passages.id: split_4_test_353_passage
passages.type: progene_text
passages.text: The in vitro properties of the most extreme trans dominant - negative mutants altered in the GEME motif ( and the mutant characteristics in vivo ) were similar to those of certain previously identified active - site mutants , suggesting that the altered RNA polymerases were capable of promoter binding and RNA chain initiation but were deficient in the subsequent transcriptional stage .