Facilitates transcription termination by a mechanism that involves Rho binding to the nascent RNA, activation of Rho's RNA-dependent ATPase activity, and release of the mRNA from the DNA template. Homohexamer. The homohexamer assembles into an open ring structure. Belongs to the Rho family. It is uncertain whether Met-1 or Met-43 is the initiator. Truncated N-terminus.