Insights on viral DNA packaging motor mechanisms from the effects of motor residue changes on single-molecule packaging dynamics
Abstract
Many dsDNA viruses utilize a molecular motor to translocate DNA into preassembled viral prohead shells. We apply methods we have developed for measuring the dynamics of single DNA molecule packaging with optical tweezers to study the mechanism of the bacteriophage lambda motor. In collaboration with the groups of Michael Feiss and Carlos Catalano we used site-directed mutagenesis to investigate the roles of various motor protein residues in translocation function. We found that residue changes in the proposed Walker A and Walker B ATP binding motif and catalytic glutamate cause varying impairments, ranging from partial impairment to total abrogation of DNA translocation activity. Altogether, we studied 23 mutants and identified 11 with no detectable translocation and 12 having varying impairments. The results support the proposed motif assignments and observed changes in motor velocity and pausing and slipping dynamics for the partly impaired mutants give insights on residues involved in ATP binding and positioning, coupling between ATP binding and DNA gripping, and catalysis of hydrolysis.
NIH Grants R01GM088186 and R01GM118817.- Publication:
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APS March Meeting Abstracts
- Pub Date:
- 2018
- Bibcode:
- 2018APS..MARP50005O