Ss-LrpB from Sulfolobus solfataricus Condenses about 100 Base Pairs of Its Own Operator DNA into Globular Nucleoprotein Complexes

Eveline Peeters,Ronnie Willaert,Dominique Maes,Daniel Charlier

doi:10.1074/jbc.m600383200

Eveline Peeters, Ronnie Willaert + Show 2 more

Open Access

https://doi.org/10.1074/jbc.m600383200

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Abstract

Ss-LrpB from the hyperthermoacidophilic crenarchaeote Sulfolobus solfataricus P2 is a member of the Lrp-like family of Bacterial/Archaeal transcription regulators that binds its own control region at three regularly spaced and partially conserved 15-bp-long imperfect palindromes. We have used atomic force microscopy to analyze the architecture of Ss-LrpB.DNA complexes with a different stoichiometry formed with the wild type operator and with an operator mutant. Binding of dimeric Ss-LrpB to all three target sites is accompanied by the formation of globular complexes, in which the protein induces strong DNA deformations. Furthermore, DNA contour length foreshortening of these complexes indicates DNA wrapping, with about 100 bp being condensed. The average bending angle is 260 degrees . The establishment of protein-protein contacts between Ss-LrpB dimers in these globular complexes will contribute to the cooperativity of the binding. The profound remodeling of the control region is expected to have a strong impact on gene expression and might constitute the key element in the autoregulatory process.

Highlights

Archaeal transcription is a chimera of eukaryotic and bacterial features
Ss-LrpB Behaves Mainly as a Dimer in Solution—Dimethyl suberimidate (DMSI) cross-linking is a classical method used for the determination of the oligomeric state(s) of a protein [12]
We present a detailed analysis of the architecture of the nucleoprotein complexes formed by binding of Ss-LrpB to the operator region of its own gene

Summary

Introduction

Archaeal transcription is a chimera of eukaryotic and bacterial features (for a recent review, see Ref. 1). Binding of dimeric Ss-LrpB to all three target sites is accompanied by the formation of globular complexes, in which the protein induces strong DNA deformations. Measurements of contour length and bending angle of the complexes indicate that Ss-LrpB binding to the three targets accompanies pronounced DNA bending and condensation.

Results

Conclusion