<p>RtcR is a sigma54-dependent enhancer binding protein [<cite idref="PUB00012944"/>] that activates transcription of the rtcBA operon. The product of the rtcA gene is an RNA 3 -terminal phosphate cyclase [<cite idref="PUB00012945"/>]. This domain is found at the N terminus of the RtcR sequence. RtcR, and other sigma54-dependent activators, contain <db_xref db="INTERPRO" dbkey="IPR002078"/> in the central region of the protein sequence.</p>