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Imaging biological processes in mammalian tissues will be facilitated by fluorescent probes with excitation and emission bands within the near-infrared optical window of high transparency. Here we report a phytochrome-based near-infrared fluorescent protein (iRFP) with excitation and emission maxima at 690 nm and 713 nm, respectively. iRFP does not require(More)
We report a photoswitchable monomeric Orange (PSmOrange) protein that is initially orange (excitation, 548 nm; emission, 565 nm) but becomes far-red (excitation, 636 nm; emission, 662 nm) after irradiation with blue-green light. Compared to its parental orange proteins, PSmOrange has greater brightness, faster maturation, higher photoconversion contrast and(More)
BACKGROUND The morbidity and mortality associated with malaria are heightened because of the spread of drug-resistant parasites and the lack of an effective vaccine. Plasmodium liver stages are the targets of new chemotherapeutics and vaccines, but there are limited tools available to study this stage in vivo. METHODS To overcome this obstacle, we(More)
Malaria continues to devastate sub-Saharan Africa owing to the emergence of drug resistance to established antimalarials and to the lack of an efficacious vaccine. Plasmodium species have a unique streamlined purine pathway in which the dual specificity enzyme purine nucleoside phosphorylase (PNP) functions in both purine recycling and purine salvage. To(More)
In humans and in mice, control of the intracellular pathogen, Mycobacterium tuberculosis (Mtb), requires IFN-gamma. Although the adaptive immune response results in production of substantial amounts of IFN-gamma in response to Mtb, the immune response is unable to eradicate the infection in most cases. We have previously reported evidence that Mtb inhibits(More)
The authors report the isolation and molecular characterization of a bacteriophage, φCPG1, which infects CHLAMYDIA: psittaci strain Guinea pig Inclusion Conjunctivitis. Purified virion preparations contained isometric particles of 25 nm diameter, superficially similar to spike-less members of the φX174 family of bacteriophages. The single-stranded(More)
The chlamydial life cycle involves the intimate interaction of components of the infectious elementary body (EB) surface with receptors on the susceptible eukaryotic cell plasma membrane. We have developed an in vitro ligand binding assay system for the identification and characterization of detergent-extracted EB envelope proteins capable of binding to(More)
The sexual cycle of Plasmodium is required for transmission of malaria from mosquitoes to mammals, but how parasites induce the expression of genes required for the sexual stages is not known. We disrupted the Plasmodium yoelii gene encoding high mobility group nuclear factor hmgb2, which encodes a DNA-binding protein potentially implicated in(More)
Human malaria infections resulting from Plasmodium falciparum have become increasingly difficult to treat due to the emergence of drug-resistant parasites. The P. falciparum purine salvage enzyme purine nucleoside phosphorylase (PfPNP) is a potential drug target. Previous studies, in which PfPNP was targeted by transition state analogue inhibitors, found(More)
Purine nucleoside phosphorylase from Plasmodium falciparum (PfPNP) is an anti-malarial target based on the activity of Immucillins. The crystal structure of PfPNP.Immucillin-H (ImmH).SO(4) reveals a homohexamer with ImmH and SO(4) bound at each catalytic site. A solvent-filled cavity close to the 5'-hydroxyl group of ImmH suggested that PfPNP can accept(More)