Effects of prokaryotic termination signals on RNA polymerase II transcription in HeLa cells

Three prokaryotic termination signals, the Escherichia coli trp attenuator, lambda 4S RNA terminator, and lambda tR1 terminator, were examined as to their effects on transcription in vivo in HeLa cells. The trp attenuator inhibited the expression of downstream genes in an orientation-dependent manner, but both the lambda 4S RNA and lambda tR1 terminators did not. Furthermore, a point mutation of the attenuator that disrupted the secondary structure of mRNA abolished this inhibitory effect. These results suggest that an attenuator-like secondary structure is effective in inhibiting transcriptional elongation by RNA polymerase II.