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Pabbathi A, Coleman L, Godar S, Paul A, Garlapati A, Spencer M, Eller J, Alper JD. Long-range electrostatic interactions significantly modulate the affinity of dynein for microtubules. Biophys J 2022; 121:1715-1726. [PMID: 35346642 PMCID: PMC9117880 DOI: 10.1016/j.bpj.2022.03.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 01/13/2022] [Accepted: 03/24/2022] [Indexed: 11/02/2022] Open
Abstract
The dynein family of microtubule minus-end-directed motor proteins drives diverse functions in eukaryotic cells, including cell division, intracellular transport, and flagellar beating. Motor protein processivity, which characterizes how far a motor walks before detaching from its filament, depends on the interaction between its microtubule-binding domain (MTBD) and the microtubule. Dynein's MTBD switches between high- and low-binding affinity states as it steps. Significant structural and functional data show that specific salt bridges within the MTBD and between the MTBD and the microtubule govern these affinity state shifts. However, recent computational work suggests that nonspecific, long-range electrostatic interactions between the MTBD and the microtubule may also play an important role in the processivity of dynein. To investigate this hypothesis, we mutated negatively charged amino acids remote from the dynein MTBD-microtubule-binding interface to neutral residues and measured the binding affinity using microscale thermophoresis and optical tweezers. We found a significant increase in the binding affinity of the mutated MTBDs for microtubules. Furthermore, we found that charge screening by free ions in solution differentially affected the binding and unbinding rates of MTBDs to microtubules. Together, these results demonstrate a significant role for long-range electrostatic interactions in regulating dynein-microtubule affinity. Moreover, these results provide insight into the principles that potentially underlie the biophysical differences between molecular motors with various processivities and protein-protein interactions more generally.
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Affiliation(s)
- Ashok Pabbathi
- Department of Physics and Astronomy, Clemson University, Clemson, South Carolina
| | - Lawrence Coleman
- Department of Physics and Astronomy, Clemson University, Clemson, South Carolina
| | - Subash Godar
- Department of Physics and Astronomy, Clemson University, Clemson, South Carolina
| | - Apurba Paul
- Department of Physics and Astronomy, Clemson University, Clemson, South Carolina; Eukaryotic Pathogen Innovations Center, Clemson, University, Clemson, South Carolina
| | - Aman Garlapati
- School of Mathematical and Statistical Sciences, Clemson University, Clemson, South Carolina
| | - Matheu Spencer
- Department of Physics and Astronomy, Clemson University, Clemson, South Carolina
| | - Jared Eller
- Department of Physics and Astronomy, Clemson University, Clemson, South Carolina; Department of Genetics and Biochemistry, Clemson University, Clemson, South Carolina
| | - Joshua Daniel Alper
- Department of Physics and Astronomy, Clemson University, Clemson, South Carolina; Eukaryotic Pathogen Innovations Center, Clemson, University, Clemson, South Carolina; Department of Biological Sciences, Clemson University, Clemson, South Carolina.
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