Dipankar Sen
Simon Fraser University, Canada
Title: Fishing for G-quadruplexes and G-quadruplex proximal proteins by virtue of the peroxidase properties
Biography
Biography: Dipankar Sen
Abstract
The powerful in vitro affinity observed between the ubiquitous cellular cofactor, hemin, and DNA or RNA G-quadruplexes, raises the intriguing possibility that this interaction also occurs in vivo. A further, intriguing possibility is that this affinity, and the notable peroxidase activity of the resulting G-quadruplex•hemin complexes, could be used to tag G-quadruplexes (and G-quadruplex-interacting and -proximal proteins) within living cells. Such investigations are in principle enabled by our long-time observation that hemin•G-quadruplex complexes are strongly enabled towards catalysis of 1- and 2-electron oxidative reactions, with phenolic compounds being especially outstanding substrates. We have recently reported that the use of biotinyl tyramide as a substrate for G-quadruplex•hemin peroxidases in vitro leads to the self-biotinylation of the G-quadruplexes themselves. Such self-biotinylation occurs with good efficiency and high discrimination, being entirely specific for G-quadruplexes and not, for instance, DNA duplexes. Furthermore, DNA biotinylated in this way remains amenable to polymerase chain reaction amplification, rendering it suitable for analysis by ChIP-Seq and related methodologies. We will present new data on this self-biotinylation methodology, that we anticipate will serve as a sensitive tool, orthogonal to existing ones, for identifying, labeling and pulling down cellular RNA and DNA G-quadruplexes as well as proteins either bound to or proximal to such quadruplexes.