Skip to main content
construction release_alert
Scholars@Duke will be undergoing maintenance April 11-15. Some features may be unavailable during this time.
cancel
Journal cover image

Interplay of catalysis, fidelity, threading, and processivity in the exo- and endonucleolytic reactions of human exonuclease I.

Publication ,  Journal Article
Shi, Y; Hellinga, HW; Beese, LS
Published in: Proc Natl Acad Sci U S A
June 6, 2017

Human exonuclease 1 (hExo1) is a member of the RAD2/XPG structure-specific 5'-nuclease superfamily. Its dominant, processive 5'-3' exonuclease and secondary 5'-flap endonuclease activities participate in various DNA repair, recombination, and replication processes. A single active site processes both recessed ends and 5'-flap substrates. By initiating enzyme reactions in crystals, we have trapped hExo1 reaction intermediates that reveal structures of these substrates before and after their exo- and endonucleolytic cleavage, as well as structures of uncleaved, unthreaded, and partially threaded 5' flaps. Their distinctive 5' ends are accommodated by a small, mobile arch in the active site that binds recessed ends at its base and threads 5' flaps through a narrow aperture within its interior. A sequence of successive, interlocking conformational changes guides the two substrate types into a shared reaction mechanism that catalyzes their cleavage by an elaborated variant of the two-metal, in-line hydrolysis mechanism. Coupling of substrate-dependent arch motions to transition-state stabilization suppresses inappropriate or premature cleavage, enhancing processing fidelity. The striking reduction in flap conformational entropy is catalyzed, in part, by arch motions and transient binding interactions between the flap and unprocessed DNA strand. At the end of the observed reaction sequence, hExo1 resets without relinquishing DNA binding, suggesting a structural basis for its processivity.

Duke Scholars

Altmetric Attention Stats
Dimensions Citation Stats

Published In

Proc Natl Acad Sci U S A

DOI

EISSN

1091-6490

Publication Date

June 6, 2017

Volume

114

Issue

23

Start / End Page

6010 / 6015

Location

United States

Related Subject Headings

  • Substrate Specificity
  • Protein Conformation
  • Hydrolysis
  • Humans
  • Exodeoxyribonucleases
  • Endonucleases
  • DNA-Binding Proteins
  • DNA Repair Enzymes
  • DNA Repair
  • DNA
 

Citation

APA
Chicago
ICMJE
MLA
NLM
Shi, Y., Hellinga, H. W., & Beese, L. S. (2017). Interplay of catalysis, fidelity, threading, and processivity in the exo- and endonucleolytic reactions of human exonuclease I. Proc Natl Acad Sci U S A, 114(23), 6010–6015. https://doi.org/10.1073/pnas.1704845114
Shi, Yuqian, Homme W. Hellinga, and Lorena S. Beese. “Interplay of catalysis, fidelity, threading, and processivity in the exo- and endonucleolytic reactions of human exonuclease I.Proc Natl Acad Sci U S A 114, no. 23 (June 6, 2017): 6010–15. https://doi.org/10.1073/pnas.1704845114.
Shi Y, Hellinga HW, Beese LS. Interplay of catalysis, fidelity, threading, and processivity in the exo- and endonucleolytic reactions of human exonuclease I. Proc Natl Acad Sci U S A. 2017 Jun 6;114(23):6010–5.
Shi, Yuqian, et al. “Interplay of catalysis, fidelity, threading, and processivity in the exo- and endonucleolytic reactions of human exonuclease I.Proc Natl Acad Sci U S A, vol. 114, no. 23, June 2017, pp. 6010–15. Pubmed, doi:10.1073/pnas.1704845114.
Shi Y, Hellinga HW, Beese LS. Interplay of catalysis, fidelity, threading, and processivity in the exo- and endonucleolytic reactions of human exonuclease I. Proc Natl Acad Sci U S A. 2017 Jun 6;114(23):6010–6015.
Journal cover image

Published In

Proc Natl Acad Sci U S A

DOI

EISSN

1091-6490

Publication Date

June 6, 2017

Volume

114

Issue

23

Start / End Page

6010 / 6015

Location

United States

Related Subject Headings

  • Substrate Specificity
  • Protein Conformation
  • Hydrolysis
  • Humans
  • Exodeoxyribonucleases
  • Endonucleases
  • DNA-Binding Proteins
  • DNA Repair Enzymes
  • DNA Repair
  • DNA