Insights into dynein motor domain function from a 3.3-Å crystal structure

Area of Science:

• Molecular Biology
• Biochemistry
• Cell Biology

Background:

• Dyneins are essential motor proteins involved in ciliary/flagellar beating, intracellular transport, and mitosis.
• The dynein motor domain comprises a six-ring AAA+ structure crucial for force generation via ATP hydrolysis.
• The precise interaction of the linker domain with the AAA+ ring during ATP hydrolysis remains uncharacterized.

Purpose of the Study:

• To elucidate the structural basis of dynein motor function.
• To understand the interaction between the dynein linker and AAA+ ring during the ATP hydrolysis cycle.
• To investigate nucleotide binding and conformational states of the dynein motor domain.

Main Methods:

• X-ray crystallography of Saccharomyces cerevisiae cytoplasmic dynein motor domain.
• Site-directed mutagenesis to confirm functional importance of identified interaction sites.
• Nucleotide soaking experiments to analyze ATP binding and conformations.

Main Results:

• A 3.3-Å crystal structure of the dynein motor domain was determined in the absence of nucleotides.
• The linker domain was observed docked to a conserved site on the AAA5 domain, confirmed as functionally essential via mutagenesis.
• Nucleotide soaking revealed AAA1 in a low-affinity conformation and characterized nucleotide interactions at AAA2, AAA3, and AAA4.

Conclusions:

• The study provides a structural framework for understanding dynein's mechanical cycle.
• The interaction of the linker with AAA5 is critical for dynein motor function.
• Distinct nucleotide-binding states of the AAA+ ring are revealed, offering insights into force generation mechanisms.