Bacterial host transcription shutoff by virus (kw:KW-1263)

Bacterial viruses are in competition with the host for the cellular transcription machinery, prompting many of them to inhibit host cell transcription while promoting regulated viral DNA transcription.
Many bacterial viruses, encode transcription factors that specifically inhibit the activity of the host RNA polymerase (RNAP) thereby sabotaging and sometimes appropriating the host transcription machinery to serve their needs.
Bacteriophage T7, for example, encodes an inhibitor of host RNAP, the gp2 protein. Gp2 ensures that host RNAP does not interfere with transcription by the viral polymerase at late stages of infection. In this case, the inhibition of host RNAP facilitates the switching between host and phage RNA polymerase.

Here are some examples of viruses inducing transcriptional shutoff:

Family	Genus	Virus	Viral protein	shutoff mechanism	Viral transcription strategy	ref.
Myoviridae	T4likevirus	Enterobacteria phage T4	Alc protein	Site-specific transcription termination factor	Viral DNA protected with 5-hydroxymethyl cytosine
			Asia protein	anti-σ factor protein	T4 MotA compensates for the absence of CTD/UP element interaction during initiation
Podoviridae	T7likevirus	Enterobacteria phage T7	gp2 protein	σ factor displacement	Viral polymerase
Siphoviridae	Unclassified	Xanthomonas oryzae bacteriophage Xp10	p7 protein	σ factor displacement	Viral polymerase
Podoviridae	Phikmvlikevirus	fKMV-related phages	gp2like protein	σ factor displacement (probable)	Viral polymerase
Podoviridae	Phieco32likevirus	Enterobacteria phage PhiEco32	gp79 protein	Inhibits σ factor transcription	Putative viral σ factor gp36
Siphoviridae	Unclassified	Thermus thermophilus phage P23-45	gp39 protein	σ factor displacement	Transcription from extended ?-10 promoters not affected
Myoviridae	Twortlikevirus	Staphylococcus phage G1	gp67 protein	Binds to σ factor and inhibits the function of the α subunit CTD. Inhibits ribosomal RNA transcription.	?
Myoviridae	Spounalikevirus	Bacillus phage SPO1	gp40	?	?