Unknown

Dataset Information

0

The dynamic pause-unpackaging state, an off-translocation recovery state of a DNA packaging motor from bacteriophage T4.


ABSTRACT: Tailed bacteriophages and herpes viruses use powerful ATP-driven molecular motors to translocate their viral genomes into a preformed capsid shell. The bacteriophage T4 motor, a pentamer of the large terminase protein (gp17) assembled at the portal vertex of the prohead, is the fastest and most powerful known, consistent with the need to package a ~170-kb viral genome in approximately 5 min. Although much is known about the mechanism of DNA translocation, very little is known about how ATP modulates motor-DNA interactions. Here, we report single-molecule measurements of the phage T4 gp17 motor by using dual-trap optical tweezers under different conditions of perturbation. Unexpectedly, the motor pauses randomly when ATP is limiting, for an average of 1 s, and then resumes translocation. During pausing, DNA is unpackaged, a phenomenon so far observed only in T4, where some of the packaged DNA is slowly released. We propose that the motor pauses whenever it encounters a subunit in the apo state with the DNA bound weakly and incorrectly. Pausing allows the subunit to capture ATP, whereas unpackaging allows scanning of DNA until a correct registry is established. Thus, the "pause-unpackaging" state is an off-translocation recovery state wherein the motor, sometimes by taking a few steps backward, can bypass the impediments encountered along the translocation path. These results lead to a four-state mechanochemical model that provides insights into the mechanisms of translocation of an intricately branched concatemeric viral genome.

PROVIDER: S-EPMC3523870 | BioStudies | 2012-01-01T00:00:00Z

REPOSITORIES: biostudies

Similar Datasets

2020-01-01 | S-EPMC7672480 | BioStudies
2009-01-01 | S-EPMC2782041 | BioStudies
2014-01-01 | S-EPMC4157569 | BioStudies
2012-01-01 | S-EPMC3318623 | BioStudies
2011-01-01 | S-EPMC3074133 | BioStudies
2011-01-01 | S-EPMC3030395 | BioStudies
2014-01-01 | S-EPMC4376518 | BioStudies
2013-01-01 | S-EPMC3903156 | BioStudies
1000-01-01 | S-EPMC5737356 | BioStudies
| S-EPMC3227225 | BioStudies