Degradation of host chromosome by virus

The rapid synthesis of viral DNA necessitates access to a large pool of nucleoside 5'-triphophates. Some prokaryotic viruses degrade the host chromosome at the onset of infection. The breakdown products (nucleosides) can be reused to synthesize viral DNA (e.g. T2, T4, T6) or can be excreted from the host cell (e.g. T5) .

T7 for example encodes an endonuclease and a 5'->3' exonuclease required for host chromosome degradation. More than 80% of nucleotides used in synthesizing the DNA of T7 progeny derive from the host chromosome .

Viruses that use this strategy must evolve a mechanism by which they can distinguish their own genetic material from that of their host. In the case of bacteriophage T4, a chemical modification of the viral cytidines by a viral specific enzyme provides a simple mechanism for distinguishing between the DNA of the host and the DNA of the phage T4.

Degrading host chromosome provides an advantage during the virus life cycle by reducing or eliminating competing host macromolecular synthesis and shutting off host gene expression. However, host RNAs are not degraded by this mean and host protein synthesis can still go on.

Matching UniProtKB/Swiss-Prot entries

8 entries grouped by protein (browse by keywords)

1 entry

Protein A1

A1_BPT5
Escherichia phage T5 (Enterobacteria phage T5) reference strain

1 entry

Endonuclease II (EC 3.1.21.8)

END2_BPT4
Enterobacteria phage T4 (Bacteriophage T4) reference strain

1 entry

Endonuclease I (EC 3.1.21.2) (Gene product 3) (Gp3) (Junction-resolving enzyme gp3)

ENDO_BPT7
Enterobacteria phage T7 (Bacteriophage T7) reference strain

2 entries

Exonuclease subunit 1 (EC 3.1.11.-) (Gene product 47) (gp47)

Select_allDeselect_all
EXO1_BPT4
Enterobacteria phage T4 (Bacteriophage T4) reference strain
EXO1_BPT5
Escherichia phage T5 (Enterobacteria phage T5) reference strain

Probable exonuclease subunit 1 (EC 3.1.11.-) (D12)

2 entries

Exonuclease subunit 2 (EC 3.1.11.-) (Gene product 46) (gp46)

Select_allDeselect_all
EXO2_BPT4
Enterobacteria phage T4 (Bacteriophage T4) reference strain
EXO2_BPT5
Escherichia phage T5 (Enterobacteria phage T5) reference strain

Probable exonuclease subunit 2 (EC 3.1.11.-) (D13)

1 entry

Exonuclease (Exonuclease gp6) (Gene product 6) (Gp6) (EC 3.1.11.3)

EXRN_BPT7
Enterobacteria phage T7 (Bacteriophage T7) reference strain