Abstract

Understanding microRNA function through biophysical investigationLara Sweetapplea, David Kosekb, Elnaz Banijamalia, Walter Beckera, Juliane Müllera, Ileana Guzzettia, Lorenzo Barontia, Emma Anderssonb & Katja Petzoldc,d a Karolinska Institutet, Department of Medical Biochemistry and Biophysics b Karolinska Institutet, Department of Cell and Molecular Biologyc Uppsala University, Department of Medical Biochemistry and Microbiology d SciLifeLab (Science for Life Laboratory) microRNAs (miRNAs) are small, non-coding RNA molecules that subtly manipulate messenger RNA (mRNA) translation or degradation. The interaction of miRNAs with their target mRNAs is guided by binding to the complementary seed region (~6 nucleotides at the miRNA 5’ end) and an imperfect base-pairing pattern outside the seed region, which can exhibit dynamic properties upon binding to its target. The human miRNA miR-34a mediates tumour suppression, and interacts with more than 100 validated mRNA targets. How a single miRNA can both select its targets specifically, and modulate a diverse network of mRNA targets, is poorly understood. Our work aims to elucidate the structural determinants beyond the seed of miR-34a:mRNA interaction to further resolve miRNA targeting function, using a selection of 12 biologically and structurally diverse miR-34a targets. Preliminary results using a combination of structural and functional methods suggest that distinct structural and biophysical properties characterise binding of the 12 targets to miR-34a. This work could aid the understanding of whether various binding modes mediate the miRNA:mRNA selection process.