Flagellar and ciliary beating: the proven and the possible.

Area of Science:

• Cell Biology
• Biophysics
• Molecular Motors

Background:

• The precise mechanism of eukaryotic flagellar axoneme beating, particularly the coordination of dynein motor proteins, remains a significant challenge in cell biology.
• While the basic mechanical operation of the axoneme is understood, the regulatory processes governing dynein activity are still debated.

Purpose of the Study:

• To review and synthesize recent experimental findings that shed light on the elusive dynein switching mechanism.
• To discuss how new evidence regarding inner dynein arms, microtubule binding affinity, and bending influences hypotheses of axonemal dynein coordination.

Main Methods:

• This commentary synthesizes findings from recent experimental reports.
• It analyzes evidence in the context of existing hypotheses on axonemal dynein coordination.

Main Results:

• Recent evidence implicates the specific role of inner dynein arms (IDAs), particularly dynein I1 and the dynein regulatory complex.
• The importance of dynein microtubule-binding affinity at the stalk has been highlighted.
• The role of flagellar bending in selecting active dynein groups is supported by new data.

Conclusions:

• New experimental evidence provides critical insights into the coordination of dynein motors within the axoneme.
• Further research integrating the roles of inner dynein arms, microtubule binding, and bending is crucial for fully understanding flagellar beating.
• This synthesis offers a framework for future investigations into this fundamental biological process.