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Crystal structure of a SeqA–N filament: implications for DNA replication and chromosome organization
Author(s) -
Guarné Alba,
Brendler Therese,
Zhao Qinghai,
Ghirlando Rodolfo,
Austin Stuart,
Yang Wei
Publication year - 2005
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7600634
Subject(s) - seqa protein domain , biology , dna , genetics , dna replication , chromosome segregation , microbiology and biotechnology , origin of replication , chromosome , gene
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.