skip to main content

DOE PAGESDOE PAGES

Title: Two-subunit DNA escort mechanism and inactive subunit bypass in an ultra-fast ring ATPase

SpoIIIE is a homo-hexameric dsDNA translocase responsible for completing chromosome segregation in Bacillus subtilis. Here in this study, we use a single-molecule approach to monitor SpoIIIE translocation when challenged with neutral-backbone DNA and non-hydrolyzable ATP analogs. We show that SpoIIIE makes multiple essential contacts with phosphates on the 5'→3' strand in the direction of translocation. Using DNA constructs with two neutral-backbone segments separated by a single charged base pair, we deduce that SpoIIIE’s step size is 2 bp. Finally, experiments with non-hydrolyzable ATP analogs suggest that SpoIIIE can operate with non-consecutive inactive subunits. We propose a two-subunit escort translocation mechanism that is strict enough to enable SpoIIIE to track one DNA strand, yet sufficiently compliant to permit the motor to bypass inactive subunits without arrest. We speculate that such a flexible mechanism arose for motors that, like SpoIIIE, constitute functional bottlenecks where the inactivation of even a single motor can be lethal for the cell.
Authors:
 [1] ;  [2] ;  [3]
  1. Univ. of California, Berkeley, CA (United States). Jason L. Choy Laboratory of Single Molecule Biophysics; Univ. of California, Berkeley, CA (United States). Dept. of Molecular and Cell Biology
  2. Univ. of California, Berkeley, CA (United States). Jason L. Choy Laboratory of Single Molecule Biophysics; Univ. of California, Berkeley, CA (United States). Dept. of Physics
  3. Univ. of California, Berkeley, CA (United States). Jason L. Choy Laboratory of Single Molecule Biophysics; Univ. of California, Berkeley, CA (United States). Dept. of Molecular and Cell Biology; Univ. of California, Berkeley, CA (United States). Dept. of Physics; California Inst. for Quantitative Biosciences, Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States). Howard Hughes Medical Inst., Dept. of Chemistry; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Physical Biosciences Division; Univ. of California, Berkeley, CA (United States). Kavli Energy NanoSciences Inst.; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Publication Date:
Grant/Contract Number:
AC02-05CH11231; R01GM071552; R01GM032543
Type:
Accepted Manuscript
Journal Name:
eLife
Additional Journal Information:
Journal Volume: 4; Journal ID: ISSN 2050-084X
Publisher:
eLife Sciences Publications, Ltd.
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Institutes of Health (NIH)
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES
OSTI Identifier:
1415944