A high-affinity ATP-binding site on 30S dynein

Area of Science:

• Biochemistry
• Molecular Biology
• Cell Biology

Background:

• 30S dynein is a crucial motor protein involved in cellular transport.
• Understanding the regulation of dynein ATPase activity is essential for elucidating its functions.

Purpose of the Study:

• To investigate the effect of bis(4-fluoro-3-nitrophenyl)sulfone (FNS) and dithiothreitol (DTT) on 30S dynein ATPase activity.
• To characterize the binding properties of ATP to 30S dynein.

Main Methods:

• Enzyme kinetics assays were performed to measure 30S dynein ATPase activity.
• The effects of varying concentrations of FNS, DTT, ATP, and ATP analogs (AMP-PNP, AMP-PCP) were analyzed.
• pH dependence of the FNS + DTT effect was determined.

Main Results:

• Low concentrations of FNS (8 microM) significantly enhanced 30S dynein ATPase activity in the presence of 1 mM DTT.
• The FNS + DTT-mediated enhancement was optimal at pH 7.5.
• The activation was partially inhibited by 1-3 microM ATP, indicating a high-affinity ATP-binding site.
• ATP analogs showed differential effects: AMP-PNP was less effective than ATP, and AMP-PCP did not prevent enhancement despite being a strong ATPase inhibitor.

Conclusions:

• Bis(4-fluoro-3-nitrophenyl)sulfone (FNS) and dithiothreitol (DTT) act synergistically to activate latent 30S dynein ATPase activity.
• The results strongly support the existence of a high-affinity ATP-binding site on 30S dynein, crucial for its motor function.
• This study provides insights into the regulatory mechanisms of dynein motor proteins.