title: Dimeric configuration of SeqA protein bound to a pair of hemi-methylated GATC sequences.
abstract: The binding of SeqA protein to hemi-methylated GATC sequences (hemi-sites) regulates chromosome initiation and the segregation of replicated chromosome in Escherichia coli. We have used atomic force microscopy to examine the architecture of SeqA and the mode of binding of one molecule of SeqA to a pair of hemi-sites in aqueous solution. SeqA has a bipartite structure composed of a large and a small lobe. Upon binding of a SeqA molecule to a pair of hemi-sites, the larger lobe becomes visibly separated into two DNA binding domains, each of which binds to one hemi-site. The two DNA binding domains are held together by association between the two multimerization domains that make up the smaller lobe. The binding of each DNA binding domain to a hemi-site leads to bending of the bound DNA inwards toward the bound protein. In this way, SeqA adopts a dimeric configuration when bound to a pair of hemi-sites. Mutational analysis of the multimerization domain indicates that, in addition to multimerization of SeqA polypeptides, this domain contributes to the ability of SeqA to bind to a pair of hemi-sites and to its cooperative behavior.
authors.affiliation: Institute of Molecular Biology and Genetics, Seoul National University Seoul 151-742, Republic of Korea.
authors.forename: Sukhyun
authors.initials: S
authors.lastname: Kang
authors.forename: Joo Seok
authors.initials: JS
authors.lastname: Han
authors.forename: Keun Pill
authors.initials: KP
authors.lastname: Kim
authors.forename: Hye Yoon
authors.initials: HY
authors.lastname: Yang
authors.forename: Kyung Yong
authors.initials: KY
authors.lastname: Lee
authors.forename: Choo Bong
authors.initials: CB
authors.lastname: Hong
authors.forename: Deog Su
authors.initials: DS
authors.lastname: Hwang
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D001483:Base Sequence; D001665:Binding Sites; D004247:DNA / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D019175:DNA Methylation; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D019281:Dimerization; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D018625:Microscopy, Atomic Force; D009690:Nucleic Acid Conformation; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D013912:Threonine / Q000737:chemistry
chemical_list: D000596:Amino Acids; D001425:Bacterial Outer Membrane Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C089746:SeqA protein, E coli; D013912:Threonine; D004247:DNA