Journal Article

Direction of flagellum beat propagation is controlled by proximal/distal outer dynein arm asymmetry


The 9+2 axoneme structure of the motile flagellum/cilium is an iconic, apparently symmetrical cellular structure. Recently, asymmetries along the length of motile flagella have been identified in a number of organisms, typically in the inner and outer dynein arms. Flagellum beat waveforms are adapted for different  functions.  They  may  start  either  near  the  flagellar  tip or  near  its base  (and may be  symmetrical or asymmetrical). We hypothesised that proximal/distal asymmetry in the molecular composition of the axoneme may control the site of waveform initiation and direction of waveform propagation.  The  unicellular  eukaryotic  pathogens  Trypanosoma  brucei and  Leishmania  mexicana  often switch between tip‐to‐base and base‐to‐tip waveforms, making them ideal for analysis of this phenomenon. We show here that the proximal and distal portions of the flagellum contain distinct outer dynein arm docking complex heterodimers. This proximal/distal asymmetry is produced and maintained through growth by a concentration gradient of the proximal docking complex, generated by intraflagellar transport. Furthermore, this asymmetry is involved in regulating whether a tip‐to‐base or base‐to‐tip beat occurs, which is linked to a calcium‐dependent switch. Our data show that the mechanism for generating proximal/distal flagellar asymmetry can control waveform initiation and propagation direction.

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Edwards, Beatrice Freya Lucy
Wheeler, Richard John
Barker, Amy Rachel
Fernandes Moreira-Leite, Flávia
Gull, Keith
Sunter, Jack Daniel

Oxford Brookes departments

Faculty of Health and Life Sciences\Department of Biological and Medical Sciences


Year of publication: 2018
Date of RADAR deposit: 2018-07-02

Creative Commons License This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License

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