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bioRxiv · 10.1101/2021.03.08.434477

A viral genome packaging ring-ATPase is a flexibly coordinated pentamer

Dai, L.·Singh, D.·Lu, S.·Kottadiel, V.·Vafabakhsh, R.·Mahalingam, M.·Chemla, Y. R.·Ha, T.·Rao, V. B.
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Abstract

Multi-subunit ring-ATPases carry out a myriad of biological functions, including genome packaging in viruses. Though the basic structures and functions of these motors have been well-established, the mechanisms of ATPase firing and motor coordination are poorly understood. Here, by direct counting using single-molecule fluorescence, we have determined that the active bacteriophage T4 DNA packaging motor consists of five subunits of gp17. By systematically doping motors with an ATPase-defective subunit and selecting single motors containing a precise count of active/inactive subunit(s), we found, unexpectedly, that the packaging motor can tolerate an inactive sub-unit. However, motors containing an inactive subunit(s) exhibit fewer DNA engagements, a higher failure rate in encapsidation, reduced packaging velocity, and increased pausing. These findings suggest a new packaging model in which the motor, by re-adjusting its grip on DNA, can skip an inactive subunit and resume DNA translocation, contrary to the prevailing notion of strict coordination amongst motor subunits of other packaging motors.

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Dai, L., Singh, D., Lu, S., Kottadiel, V., Vafabakhsh, R., Mahalingam, M., Chemla, Y. R., Ha, T., Rao, V. B.. 2021-03-09. A viral genome packaging ring-ATPase is a flexibly coordinated pentamer. https://doi.org/10.1101/2021.03.08.434477

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