Search results for "recte"
showing 10 items of 463 documents
The soluble loop BC region guides, but not dictates, the assembly of the transmembrane cytochrome b6
2017
Studying folding and assembly of naturally occurring α-helical transmembrane proteins can inspire the design of membrane proteins with defined functions. Thus far, most studies have focused on the role of membrane-integrated protein regions. However, to fully understand folding pathways and stabilization of α–helical membrane proteins, it is vital to also include the role of soluble loops. We have analyzed the impact of interhelical loops on folding, assembly and stability of the heme-containing four-helix bundle transmembrane protein cytochrome b6 that is involved in charge transfer across biomembranes. Cytochrome b6 consists of two transmembrane helical hairpins that sandwich two heme mol…
G protein-coupled odorant receptors underlie mechanosensitivity in mammalian olfactory sensory neurons
2014
Mechanosensitive cells are essential for organisms to sense the external and internal environments, and a variety of molecules have been implicated as mechanical sensors. Here we report that odorant receptors (ORs), a large family of G protein-coupled receptors, underlie the responses to both chemical and mechanical stimuli in mouse olfactory sensory neurons (OSNs). Genetic ablation of key signaling proteins in odor transduction or disruption of OR–G protein coupling eliminates mechanical responses. Curiously, OSNs expressing different OR types display significantly different responses to mechanical stimuli. Genetic swap of putatively mechanosensitive ORs abolishes or reduces mechanical res…
Mutations in the rpoB and katG Genes Leading to Drug Resistance in Mycobacterium tuberculosis in Latvia
2002
ABSTRACT To characterize the genetic basis of drug resistance in Mycobacterium tuberculosis in Latvia, mutations involved in rifampin ( rpoB gene) and isoniazid ( katG gene) resistance in DNA from 19 drug-susceptible and 51 multidrug-resistant M. tuberculosis complex isolates were analyzed. The most frequent rpoB gene mutations found by the Line Probe assay were the S531L (14 of 34 isolates), D516V (7 of 34), H526D (4 of 34), and D516Y plus P535S (4 of 34) mutations. Direct sequencing of seven isolates with unclear results from Line Probe assay showed the presence of the L533P mutation and the Q510H plus H526Y (1 of 34) and D516V plus P535S (4 of 34) double mutations, neither of which has b…
Incidence, Diversity, and Molecular Epidemiology of Sapoviruses in Swine across Europe▿
2010
ABSTRACT Porcine sapovirus is an enteric calicivirus in domestic pigs that belongs to the family Caliciviridae . Some porcine sapoviruses are genetically related to human caliciviruses, which has raised public health concerns over animal reservoirs and the potential cross-species transmission of sapoviruses. We report on the incidence, genetic diversity, and molecular epidemiology of sapoviruses detected in domestic pigs in a comprehensive study conducted in six European countries (Denmark, Finland, Hungary, Italy, Slovenia, and Spain) between 2004 and 2007. A total of 1,050 swine fecal samples from 88 pig farms were collected and tested by reverse transcription-PCR for sapoviruses, and pos…
Substrate pathways and mechanisms of inhibition in the sulfur oxygenase reductase of Acidianus ambivalens
2011
Background: The sulfur oxygenase reductase (SOR) is the initial enzyme of the sulfur oxidation pathway in the thermoacidophilic Archaeon Acidianus ambivalens. The SOR catalyzes an oxygen-dependent sulfur disproportionation to H2S, sulfite and thiosulfate. The spherical, hollow, cytoplasmic enzyme is composed of 24 identical subunits with an active site pocket each comprising a mononuclear non-heme iron site and a cysteine persulfide. Substrate access and product exit occur via apolar chimney-like protrusions at the four-fold symmetry axes, via narrow polar pores at the three-fold symmetry axes and via narrow apolar pores within in each subunit. In order to investigate the function of the po…
Social evolution of innate immunity evasion in a virus
2019
Antiviral immunity has been studied extensively from the perspective of virus−cell interactions, yet the role of virus−virus interactions remains poorly addressed. Here, we demonstrate that viral escape from interferon (IFN)-based innate immunity is a social process in which IFN-stimulating viruses determine the fitness of neighbouring viruses. We propose a general and simple social evolution framework to analyse how natural selection acts on IFN shutdown and validate it in cell cultures and mice infected with vesicular stomatitis virus. Furthermore, we find that IFN shutdown is costly because it reduces short-term viral progeny production, thus fulfilling the definition of an altruistic tr…
Molecular Epidemiology of Caliciviruses Causing Outbreaks and Sporadic Cases of Acute Gastroenteritis in Spain
2002
ABSTRACT The molecular epidemiology of human caliciviruses (HuCVs) causing sporadic cases and outbreaks of acute gastroenteritis around eastern Spain (Catalonia and the Valencian Community) was studied by reverse transcription-PCR (RT-PCR) and by sequencing part of the RNA polymerase gene in open reading frame 1. HuCVs were detected in 44 of 310 stool specimens (14.19%) negative for other enteric pathogens obtained from children with acute gastroenteritis. Norwalk-like viruses (NLVs) were the most common cause of the gastroenteritis outbreaks investigated here. They were detected in 14 out of 25 (56%) outbreaks with an identified pathogen. Genotypes producing both sporadic cases and outbrea…
Mitochondrial interference by anti-HIV drugs: mechanisms beyond Pol-γ inhibition.
2011
The combined pharmacological approach to the treatment of HIV infection, known as highly active antiretroviral therapy (HAART), has dramatically reduced AIDS-related morbidity and mortality. However, its use has been associated with serious adverse reactions, of which those resulting from mitochondrial dysfunction are particularly widespread. Nucleos(t)ide-reverse transcriptase inhibitors (NRTIs) have long been considered the main source of HAART-related mitochondrial toxicity due to their ability to inhibit Pol-γ, the DNA polymerase responsible for the synthesis of mitochondrial DNA. Nevertheless, accumulating evidence points to a more complex relationship between these organelles and NRTI…
Structure of Rhodococcus erythropolis limonene-1,2-epoxide hydrolase reveals a novel active site
2003
Epoxide hydrolases are essential for the processing of epoxide-containing compounds in detoxification or metabolism. The classic epoxide hydrolases have an alpha/beta hydrolase fold and act via a two-step reaction mechanism including an enzyme-substrate intermediate. We report here the structure of the limonene-1,2-epoxide hydrolase from Rhodococcus erythropolis, solved using single-wavelength anomalous dispersion from a selenomethionine-substituted protein and refined at 1.2 A resolution. This enzyme represents a completely different structure and a novel one-step mechanism. The fold features a highly curved six-stranded mixed beta-sheet, with four alpha-helices packed onto it to create a …
Determination of enrichment factors for modified RNA in MeRIP experiments
2019
In the growing field of RNA modification, precipitation techniques using antibodies play an important role. However, little is known about their specificities and protocols are missing to assess their effectiveness. Here we present a method to assess enrichment factors after MeRIP-type pulldown experiments, here exemplified with a commercial antibody against N6-methyladenosine (m6A). Testing different pulldown and elution conditions, we measure enrichment factors of 4-5 using m6A-containing mRNAs against an unmodified control of identical sequence. Both types of mRNA carry 32P labels at different nucleotides, allowing their relative quantification in a mixture after digestion to nucleotides…