Title of article :
Molecular Interplay between the Replicative Helicase DnaC and Its Loader Protein DnaI from Geobacillus kaustophilus
Author/Authors :
Kuang-Lei Tsai، نويسنده , , Yu-Hua Lo، نويسنده , , Yuh-Ju Sun، نويسنده , , Chwan-Deng Hsiao، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2009
Pages :
14
From page :
1056
To page :
1069
Abstract :
Helicase loading factors are thought to transfer the hexameric ring-shaped helicases onto the replication fork during DNA replication. However, the mechanism of helicase transfer onto DNA remains unclear. In Bacillus subtilis, the protein DnaI, which belongs to the AAA+ family of ATPases, is responsible for delivering the hexameric helicase DnaC onto DNA. Here we investigated the interaction between DnaC and DnaI from Geobacillus kaustophilus HTA426 (GkDnaC and GkDnaI, respectively) and determined that GkDnaI forms a stable complex with GkDnaC with an apparent stoichiometry of GkDnaC6–GkDnaI6 in the absence of ATP. Surface plasmon resonance analysis indicated that GkDnaI facilitates loading of GkDnaC onto single-stranded DNA (ssDNA) and supports complex formation with ssDNA in the presence of ATP. Additionally, the GkDnaI C-terminal AAA+ domain alone could bind ssDNA, and binding was modulated by nucleotides. We also determined the crystal structure of the C-terminal AAA+ domain of GkDnaI in complex with ADP at 2.5 Å resolution. The structure not only delineates the binding of ADP in the expected Walker A and B motifs but also reveals a positively charged region that may be involved in ssDNA binding. These findings provide insight into the mechanism of replicative helicase loading onto ssDNA.
Keywords :
REPLICATION , helicase , loader , DnaI , DnaC
Journal title :
Journal of Molecular Biology
Serial Year :
2009
Journal title :
Journal of Molecular Biology
Record number :
1250670
Link To Document :
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