Restriction-modification system evasion by virus

The restriction-modification (RM) system is a defense mechanism present in over 90% of sequenced bacterial and archeal genomes. Its consists of a modification enzyme that methylates a specific DNA sequence in a genome and a restriction endonuclease that cleaves DNA lacking this methylation .

Bacterial viruses have evolved different strategies to evade the restriction-modification system . Some viruses encode their own methyltransferase in order to protect their genome from host restriction enzymes . Instead, bacteriophage T7 encodes the OCR protein that blocks the active site of several restriction enzymes by mimicking the phosphate backbone of B-form DNA. Other bacterial viruses use unusual bases on their genome to avoid restriction. Bacteriophages SPO1, SP82, and 2C replace thymidine with 5-hydroxymethyluracil while phages PBS1 and PBS2 thymine is completely changed to uracil.

Family Genus Virus Strategy of RM evasion Viral protein Ref.
Siphoviridae Tunalikevirus Bacteriophage T1 Viral methyltransferase Dmt methyltransferase
Podoviridae T7likevirus Bacteriophage T3 Viral SAMase S-adenosyl-L-methionine hydrolase
Myoviridae T4likevirus Bacteriophage T4 Viral methyltransferase Dam methyltransferase
Myoviridae T4likevirus Bacteriophage T2 Viral methyltransferase Dam methyltransferase
Podoviridae T7likevirus Bacteriophage T7 Inhibition of type-I RM enzymes OCR protein
Myoviridae Punalikevirus Bacteriophage P1 Internal capsid protein DarA, DarB
Podoviridae P22likevirus Bacteriophage P22 Modification of host methylase activity Ral
Siphoviridae Lambdalikevirus Bacteriophage λ reverse Modification of host methylase activity Lar
Siphoviridae Lambdalikevirus Bacteriophage λ Modification of host methylase activity Ral
Myoviridae Mulikevirus Bacteriophage Mu Adenine acetyltransferase Mom

Matching UniProtKB/Swiss-Prot entries

16 entries grouped by strain (browse by keywords)

All proteins are shown (view only 14 complete proteome entries)

5 entries

Enterobacteria phage T4 (Bacteriophage T4) reference strain

Select_allDeselect_all
STP_BPT4 T4 Suppressor of prr (Stp)
ARN_BPT4 Anti-restriction endonuclease (Anti-rgl nuclease)
GSTB_BPT4 DNA beta-glucosyltransferase (BGT) (Beta-GT) (EC 2.4.1.27)
GSTA_BPT4 DNA alpha-glucosyltransferase (AGT) (Alpha-GT) (EC 2.4.1.26)
DMA_BPT4 DNA adenine methylase (EC 2.1.1.72) (DNA-(N(6)-adenine)-methyltransferase) ...

3 entries

Escherichia phage P1 (Bacteriophage P1) reference strain

Select_allDeselect_all
DARA_BPP1 Defense against restriction protein A (DarA)
DARB_BPP1 Defense against restriction protein B (EC 3.6.4.-) (DarB)
DMT_BPP1 Methyltransferase Dmt (EC 2.1.1.-)

1 entry

Enterobacteria phage T3 (Bacteriophage T3) reference strain

ADOM_BPT3 S-adenosyl-L-methionine hydrolase (ADOMetase) (Adenosylmethionine hydrolase) (SAMase) (EC 3.3.1.2)

1 entry

Enterobacteria phage T7 (Bacteriophage T7) reference strain

OCR_BPT7 Overcome classical restriction gp0.3 (Gene product 0.3) (Gp0.3) (OCR)

1 entry

Escherichia phage Mu (Bacteriophage Mu) reference strain

MOM_BPMU Adenine modification enzyme mom (Adenine acetyltransferase) (EC 2.3.1.-) (Gene product 55) (gp55) ...

1 entry

Escherichia phage lambda (Bacteriophage lambda) reference strain

RAL_LAMBD Restriction inhibitor protein ral (Antirestriction protein)

1 entry

Salmonella phage P22 (Bacteriophage P22) reference strain

RAL_BPP22 Restriction inhibitor protein ral (Antirestriction protein)

1 entry

Enterobacteria phage T2 (Bacteriophage T2)

DMA_BPT2 DNA adenine methylase (EC 2.1.1.72) (DNA-(N(6)-adenine)-methyltransferase) ...

1 entry

Enterobacteria phage phi21 (Bacteriophage phi-21)

RAL_BPPH3 Restriction inhibitor protein ral (Antirestriction protein)

1 entry

Escherichia phage D108 (Bacteriophage D108)

MOM_BPD10 Adenine modification enzyme mom (Adenine acetyltransferase) (EC 2.3.1.-) (Gene product mom) (gpMom) ...