A MODEL FOR DNA-POLYMERASE TRANSLOCATION - WORM-LIKE MOVEMENT OF DNA WITHIN THE BINDING CLEFT

On the basis of recent results, we propose a model for DNA polymerase translocation along DNA. Human immunodeficiency virus reverse transcri ptase is taken as an example. According to the model, movement of the enzyme is the result of transition of the enzyme-bound DNA from the A- to B-form which is accompanied by lengthening of DNA within the bindi ng channel. The driving force of this transition is the increase in wa ter accessibility to the DNA-binding cleft after dNTP binding. dNTP hy drolysis proceeding during the following chemical step supplies the en ergy for the reverse B --> A transition of DNA. Translocation is consi dered to be an integral part of the stage of conformational change pre ceding catalysis and can be described as a worm-like movement of DNA w ithin the DNA-binding cleft.