Regulation of transcription of coronaviruses.

ABSTRACT

To study factors involved in regulation of transcription of coronaviruses, we constructed defective interfering (DI) RNAs containing sg RNA promoters at multiple positions. Analysis of the amounts of sg DI RNA produced by these DIs resulted in the following observations (i) a downstream promoter downregulates an upstream promoter; (ii) an upstream promoter has little or no effect on the activity of a downstream promoter. Our data suggest that attenuation of upstream promoter activities by downstream promoter sequences plays an important role in regulating the amounts of sg RNAs produced by coronaviruses. Our observations are in accordance with the models proposed by Konings et al. and Sawicki and Sawicki.