title: Identification of functional domains of the Escherichia coli SeqA protein.
abstract: The Escherichia coli SeqA protein, a negative regulator of chromosomal DNA replication, prevents the overinitiation of replication within one cell cycle by binding to hemimethylated G-mA-T-C sequences in the replication origin, oriC. In addition to the hemimethylated DNA-binding activity, the SeqA protein has a self-association activity, which is also considered to be essential for its regulatory function in replication initiation. To study the functional domains responsible for the DNA-binding and self-association activities, we performed a deletion analysis of the SeqA protein and found that the N-terminal (amino acid residues 1-59) and the C-terminal (amino acid residues 71-181) regions form structurally distinct domains. The N-terminal domain, which is not involved in DNA binding, has the self-association activity. In contrast, the C-terminal domain, which lacks the self-association activity, specifically binds to the hemimethylated G-mA-T-C sequence. Therefore, two essential SeqA activities, self-association and DNA-binding, are independently performed by the structurally distinct N-terminal and C-terminal domains, respectively.
authors.affiliation: RIKEN Genomic Sciences Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan.
authors.forename: Norie
authors.initials: N
authors.lastname: Fujikawa
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Kurumizaka
authors.forename: Mitsuyoshi
authors.initials: M
authors.lastname: Yamazoe
authors.forename: Sota
authors.initials: S
authors.lastname: Hiraga
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Yokoyama
mesh_terms: D001425:Bacterial Outer Membrane Proteins; D002850:Chromatography, Gel; D004247:DNA / Q000378:metabolism; D019175:DNA Methylation; D004261:DNA Replication / Q000502:physiology; D004268:DNA-Binding Proteins; D004926:Escherichia coli; D029968:Escherichia coli Proteins; D016297:Mutagenesis, Site-Directed; D017434:Protein Structure, Tertiary / Q000502:physiology; D017384:Sequence Deletion; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics*
chemical_list: D001425:Bacterial Outer Membrane Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C089746:SeqA protein, E coli; D014157:Transcription Factors; D004247:DNA