Structure and conformational transitions of the of E. Coureplicative helicase DnaB protein hexamer - SsDNA complex

M. J. Jezewska, Wlodzimierz Bujalowski

Research output: Contribution to journalArticle

Abstract

We present evidence that, in the presence of the ATP nonhydrolyzable analog AMP-PNP, the DnaB helicase binds polymer ssDNA with the site-size of 20± 3 nucleotides per protein hexamer. Studies of the 20-mer binding to the DnaB hexamer show that the hexamer has only a single, strong binding site for ssDNA. Photo-cross-linking experiments indicate that only a single subunit is primarily in contact with ssDNA. This surprisingly very low site-size of the large hexameric helicase-ssDNA complex, the existence of only a single, strong ssDNA binding site on the hexamer, and the results of photo-cross-linking experiments preclude the possibility of extensive wrapping of the ssDNA around the hexamer and formation of the complex in which all six protomers are simultaneously bound to ss nucleic acid. These results indicate that long-range allosteric interactions occur on the level of the quaternary structure of the hexameric enzyme, leading to the selection of a limited set of subunits as a binding site for ssDNA. We provide the first direct evidence of dramatic global conformational changes of the DnaB hexamer, induced by nucleotide cofactors and ssDNA binding, and the presence of multiple conformational states of the enzyme.

Original languageEnglish (US)
JournalFASEB Journal
Volume10
Issue number6
StatePublished - 1996

Fingerprint

DnaB Helicases
single-stranded DNA
Binding Sites
Nucleotides
Adenylyl Imidodiphosphate
Proteins
proteins
Protein Subunits
Enzymes
binding sites
Nucleic Acids
Polymers
Adenosine Triphosphate
Experiments
crosslinking
nucleotides
protein subunits
enzymes
nucleic acids
polymers

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Biochemistry
  • Cell Biology

Cite this

@article{827dde09861445f3aaf3cb42308f0958,
title = "Structure and conformational transitions of the of E. Coureplicative helicase DnaB protein hexamer - SsDNA complex",
abstract = "We present evidence that, in the presence of the ATP nonhydrolyzable analog AMP-PNP, the DnaB helicase binds polymer ssDNA with the site-size of 20± 3 nucleotides per protein hexamer. Studies of the 20-mer binding to the DnaB hexamer show that the hexamer has only a single, strong binding site for ssDNA. Photo-cross-linking experiments indicate that only a single subunit is primarily in contact with ssDNA. This surprisingly very low site-size of the large hexameric helicase-ssDNA complex, the existence of only a single, strong ssDNA binding site on the hexamer, and the results of photo-cross-linking experiments preclude the possibility of extensive wrapping of the ssDNA around the hexamer and formation of the complex in which all six protomers are simultaneously bound to ss nucleic acid. These results indicate that long-range allosteric interactions occur on the level of the quaternary structure of the hexameric enzyme, leading to the selection of a limited set of subunits as a binding site for ssDNA. We provide the first direct evidence of dramatic global conformational changes of the DnaB hexamer, induced by nucleotide cofactors and ssDNA binding, and the presence of multiple conformational states of the enzyme.",
author = "Jezewska, {M. J.} and Wlodzimierz Bujalowski",
year = "1996",
language = "English (US)",
volume = "10",
journal = "FASEB Journal",
issn = "0892-6638",
publisher = "FASEB",
number = "6",

}

TY - JOUR

T1 - Structure and conformational transitions of the of E. Coureplicative helicase DnaB protein hexamer - SsDNA complex

AU - Jezewska, M. J.

AU - Bujalowski, Wlodzimierz

PY - 1996

Y1 - 1996

N2 - We present evidence that, in the presence of the ATP nonhydrolyzable analog AMP-PNP, the DnaB helicase binds polymer ssDNA with the site-size of 20± 3 nucleotides per protein hexamer. Studies of the 20-mer binding to the DnaB hexamer show that the hexamer has only a single, strong binding site for ssDNA. Photo-cross-linking experiments indicate that only a single subunit is primarily in contact with ssDNA. This surprisingly very low site-size of the large hexameric helicase-ssDNA complex, the existence of only a single, strong ssDNA binding site on the hexamer, and the results of photo-cross-linking experiments preclude the possibility of extensive wrapping of the ssDNA around the hexamer and formation of the complex in which all six protomers are simultaneously bound to ss nucleic acid. These results indicate that long-range allosteric interactions occur on the level of the quaternary structure of the hexameric enzyme, leading to the selection of a limited set of subunits as a binding site for ssDNA. We provide the first direct evidence of dramatic global conformational changes of the DnaB hexamer, induced by nucleotide cofactors and ssDNA binding, and the presence of multiple conformational states of the enzyme.

AB - We present evidence that, in the presence of the ATP nonhydrolyzable analog AMP-PNP, the DnaB helicase binds polymer ssDNA with the site-size of 20± 3 nucleotides per protein hexamer. Studies of the 20-mer binding to the DnaB hexamer show that the hexamer has only a single, strong binding site for ssDNA. Photo-cross-linking experiments indicate that only a single subunit is primarily in contact with ssDNA. This surprisingly very low site-size of the large hexameric helicase-ssDNA complex, the existence of only a single, strong ssDNA binding site on the hexamer, and the results of photo-cross-linking experiments preclude the possibility of extensive wrapping of the ssDNA around the hexamer and formation of the complex in which all six protomers are simultaneously bound to ss nucleic acid. These results indicate that long-range allosteric interactions occur on the level of the quaternary structure of the hexameric enzyme, leading to the selection of a limited set of subunits as a binding site for ssDNA. We provide the first direct evidence of dramatic global conformational changes of the DnaB hexamer, induced by nucleotide cofactors and ssDNA binding, and the presence of multiple conformational states of the enzyme.

UR - http://www.scopus.com/inward/record.url?scp=33749097310&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33749097310&partnerID=8YFLogxK

M3 - Article

VL - 10

JO - FASEB Journal

JF - FASEB Journal

SN - 0892-6638

IS - 6

ER -