Effects of Escherichia coli Nus A protein on transcription termination in vitro are not increased or decreased by DNA sequences sufficient for antitermination in vivo

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Abstract
The ability of Escherichia coli Nus A protein to recognize specific DNA or RNA sequences in vitro was tested by using transcription templates a variety of promoters, transcription terminators, and antitermination-conferring regions. We conclude that the effects of Nus A on termination are not qualitatively or quantitatively altered by sequences present in promoters, Rho-dependent terminators, or antitermination-conferring regions. Nus A was also shown to increase termination at the rrnC Rho-independent T1 terminator by a mechanism that is independent of the promoter or sequences involved in antitermination. Altogether, these observations argue against a direct Nus A-nuclei acid interaction affecting termination in vitro. Together with the results described in the accompanying paper [Sigmund, C.D., and Morgan, E.A. (1988) Biochemistry (preceding paper in this issue)], these results suggest that the effects of Nus A on termination in vitro may not be related to the in vivo functions of Nus A.