RTP and Tus: Difference between revisions
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His144 is a particularly important residue - it exists as its conjugate acid in the locked complex, forming hydrogen bonds with C6. Other residues - for example Phe140 and Gly149 - are also strictly conserved amongst different species' Tus protiens; many of the conserved residues among different ''Ter'' sites make base-specific contacts with Tus. | His144 is a particularly important residue - it exists as its conjugate acid in the locked complex, forming hydrogen bonds with C6. Other residues - for example Phe140 and Gly149 - are also strictly conserved amongst different species' Tus protiens; many of the conserved residues among different ''Ter'' sites make base-specific contacts with Tus. | ||
The locked Tus-''Ter'' complex is the most stable known monomeric DNA binding protein with a double-stranded sequence-specific recognition sequence - a half life of 550min has been reported (Mulcair, 2006). The formation of a large hydrogen-bond network is critical to sequence recognition and the stability of the twisted β-strands lying across the major groove. | The locked Tus-''Ter'' complex is the most stable known monomeric DNA binding protein with a double-stranded sequence-specific recognition sequence - a half life of 550min has been reported (Mulcair, 2006). The formation of a large hydrogen-bond network is critical to sequence recognition and the stability of the twisted β-strands lying across the major groove. | ||
'''When we thought we had a nice, elegant theory, someone had to come screw it all up.''' | '''When we thought we had a nice, elegant theory, someone had to come screw it all up.''' | ||
In 2008, Bastia ''et al'' proposed that Tus is actually a polar antitranslocase, and that an AT-GC transversion at position 6 did not affect DnaB-translocation ''in vitro''. Bastia et al suggested that the base-flipping of C6 functions as a fail-safe mechanism, and that the replication fork is halted primarily by Tus-DnaB and Tus-''Ter'' interactions. | |||
<Structure load='1ECR' size='400' frame='true' align='left' caption='Tus complexed with Ter DNA (Kamada ''et al'' 1996)' scene='Insert optional scene name here' /> | <Structure load='1ECR' size='400' frame='true' align='left' caption='Tus complexed with Ter DNA (Kamada ''et al'' 1996)' scene='Insert optional scene name here' /> | ||