 In this Issue, N. Budisa and co-workers discuss the use of blue fluorescent amino acids as in vivo protein building blocks. They have identified methylated chromophores based on 4- and 7-azaindole that have the potential to provide proteins with intrinsic blue or green fluorescence (see picture). In a highlight, I. Weiss covers the recent discovery of the aragonite-specific protein complex of Pif97 and Pif80; this discovery provides new views on remote control of nacre formation, will open fundamentally new ways of studying the fine-tuning of shells, and will have major implications
for understanding the evolution of controlled biomineralization. W. E. Georgianna and A. Deiters highlight reversible light switching of cell signalling by using genetically encoded protein dimerization. A genetically encoded system based on the photoswitchable Arabidopsis thaliana PhyB–PIF interaction has been applied to the reversible photocontrol of protein translocation and cellular morphology in mammalian cells. In the original research section, W. J. Hagan Jr. describes the uracil-catalyzed photochemical synthesis of the metabolite acetyl phosphate in a full paper. This compound may have served at the core of the earliest energy-storage networks, and thus could be a missing link to the RNA World. Finally, F. Boán and J. Gómez-Márquez examine in vitro recombination mediated by the G-quadruplex. In the annealing step of the first PCR cycles, some DNA molecules acquire the G4 structure. These G-quadruplexes intermingle to form a bimolecular quadruplex that could allow the nascent DNA to cross to another strand during extension and generate a recombinant molecule. Browse Issue 3/2010 now.
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