRNP) assembly, splicing, transcription, and RNA localization. Here, we have used gene silencing to assess the effect of SMN protein deficiency on U snRNP metabolism in living cells and organisms.

The myristoylation site of meiotic lamin C2 promotes local nuclear membrane growth and the formation of intranuclear membranes in somatic cultured cells.

Lamin C2 is a splice product of the mammalian lamin A gene and expressed in primary spermatocytes where it is distributed in the form of discontinuous plaques at the nuclear envelope. We have previously shown that the aminoterminal hexapetide GNAEGR of lamin C2 following the start methionine is essential for its association with the nuclear envelope and that the aminoterminal glycine of the hexapeptide is myristoylated. Here we have analyzed the ultrastructural changes induced in COS-7 and Xenopus A6 cells by overexpressing rat lamin C2 or a human lamin C mutant possessing the lamin C2-specific hexapeptide at its aminoterminus.