ATP consumption of eukaryotic flagella measured at a single-cell level

TL;DR

This study introduces a novel single-cell method to measure ATP consumption in actively beating eukaryotic flagella, revealing how beating frequency and viscosity influence energy use, advancing understanding of flagellar motility.

Contribution

The paper presents a new experimental approach to quantify ATP consumption in single-cell flagella, linking energy use to beating frequency and waveform changes.

Findings

ATP consumption rate linearly correlates with beating frequency

Approximately 2.3e5 ATP molecules are used per beat

Higher viscosity increases energy consumption per beat

Abstract

The motility of cilia and flagella is driven by thousands of dynein motors that hydrolyze adenosine triphosphate (ATP). Despite decades of genetic, biochemical, structural and biophysical studies, some aspects of ciliary motility remain elusive, such as the regulation of beating patterns and the energetic efficiency of these nanomachines. Here, we introduce an experimental method to measure ATP consumption of actively beating axonemes on a single-cell level. We encapsulated individual sea urchin sperm with demembranated flagellum inside water-in-oil emulsion droplets and measured the axonemes ATP consumption by monitoring fluorescence intensity of a fluorophore-coupled reporter system for ATP turnover in the droplet. Concomitant phase contrast imaging allowed us to extract a linear dependence between the ATP consumption rate and the flagellar beating frequency, with ~2.3e5 ATP molecules consumed per beat of a demembranated flagellum. Increasing the viscosity of the aqueous medium led to modified beating waveforms of the axonemes and to higher energy consumption per beat cycle. Our single-cell experimental platform provides both new insights into the beating mechanism of flagella and a powerful tool for future studies.