Interacting selectively and non-covalently with a sequence of DNA that is an enhancer region that helps activate transcription of a gene or operon by a bacterial-type RNA polymerase. Enhancers for sigma-54 holoenzymes are typically located 80 to 150 base pairs upstream from the transcription start site, although they can be further away or may be downstream of the promoter. Some transcription units dependent on sigma-70 holoenzymes may also include enhancer sequences.