In PNAS this week, an international research team reports that DNp73, the transactivation-deficient, antiapoptotic form of p73, is degraded in a c-Jun-controlled manner upon genotoxic stress through the antizyme-mediated pathway. In investigating the potential mechanisms for stress-induced DNp73 degradation, the team found that the absence or down-regulation of c-Jun expression "abrogated the reduction of DNp73 levels upon stress insults, whereas overexpression of c-Jun led to its degradation." Expression of antizyme also promotes DNp73 degradation, the team writes, adding that Az was also able to bind DNp73.
Researchers in France this week describe the expression of the full-length var2CSA extracellular region in parasitized erythrocytes. They show the extracellular region of var2CSA, a variant of PfEMP1, is required for specific, high-affinity binding to chondroitin sulfate A present on placental proteoglycans. Because "recent work implicates var2CSA…as the mediator of placental sequestration and as a key target for PAM [pregnancy-associated malaria] vaccine development," the authors suggest their "results have important consequences for the development of an effective vaccine and therapeutic inhibitors."
In the PNAS Early Edition this week, a trio of investigators from Duke University report that topoisomerase IIIα is required for the maintenance of mitochondrial genome and male germ-line stem cells in Drosophila melanogaster. The team writes that both the short- and long-forms of topo IIIα can rescue the viability of null mutants of top3a, the gene that encodes them. "No apparent defect is associated with the flies rescued by the long form; short-form-rescued flies (referred to as M1L), however, exhibit defects in fertilities. M1L females are sterile," the team writes, suggesting that topo IIIα is a causative candidate for genetic disorders associated with the depletion of mtDNA.
Also in the Early Edition, researchers at the Max Planck Institute for Molecular Plant Physiology present their use of bacterial riboswitches, modified in silico, to induce gene expression in plastids. "We report the identification of a synthetic riboswitch that functions as an efficient translational regulator of gene expression in plastids in response to its exogenously applied ligand theophyllin," they write, adding their position that the riboswitch functions as a novel tool for plastid genome engineering that can be widely applied throughout functional genomics and biotechnology.