שאלה | Under highly stressful circumstances E. coli is able to down regulate almost all of the normally active genes and initiate transcription of stress response genes. This event is due to which one of the following?

Under highly stressful circumstances E. coli is able to down regulate almost all of the normally active genes and initiate transcription of stress response genes. This event is due to which one of the following?

		Stress activated phosphorylation of the normal RNA polymerase (σ) subunit.
		Transcription of small basic proteins (SBPs) which bind most of the E. coli genomic DNA into an inaccessible higher-order structure resembling eukaryotic chromatin.
		An increase in cAMP, which is a prokaryotic starvation signal. As a result, the CAP protein initiates transcription of a small subset of response genes.
		Degradation of the normal β subunits of RNA polymerase and their replacement with a second copy of β'.
		The transcription of the heat-shock genes.
		None of the above.