2W58

Crystal Structure of the DnaI

Summary for 2W58

• Entry DOI: 10.2210/pdb2w58/pdb
• Descriptor: PRIMOSOME COMPONENT (HELICASE LOADER), ADENOSINE-5'-DIPHOSPHATE, MAGNESIUM ION, ... (5 entities in total)
• Functional Keywords: dnai, helicase, atp-binding, nucleotide-binding, hydrolase
• Biological source: GEOBACILLUS KAUSTOPHILUS HTA426
• Total number of polymer chains: 2
• Total formula weight: 47668.79

Authors

Tsai, K.L.,Lo, Y.H.,Sun, Y.J.,Hsiao, C.D. (deposition date: 2008-12-08, release date: 2009-12-22, Last modification date: 2024-05-08)

Primary citation

Tsai, K.L.,Lo, Y.H.,Sun, Y.J.,Hsiao, C.D.
Molecular Interplay between the Replicative Helicase Dnac and its Loader Protein Dnai from Geobacillus Kaustophilus.
J.Mol.Biol., 393:1056-, 2009

PubMed 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 GkDnaC(6)-GkDnaI(6) 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 A 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.

PubMed: 19744498
DOI: 10.1016/J.JMB.2009.09.002

Experimental method

X-RAY DIFFRACTION (2.5 Å)