Arrange the following steps of the regulation of the trp operon in order of occurrence.

_The trp repressor protein binds to the operator
_levels of tryptophan rise and more is required
-Tryptophan binds to trp repressor protein and induces a conformational change
_Products of the trp gene synthesize tryptophan
_RNA polymerase binds to the promotor allowing transcription of the trp genes to proceed.
_The trp repressor protein blocks RNA polymerase from binding to the promotor.