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 ? ?

Matching UniProtKB/Swiss-Prot entries

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4 entries grouped by protein

1 entry

Protein alc (Protein unf)

Enterobacteria phage T4 (Bacteriophage T4) reference strain

1 entry

Protein kinase 0.7 (EC (Gene product 0.7) (Gp0.7) (Protein kinase gp0.7)

Escherichia phage T7 (Bacteriophage T7) reference strain

2 entries

Bacterial RNA polymerase inhibitor (Gene product 2) (Gp2)

Escherichia phage T7 (Bacteriophage T7) reference strain
Enterobacteria phage T3 (Bacteriophage T3)