CCB Colloquium – Professor Keith Mickolajczyk, RWJ Medical School

Single-molecule biophysical approaches to studying the mechanisms of motor proteins

Ribosomes are molecular machines made of protein and RNA that translate mRNA into proteins. The biogenesis of new ribosomes is the most energetically costly process in the cell, accounting for ~60% of all ATP consumed. New ribosomes begin as rRNA, and are sequentially matured through a complicated multi-step process that involves hundreds of protein factors, including motor proteins (force-producing enzymes) from the AAA (ATPase associated with diverse cellular activities) and helicase-2 (SF2) superfamilies. Dysregulation of ribosome biogenesis is linked to genetic diseases (ribosomopathies), and its upregulation is a hallmark of proliferative cancers. Nonetheless, the molecular mechanisms underlying ribosome maturation – how motor proteins sequentially convert ribosomal precursors into mature particles – remain poorly understood. Filling this gap in knowledge is essential for understanding ribosomal biology in health and disease, and for exploring new classes of ribosome biogenesis-targeting chemotherapeutics.

In the Mickolajczyk Lab we develop and apply state-of-the-art single-molecule biophysical techniques including optical tweezers, magnetic tweezers, FRET, and label-free imaging to study how AAA and SF2 motor proteins drive ribosome biogenesis. We directly measure how these motors convert the energy from ATP hydrolysis into mechanical work, and how those forces are then used to change the structure and composition of ribosomal precursors. We further explore how disease-causing mutations in ribosomal proteins alter this fundamental enzymology, with the ultimate goal of guiding new molecular therapies for ribosomopathies and proliferative cancers.