The DnaB·DnaC complex: A structure based on dimers assembled around an occluded channel

Montserrat Bárcena; Teresa Ruiz; Luis Enrique Donate; Susan E. Brown; Nicholas E. Dixon; Michael Radermacher; José María Carazo

doi:10.1093/emboj/20.6.1462

The DnaB·DnaC complex: A structure based on dimers assembled around an occluded channel

Montserrat Bárcena, Teresa Ruiz, Luis Enrique Donate, Susan E. Brown, Nicholas E. Dixon, Michael Radermacher, José María Carazo^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

66 Citations (Scopus)

Abstract

Replicative helicases are motor proteins;that unwind DNA at replication forks. Escherichia coli DnaB is the best characterized member of this family of enzymes. We present the 26 Å resolution three-dimensional structure of the DnaB hexamer in complex with its loading partner, DnaC, obtained from cryo-electron microscopy. Analysis of the volume brings insight into the elaborate way the two proteins interact, and provides a structural basis for control of the symmetry state and inactivation of the helicase by DnaC. The complex is arranged on the basis of interactions among DnaC and DnaB dimers. DnaC monomers are observed for the first time to arrange as three dumb-bell-shaped dimers that interlock into one of the faces of the helicase. This could be responsible for the freezing of DnaB in a C₃ architecture by its loading partner. The central channel of the helicase is almost occluded near the end opposite to DnaC, such that even single-stranded DNA could not pass through. We propose that the DnaB N-terminal domain is located at this face.

Original language	English
Pages (from-to)	1462-1468
Number of pages	7
Journal	EMBO Journal
Volume	20
Issue number	6
DOIs	https://doi.org/10.1093/emboj/20.6.1462
Publication status	Published - 15 Mar 2001

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title = "The DnaB·DnaC complex: A structure based on dimers assembled around an occluded channel",

abstract = "Replicative helicases are motor proteins;that unwind DNA at replication forks. Escherichia coli DnaB is the best characterized member of this family of enzymes. We present the 26 {\AA} resolution three-dimensional structure of the DnaB hexamer in complex with its loading partner, DnaC, obtained from cryo-electron microscopy. Analysis of the volume brings insight into the elaborate way the two proteins interact, and provides a structural basis for control of the symmetry state and inactivation of the helicase by DnaC. The complex is arranged on the basis of interactions among DnaC and DnaB dimers. DnaC monomers are observed for the first time to arrange as three dumb-bell-shaped dimers that interlock into one of the faces of the helicase. This could be responsible for the freezing of DnaB in a C3 architecture by its loading partner. The central channel of the helicase is almost occluded near the end opposite to DnaC, such that even single-stranded DNA could not pass through. We propose that the DnaB N-terminal domain is located at this face.",

keywords = "Cryo-electron microscopy, DNA replication, Helicases, Molecular motors, Three-dimensional reconstruction",

author = "Montserrat B{\'a}rcena and Teresa Ruiz and Donate, {Luis Enrique} and Brown, {Susan E.} and Dixon, {Nicholas E.} and Michael Radermacher and Carazo, {Jos{\'e} Mar{\'i}a}",

year = "2001",

month = mar,

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doi = "10.1093/emboj/20.6.1462",

language = "English",

volume = "20",

pages = "1462--1468",

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T1 - The DnaB·DnaC complex

T2 - A structure based on dimers assembled around an occluded channel

AU - Bárcena, Montserrat

AU - Ruiz, Teresa

AU - Donate, Luis Enrique

AU - Brown, Susan E.

AU - Dixon, Nicholas E.

AU - Radermacher, Michael

AU - Carazo, José María

PY - 2001/3/15

Y1 - 2001/3/15

N2 - Replicative helicases are motor proteins;that unwind DNA at replication forks. Escherichia coli DnaB is the best characterized member of this family of enzymes. We present the 26 Å resolution three-dimensional structure of the DnaB hexamer in complex with its loading partner, DnaC, obtained from cryo-electron microscopy. Analysis of the volume brings insight into the elaborate way the two proteins interact, and provides a structural basis for control of the symmetry state and inactivation of the helicase by DnaC. The complex is arranged on the basis of interactions among DnaC and DnaB dimers. DnaC monomers are observed for the first time to arrange as three dumb-bell-shaped dimers that interlock into one of the faces of the helicase. This could be responsible for the freezing of DnaB in a C3 architecture by its loading partner. The central channel of the helicase is almost occluded near the end opposite to DnaC, such that even single-stranded DNA could not pass through. We propose that the DnaB N-terminal domain is located at this face.

AB - Replicative helicases are motor proteins;that unwind DNA at replication forks. Escherichia coli DnaB is the best characterized member of this family of enzymes. We present the 26 Å resolution three-dimensional structure of the DnaB hexamer in complex with its loading partner, DnaC, obtained from cryo-electron microscopy. Analysis of the volume brings insight into the elaborate way the two proteins interact, and provides a structural basis for control of the symmetry state and inactivation of the helicase by DnaC. The complex is arranged on the basis of interactions among DnaC and DnaB dimers. DnaC monomers are observed for the first time to arrange as three dumb-bell-shaped dimers that interlock into one of the faces of the helicase. This could be responsible for the freezing of DnaB in a C3 architecture by its loading partner. The central channel of the helicase is almost occluded near the end opposite to DnaC, such that even single-stranded DNA could not pass through. We propose that the DnaB N-terminal domain is located at this face.

KW - Cryo-electron microscopy

KW - DNA replication

KW - Helicases

KW - Molecular motors

KW - Three-dimensional reconstruction

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DO - 10.1093/emboj/20.6.1462

M3 - Article

SN - 0261-4189

VL - 20

SP - 1462

EP - 1468

JO - EMBO Journal

JF - EMBO Journal

IS - 6

ER -

The DnaB·DnaC complex: A structure based on dimers assembled around an occluded channel

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