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Sequence-Specific Interactions in the Tus-Ter Complex and the Effect of Base Pair Substitutions on Arrest of DNA Replication in Escherichia coli     
Yazarlar (2)
Prof. Dr. Fatma Filiz ARI Prof. Dr. Fatma Filiz ARI
Kırşehir Ahi Evran Üniversitesi, Türkiye
Thomas Hill
Devamını Göster
Özet
Arrest of DNA replication in Escherichia coli is mediated by specific interactions between the Tus protein and terminator (Ter) sequences. Binding of Tus to a Ter site forms a asymmetric protein-DNA complex that arrests DNA replication in an orientation-dependent fashion. In this study, mutant Ter sites carrying single base pair substitutions at 16 different positions were examined for their ability to bind purified Tus protein and arrest DNA replication. In vitro competition assays demonstrated that base pair substitutions at positions 8-19 had significant effects on the free energy of Tus binding (ΔΔΔG0 of 1.5 to >4.0 kcal/mol). Concomitant with loss of binding affinity, mutations at these positions also showed significantly lower or undetectable replication arrest activities in vivo. Substitutions at positions 6, 20, and 21 had moderate effects on Tus-Ter interactions, suggesting that these base pairs contribute to, but are not absolutely critical for, Tus binding. Even though the effects on binding were minimal, these Ter mutants were not as efficient as wild type Tus-TerB complexes at arresting replication forks. Three new potential Ter sites, referred to as TerH, TerI, and TerJ, were identified by searching the E. coli genome for sequence similarity to a consensus Ter site sequence.
Anahtar Kelimeler
Makale Türü Özgün Makale
Makale Alt Türü SSCI, AHCI, SCI, SCI-Exp dergilerinde yayımlanan tam makale
Dergi Adı JOURNAL OF BIOLOGICAL CHEMISTRY
Dergi ISSN 0021-9258
Dergi Tarandığı Indeksler SCI
Makale Dili İngilizce
Basım Tarihi 10-1997
Cilt No 272
Sayı 42
Sayfalar 26448 / 26456
Doi Numarası 10.1074/jbc.272.42.26448