1XRX

Crystal structure of a DNA-binding protein

Summary for 1XRX

• Entry DOI: 10.2210/pdb1xrx/pdb
• Related: 1LRR
• Descriptor: SeqA protein, CALCIUM ION (3 entities in total)
• Functional Keywords: protein filament, left-handed helix, dna replication inhibitor, replication inhibitor
• Biological source: Escherichia coli
• Total number of polymer chains: 4
• Total formula weight: 22820.81

Authors

Guarne, A.,Brendler, T.,Zhao, Q.,Ghirlando, R.,Austin, S.,Yang, W. (deposition date: 2004-10-16, release date: 2005-05-10, Last modification date: 2024-11-20)

Primary citation

Guarne, A.,Brendler, T.,Zhao, Q.,Ghirlando, R.,Austin, S.,Yang, W.
Crystal structure of a SeqA-N filament: implications for DNA replication and chromosome organization.
Embo J., 24:1502-1511, 2005

PubMed Abstract: Escherichia coli SeqA binds clusters of transiently hemimethylated GATC sequences and sequesters the origin of replication, oriC, from methylation and premature reinitiation. Besides oriC, SeqA binds and organizes newly synthesized DNA at replication forks. Binding to multiple GATC sites is crucial for the formation of stable SeqA-DNA complexes. Here we report the crystal structure of the oligomerization domain of SeqA (SeqA-N). The structural unit of SeqA-N is a dimer, which oligomerizes to form a filament. Mutations that disrupt filament formation lead to asynchronous DNA replication, but the resulting SeqA dimer can still bind two GATC sites separated from 5 to 34 base pairs. Truncation of the linker between the oligomerization and DNA-binding domains restricts SeqA to bind two GATC sites separated by one or two full turns. We propose a model of a SeqA filament interacting with multiple GATC sites that accounts for both origin sequestration and chromosome organization.

PubMed: 15933720
DOI: 10.1038/sj.emboj.7600634

Experimental method

X-RAY DIFFRACTION (2.15 Å)