Guanine-rich sequences of DNA and RNA fold into quadruplexes when four guanine bases form tetrads stabilized by Hoogsteen hydrogen bonds. Quadruplexes can be uni-,bi-, or tetra-molecular structures depending on the number of nucleic acid strands involved, and are stabilized by potassium cations. Previous studies have shown that DNA G-quadruplexes have potential to form in telomeres in the human genome as well as the promoters of oncogenes, but little is known about quadruplex formation in prokaryotic genomes. The Gram-negative proteobacterium <i>Bdellovibrio bacteriovorus</i> contains ~20 guanine-rich potential quadruplex forming sequences; we are examining the structures, kinetics, and thermodynamics of three in detail to determine whether they might indeed form quadruplexes under <i>in vivo</i> conditions. Using CD and fluorescence spectroscopy, we have clearly demonstrated that indeed all three form quadruplexes robustly, but quadruplex formation depends critically on cellular parameters including molecular crowding, folding time, and presence of the complementary strand, all of which may reduce the likelihood of formation in bacterial cells.

Bacterial nucleic acid quadruplex formation

256th National Meeting (2018)

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