The N-terminal extensions of Deinococcus radiodurans Dps-1 mediate DNA major groove interactions as well as assembly of the dodecamer

Gargi Bhattacharyya, Anne Grove

Research output: Contribution to journalArticlepeer-review

32 Scopus citations


Dps (DNA protection during starvation) proteins play an important role in the protection of prokaryotic macromolecules from damage by reactive oxygen species. Previous studies have suggested that the lysine-rich N-terminal tail of Dps proteins participates in DNA binding. In comparison with other Dps proteins, Dps-1 from Deinococcus radiodurans has an extended N terminus comprising 55 amino acids preceding the first helix of the 4-helix bundle monomer. In the crystal structure of Dps-1, the first ∼30 N-terminal residues are invisible, and the remaining 25 residues form a loop that harbors a novel metal-binding site. We show here that deletion of the flexible N-terminal tail obliterates DNA/Dps-1 interaction. Surprisingly, deletion of the entire N terminus also abolishes dodecameric assembly of the protein. Retention of the N-terminal metal site is necessary for formation of the dodecamer, and metal binding at this site facilitates oligomerization of the protein. Electrophoretic mobility shift assays using DNA modified with specific major/minor groove reagents further show that Dps-1 interacts through the DNA major groove. DNA cyclization assays suggest that dodecameric Dps-1 does not wrap DNA about itself. A significant decrease in DNA binding affinity accompanies a reduction in duplex length from 22 to 18 bp, but only for dodecameric Dps-1. Our data further suggest that high affinity DNA binding depends on occupancy of the N-terminal metal site. Taken together, the mode of DNA interaction by dodecameric Dps-1 suggests interaction of two metal-anchored N-terminal tails in successive DNA major grooves, leading to DNA compaction by formation of stacked protein-DNA layers.

Original languageEnglish (US)
Pages (from-to)11921-11930
Number of pages10
JournalJournal of Biological Chemistry
Issue number16
StatePublished - Apr 20 2007

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology


Dive into the research topics of 'The N-terminal extensions of Deinococcus radiodurans Dps-1 mediate DNA major groove interactions as well as assembly of the dodecamer'. Together they form a unique fingerprint.

Cite this