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Media type:
E-Article
Title:
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
Contributor:
Nakamura, Kenta;
Katayama, Tsutomu
Published:
Wiley, 2010
Published in:
Molecular Microbiology, 76 (2010) 2, Seite 302-317
Language:
English
DOI:
10.1111/j.1365-2958.2010.07074.x
ISSN:
0950-382X;
1365-2958
Origination:
Footnote:
Description:
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.