Dynamics of initiation, termination and reinitiation of DNA translocation by the motor protein EcoR124I.

ABSTRACT: Type I restriction enzymes use two motors to translocate DNA before carrying out DNA cleavage. The motor function is accomplished by amino-acid motifs typical for superfamily 2 helicases, although DNA unwinding is not observed. Using a combination of extensive single-molecule magnetic tweezers and stopped-flow bulk measurements, we fully characterized the (re)initiation of DNA translocation by EcoR124I. We found that the methyltransferase core unit of the enzyme loads the motor subunits onto adjacent DNA by allowing them to bind and initiate translocation. Termination of translocation occurs owing to dissociation of the motors from the core unit. Reinitiation of translocation requires binding of new motors from solution. The identification and quantification of further initiation steps--AT

SUBMITTER: Seidel R 

PROVIDER: S-EPMC1356320 | biostudies-literature | 2005 Dec

REPOSITORIES: biostudies-literature