User:Meng Han Liu/Sandbox 1: Difference between revisions
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#A specific terminator protein that can bind ''Ter'' | #A specific terminator protein that can bind ''Ter'' | ||
[[Image:Circular chromosomes of E. coli & B. subtilis.jpg|thumb|500x275px|alt=Circular chromosomes of E. coli and B. subtilis|The circular chromosomes of E. coli (left) and B. subtilis (right) showing their respective origin of replication (''Ori C''), direction of the two replication forks (red arrows) and their subsequent fork traps (blue and green).]] | |||
===DNA terminator (''Ter'') sites=== | ===DNA terminator (''Ter'') sites=== | ||
''Ter'' is a short consensus DNA sequence (around 20 base pairs long) that enables binding of its cognate terminator protein in order to arrest or halt replication fork progression in a polar manner i.e. it blocks replication fork coming in one direction (the non-permissive side) but allows passage when replication fork approaches from the other direction (the permissive side) <ref>Kamada, K., et al., Structure of a replication-terminator protein complexed with DNA. Nature (London), 1996. 383(6601): p. 598-603</ref>. In both ''E. coli'' and ''B. subtilis'', multiple ''Ter'' sites are organized into two subgroups that flank the terminus region. Since replication fork arrest is unidirectional, ''Ter'' sites are distributed so that one subgroup only arrests the clockwise-moving fork while the other subgroup only arrests the anti-clockwise moving fork <ref>Duggin, I.G. and J.A. Wilce, Termination of replication in bacteria. eLS2005: John Wiley & Sons, Ltd</ref>. A suggestive reason for the presence of multiple ''Ter'' sites is to act as a safety measure to ensure termination of replication and fork fusion occur within the terminus region even if one of the replication forks managed to precede the innermost ''Ter'' sites. | ''Ter'' is a short consensus DNA sequence (around 20 base pairs long) that enables binding of its cognate terminator protein in order to arrest or halt replication fork progression in a polar manner i.e. it blocks replication fork coming in one direction (the non-permissive side) but allows passage when replication fork approaches from the other direction (the permissive side) <ref>Kamada, K., et al., Structure of a replication-terminator protein complexed with DNA. Nature (London), 1996. 383(6601): p. 598-603</ref>. In both ''E. coli'' and ''B. subtilis'', multiple ''Ter'' sites are organized into two subgroups that flank the terminus region. Since replication fork arrest is unidirectional, ''Ter'' sites are distributed so that one subgroup only arrests the clockwise-moving fork while the other subgroup only arrests the anti-clockwise moving fork <ref>Duggin, I.G. and J.A. Wilce, Termination of replication in bacteria. eLS2005: John Wiley & Sons, Ltd</ref>. A suggestive reason for the presence of multiple ''Ter'' sites is to act as a safety measure to ensure termination of replication and fork fusion occur within the terminus region even if one of the replication forks managed to precede the innermost ''Ter'' sites. | ||
===DNA terminator proteins=== | ===DNA terminator proteins=== | ||
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==In ''E. coli'': Tus-''Ter'' complex== | |||
==RTP== | ==In ''B. subtilis'': RTP-''Ter'' complex== | ||
<Structure load='1f4k' size='400' frame='true' align='right' caption='Insert caption here' scene='Insert optional scene name here' /> | <Structure load='1f4k' size='400' frame='true' align='right' caption='Insert caption here' scene='Insert optional scene name here' /> | ||
