Mechanisms of opening and closing of the bacterial replicative helicase

Abstract
Data availability
Article and author information
Metrics

Abstract

Assembly of bacterial ring-shaped hexameric replicative helicases on single-stranded (ss) DNA requires specialized loading factors. However, mechanisms implemented by these factors during opening and closing of the helicase, which enable and restrict access to an internal chamber, are not known. Here, we investigate these mechanisms in the Escherichia coli DnaB helicase•bacteriophage λ helicase loader (λP) complex. We show that five copies of λP bind at DnaB subunit interfaces and reconfigure the helicase into an open spiral conformation that is intermediate to previously observed closed ring and closed spiral forms; reconfiguration also produces openings large enough to admit ssDNA into the inner chamber. The helicase is also observed in a restrained inactive configuration that poises it to close on activating signal, and transition to the translocation state. Our findings provide insights into helicase opening, delivery to the origin and ssDNA entry, and closing in preparation for translocation.

Data availability

Cryogenic electron microscopy maps have been deposited with the EMDB under accession number EMD-7076Atomic coordinates have been deposited with the PDB under the accession code 6BBM

The following data sets were generated

1. Chase J
2. Catalano A
3. Noble AJ
4. Eng ET
5. Olinares PDB
6. Molloy KR
7. Pakotiprapha D
8. Samuels M
9. Chait BT
10. Georges Des A
11. Jeruzalmi D
(2018) Mechanisms of Opening and Closing of the Bacterial Replicative Helicase
Protein databank, 6BBM.

http://www.rcsb.org/structure/6BBM
1. Chase J
2. Catalano A
3. Noble AJ
4. Eng ET
5. Olinares PDB
6. Molloy KR
7. Pakotiprapha D
8. Samuels M
9. Chait BT
10. Georges Des A
11. Jeruzalmi D
(2018) Mechanisms of Opening and Closing of the Bacterial Replicative Helicase
Electron Microscopy Data Bank, EMD-7076.

http://www.ebi.ac.uk/pdbe/entry/emdb/EMD-7076

Article and author information

Author details

Jillian Chase

Department of Chemistry and Biochemistry, City College of New York, New York, United States

Competing interests
The authors declare that no competing interests exist.
Andrew Catalano

Department of Chemistry and Biochemistry, City College of New York, New York, United States

Competing interests
The authors declare that no competing interests exist.
Alex J Noble

National Resource for Automated Molecular Microscopy, Simons Electron Microscopy Center, New York Structural Biology Center, New York, United States

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0001-8634-2279
Edward T Eng

National Resource for Automated Molecular Microscopy, Simons Electron Microscopy Center, New York Structural Biology Center, New York, United States

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-8014-7269
Paul D B Olinares

Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, United States

Competing interests
The authors declare that no competing interests exist.
Kelley Molloy

Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, United States

Competing interests
The authors declare that no competing interests exist.
Danaya Pakotiprapha

Department of Biochemistry, Mahidol University, Bangkok, Thailand

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-5017-8283
Martin Samuels

Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States

Competing interests
The authors declare that no competing interests exist.
Brian Chait

Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, United States

Competing interests
The authors declare that no competing interests exist.
Amedee des Georges

Department of Chemistry and Biochemistry, City College of New York, New York, United States

For correspondence
amedee.desgeorges@asrc.cuny.edu

Competing interests
The authors declare that no competing interests exist.
David Jeruzalmi

Department of Chemistry and Biochemistry, City College of New York, New York, United States

For correspondence
dj@ccny.cuny.edu

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0001-5886-1370

Funding

National Institutes of Health (GM084162)

David Jeruzalmi

National Science Foundation (MCB 1818255)

David Jeruzalmi

National Institutes of Health (5G12MD007603-30)

David Jeruzalmi

Simons Foundation (SF349247)

Edward T Eng

Agouron Institute (F00316)

Edward T Eng

National Institutes of Health (OD019994)

Edward T Eng

Department of Education and Training (PA200A150068)

Jillian Chase

National Institutes of Health (P41 GM103314)

Brian Chait

National Institutes of Health (P41 GM109824)

Brian Chait

National Institutes of Health (F32GM128303)

Alex J Noble

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Copyright

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.