Novel essential residues of Hda for interaction with DnaA in the regulatory inactivation of DnaA: Unique roles for Hda AAA+ Box VI and VII motifs

Kenta Nakamura, Tsutomu Katayama

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)

Abstract

Summary Escherichia coli ATP-DnaA initiates chromosomal replication. For preventing extra-initiations, a complex of ADP-Hda and the DNA-loaded replicase clamp promotes DnaA-ATP hydrolysis, yielding inactive ADP-DnaA. However, the Hda-DnaA interaction mode remains unclear except that the Hda Box VII Arg finger (Arg-153) and DnaA sensor II Arg-334 within each AAA+ domain are crucial for the DnaA-ATP hydrolysis. Here, we demonstrate that direct and functional interaction of ADP-Hda with DnaA requires the Hda residues Ser-152, Phe-118 and Asn-122 as well as Hda Arg-153 and DnaA Arg-334. Structural analyses suggest intermolecular interactions between Hda Ser-152 and DnaA Arg-334 and between Hda Phe-118 and the DnaA Walker B motif region, in addition to an intramolecular interaction between Hda Asn-122 and Arg-153. These interactions likely sustain a specific association of ADP-Hda and DnaA, promoting DnaA-ATP hydrolysis. Consistently, ATP-DnaA and ADP-DnaA interact with the ADP-Hda-DNA-clamp complex with similar affinities. Hda Phe-118 and Asn-122 are contained in the Box VI region, and their hydrophobic and electrostatic features are basically conserved in the corresponding residues of other AAA+ proteins, suggesting a conserved role for Box VI. These findings indicate novel interaction mechanisms for Hda-DnaA as well as a potentially fundamental mechanism in AAA+ protein interactions.

Original languageEnglish
Pages (from-to)302-317
Number of pages16
JournalMolecular Microbiology
Volume76
Issue number2
DOIs
Publication statusPublished - Apr 2010

All Science Journal Classification (ASJC) codes

  • Microbiology
  • Molecular Biology

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