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Plasmodium parasites possess two endosymbiotic organelles: a mitochondrion and a relict plastid called the apicoplast. To accommodate the translational requirements of these organelles in addition to its cytosolic translation apparatus, the parasite must maintain a supply of charged tRNA molecules in each of these compartments. In the present study we investigate how the parasite manages these translational requirements for charged tRNACys with only a single gene for CysRS (cysteinyltRNA synthetase). We demonstrate that the single Pf CysRS (Plasmodium falciparum CysRS) transcript is alternatively spliced, and, using a combination of endogenous and heterologous tagging experiments in both P. falciparum and Toxoplasma gondii, we show that CysRS isoforms traffic to the cytosol and apicoplast. Pf CysRS can recognize and charge the eukaryotic tRNACys encoded by the Plasmodium nucleus as well as the bacterial-type tRNA encoded by the apicoplast genome, albeit with a preference for the eukaryotic type cytosolic tRNA. The results of the present study indicate that apicomplexan parasites have lost their original plastidic cysteinyl-tRNA synthetase, and have replaced it with a dual-targeted eukaryotic type CysRS that recognizes plastid and nuclear tRNACys. Inhibitors of the Plasmodium dual-targeted CysRS would potentially offer a therapy capable of the desirable immediate effects on parasite growth as well as the irreversibility of inhibitors that disrupt apicoplast inheritance. [ABSTRACT FROM AUTHOR]

Plasmodium parasites possess two endosymbiotic organelles: a mitochondrion and a relict plastid called the apicoplast. To accommodate the translational requirements of these organelles in addition to its cytosolic translation apparatus, the parasite must maintain a supply of charged tRNA molecules in each of these compartments. In the present study we investigate how the parasite manages these translational requirements for charged tRNACys with only a single gene for CysRS (cysteinyltRNA synthetase). We demonstrate that the single Pf CysRS (Plasmodium falciparum CysRS) transcript is alternatively spliced, and, using a combination of endogenous and heterologous tagging experiments in both P. falciparum and Toxoplasma gondii, we show that CysRS isoforms traffic to the cytosol and apicoplast. Pf CysRS can recognize and charge the eukaryotic tRNACys encoded by the Plasmodium nucleus as well as the bacterial-type tRNA encoded by the apicoplast genome, albeit with a preference for the eukaryotic type cytosolic tRNA. The results of the present study indicate that apicomplexan parasites have lost their original plastidic cysteinyl-tRNA synthetase, and have replaced it with a dual-targeted eukaryotic type CysRS that recognizes plastid and nuclear tRNACys. Inhibitors of the Plasmodium dual-targeted CysRS would potentially offer a therapy capable of the desirable immediate effects on parasite growth as well as the irreversibility of inhibitors that disrupt apicoplast inheritance. [ABSTRACT FROM AUTHOR]

The NF-κB signal transduction pathway has crucial functions in cell growth, survival, and the development of lymphocytes and other immune cells. Upon activation of the pathway, five distinct NF-κB transcription factor subunits that occur as homodimers or heterodimers comprise the downstream mediators that transcribe NF-κB target genes. A major quest in NF-κB research is to understand the biology of the separate subunits. However, determining the functions of the individual subunits using constitutional knockout mice is often hampered by the marked cell type and/or developmental stage-specific activation of the NF-κB pathway. To overcome these problems, we and others have generated loxP-flanked alleles of the genes encoding the different NF-κB subunits that upon crossing to suitable Cre-expressing mouse lines can be conditionally deleted in the desired cell type or developmental stage. We here describe the basic characteristics of conditional NF-κB subunit alleles rel (encoding c-REL), rela (RELA), relb (RELB), and nfkb2 (NF-κB2) generated in our laboratory that are available to the research community through a repository, and provide basic methods to study the consequences of tissue-specific ablation of NF-κB transcription factors in lymphocytes.