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Tus, also known as terminus utilization substance, is a protein that binds to terminator sequences and acts as a counter-helicase when it comes in contact with an advancing helicase.〔 The bound Tus protein effectively halts DNA polymerase movement.〔 Tus helps end DNA replication in prokaryotes.〔Slonczewski, Joan, and John Watkins. Foster. Microbiology: An Evolving Science. New York: W.W. Norton &, 2009. Print.〕 In ''E Coli'', Tus binds to 10 closely related sites encoded in the chromosome. These sites bind 23 base-pairs. The 10 sites are called ''Ter'' sites, and are designated ''TerA'', ''TerB'', ..., ''TerJ''. These binding sites are asymmetric, such that when a Tus-Ter complex (Tus protein bound to a Ter site) is encountered by a replication fork from one direction, the complex is dissociated and replication continues (permissive). But when encountered from the other direction, the Tus-Ter complex provides a much larger kinetic barrier and halts replication (non-permissive). The multiple ''Ter'' sites in the chromosome are oriented such that the two oppositely moving replication forks are both stalled in the desired termination region. ''Bacillus subtilis'' utilize replication terminator protein (RTP) instead of Tus. ==Further reading== * "Interaction of the Escherichia coli replication terminator protein (Tus) with DNA: a model derived from DNA-binding studies of mutant proteins by surface plasmon resonance." * "Replication termination in Escherichia coli: structure and antihelicase activity of the Tus-Ter complex." * "A molecular mousetrap determines polarity of termination of DNA replication in E. coli." * "Isolation and characterization of mutants of Tus, the replication arrest protein of Escherichia coli." * "Biophysical characteristics of Tus, the replication arrest protein of Escherichia coli." * "Structure of a replication-terminator protein complexed with DNA." * * (Structure at protein data bank ) 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Tus (biology)」の詳細全文を読む スポンサード リンク
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