Clutch mechanism of chemomechanical coupling in a DNA resecting motor nuclease Journal Article


Authors: Unciuleac, M. C.; Meir, A.; Xue, C.; Warren, G. M.; Greene, E. C.; Shuman, S.
Article Title: Clutch mechanism of chemomechanical coupling in a DNA resecting motor nuclease
Abstract: Mycobacterial AdnAB is a heterodimeric helicase.nuclease that initiates homologous recombination by resecting DNA double-strand breaks (DSBs). The N-terminal motor domain of the AdnB subunit hydrolyzes ATP to drive rapid and processive 3′ to 5′ translocation of AdnAB on the tracking DNA strand. ATP hydrolysis is mechanically productive when oscillating protein domain motions synchronized with the ATPase cycle propel the DNA tracking strand forward by a single-nucleotide step, in what is thought to entail a pawl-and-ratchet.like fashion. By gauging the effects of alanine mutations of the 16 amino acids at the AdnB.DNA interface on DNA-dependent ATP hydrolysis, DNA translocation, and DSB resection in ensemble and single-molecule assays, we gained key insights into which DNA contacts couple ATP hydrolysis to motor activity. The results implicate AdnB Trp325, which intercalates into the tracking strand and stacks on a nucleobase, as the singular essential constituent of the ratchet pawl, without which ATP hydrolysis on ssDNA is mechanically futile. Loss of Thr663 and Thr118 contacts with tracking strand phosphates and of His665 with a nucleobase drastically slows the AdnAB motor during DSB resection. Our findings for AdnAB prompt us to analogize its mechanism to that of an automobile clutch. © 2021 National Academy of Sciences. All rights reserved.
Keywords: dna repair; mycobacterium; helicase mechanism
Journal Title: Proceedings of the National Academy of Sciences of the United States of America
Volume: 118
Issue: 11
ISSN: 0027-8424
Publisher: National Academy of Sciences  
Date Published: 2021-03-16
Start Page: e2023955118
Language: English
DOI: 10.1073/pnas.2023955118
PROVIDER: scopus
PMCID: PMC7980473
PUBMED: 33836607
DOI/URL:
Notes: Article -- Export Date: 1 April 2021 -- Source: Scopus
Altmetric
Citation Impact
BMJ Impact Analytics
MSK Authors
  1. Stewart H Shuman
    546 Shuman
  2. Mihaela Carmen Sandu
    19 Sandu
  3. Garrett Mason Warren
    6 Warren