Escherichia coli RNA polymerase translocation is accompanied by periodic bending of the DNA

RNA polymerase was halted in consecutive registers of RNA synthesis ranging from registers 11 to 68. Non-denaturing gel electrophoresis shows that the mobility of the complexes varies (up to 15%), indicating that halted compl exes differ in their conformation. The electrophoretic mobility changes wit h an approximate 10-register periodicity. The change of the mobility can be attributed to relative changes of RNA polymerase-induced bending angle. We suggest that the periodicity of the bending angle reflects periodic change s of the conformation of the halted complexes that might have relevance for the translocation mechanism.