Fluorescent nanodiamonds for FRET-based monitoring of a single biological nanomotor FoF1-ATP synthase

TL;DR

This paper introduces the use of fluorescent nanodiamonds as stable, photostable markers for FRET-based monitoring of the rotary motion of the biological nanomotor FoF1-ATP synthase, enabling long-term single-molecule studies.

Contribution

It demonstrates the application of fluorescent nanodiamonds for extended FRET measurements of enzyme rotation, surpassing limitations of traditional fluorophores.

Findings

Nanodiamonds enable long-term FRET monitoring.

They reveal detailed rotary motion of ATP synthase.

Enhanced stability improves single-molecule tracking.

Abstract

Color centers in diamond nanocrystals are a new class of fluorescence markers that attract significant interest due to matchless brightness, photostability and biochemical inertness. Fluorescing diamond nanocrystals containing defects can be used as markers replacing conventional organic dye molecules, quantum dots or autofluorescent proteins. They can be applied for tracking and ultrahigh-resolution localization of the single markers. In addition the spin properties of diamond defects can be utilized for novel magneto-optical imaging (MOI) with nanometer resolution. We develop this technique to unravel the details of the rotary motions and the elastic energy storage mechanism of a single biological nanomotor FoF1-ATP synthase. FoF1-ATP synthase is the enzyme that provides the 'chemical energy currency' adenosine triphosphate, ATP, for living cells. The formation of ATP is accomplished by a stepwise internal rotation of subunits within the enzyme. Previously subunit rotation has been monitored by single-molecule fluorescence resonance energy transfer (FRET) and was limited by the photostability of the fluorophores. Fluorescent nanodiamonds advance these FRET measurements to long time scales.