Format

Send to

Choose Destination
J Biol Chem. 2015 Aug 28;290(35):21200-12. doi: 10.1074/jbc.M114.630400. Epub 2015 Jun 17.

A Three-protein Charge Zipper Stabilizes a Complex Modulating Bacterial Gene Silencing.

Author information

1
From the Biomolecular NMR Laboratory, Department of Organic Chemistry, University of Barcelona, 08028 Barcelona, Spain, Centre de Biochimie Structurale, INSERM U1054, CNRS UMR 5048, Université Montpellier 1 and 2, 34092 Montpellier, France.
2
Institute for Research in Biomedicine (IRB-Barcelona), 08028 Barcelona, Spain, and.
3
Centre de Biochimie Structurale, INSERM U1054, CNRS UMR 5048, Université Montpellier 1 and 2, 34092 Montpellier, France.
4
the Structural Biology Unit, Center for Cooperative Research in Biosciences (CIC-bioGUNE), 48160 Elexalde, Derio, Spain omillet@cicbiogune.es.
5
From the Biomolecular NMR Laboratory, Department of Organic Chemistry, University of Barcelona, 08028 Barcelona, Spain, mpons@ub.edu.

Abstract

The Hha/YmoA nucleoid-associated proteins help selectively silence horizontally acquired genetic material, including pathogenicity and antibiotic resistance genes and their maintenance in the absence of selective pressure. Members of the Hha family contribute to gene silencing by binding to the N-terminal dimerization domain of H-NS and modifying its selectivity. Hha-like proteins and the H-NS N-terminal domain are unusually rich in charged residues, and their interaction is mostly electrostatic-driven but, nonetheless, highly selective. The NMR-based structural model of the complex between Hha/YmoA and the H-NS N-terminal dimerization domain reveals that the origin of the selectivity is the formation of a three-protein charge zipper with interdigitated complementary charged residues from Hha and the two units of the H-NS dimer. The free form of YmoA shows collective microsecond-millisecond dynamics that can by measured by NMR relaxation dispersion experiments and shows a linear dependence with the salt concentration. The number of residues sensing the collective dynamics and the population of the minor form increased in the presence of H-NS. Additionally, a single residue mutation in YmoA (D43N) abolished H-NS binding and the dynamics of the apo-form, suggesting the dynamics and binding are functionally related.

KEYWORDS:

charge zipper complexes; electrostatics; gene silencing; horizontal gene transfer; nuclear magnetic resonance (NMR); nucleoid-associated proteins; protein dynamic; protein-protein interaction

PMID:
26085102
PMCID:
PMC4571853
DOI:
10.1074/jbc.M114.630400
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for HighWire Icon for PubMed Central
Loading ...
Support Center