MOT1-catalyzed TBP-DNA disruption: uncoupling DNA conformational change and role of upstream DNA

SNF2/SWI2-related ATPases employ ATP hydrolysis to disrupt protein-DNA inte ractions, but how ATP hydrolysis is coupled to disruption is not understood . Here we examine the mechanism of action of MOT1, a yeast SNF2/SWI2-relate d ATPase that uses ATP hydrolysis to remove TATA binding protein (TBP) from DNA, MOT1 function requires a 17 bp DNA 'handle' upstream of the TATA box, which must be double stranded. Remarkably, MOT1-catalyzed disruption of TB P-DNA does not appear to require DNA strand separation, DNA bending or twis ting of the DNA helix. Thus, TBP-DNA disruption is accomplished in a reacti on apparently not driven by a change in DNA structure. MOT1 action is suppo rted by DNA templates in which the handle is connected to the TATA box via single-stranded DNA, indicating that the upstream duplex DNA can be conform ationally uncoupled from the TATA box. Combining these results with propose d similarities between SNF2/SWI2 ATPases and helicases, we suggest that MOT 1 uses ATP hydrolysis to translocate along the handle and thereby disrupt i nteractions between TBP and DNA.