Methylation and cleavage sequences of the EcoP1 restriction-modification enzyme

Bächi, Brigitte; Reiser, Jakob; Pirrotta, Vincenzo

doi:10.1016/0022-2836(79)90123-2

Cited by 90 publications

(43 citation statements)

References 25 publications

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“…Such phages were in fact included in the data sampling used for Figure 4, and presumably contribute to total diversity. Furthermore, a bacterial strain, where parts of the population contain a temperate prophage, may appear as two strains with different immunity to some virulent phages as immunity can be provided by some prophages (Bachi et al, 1979;Parma et al, 1992). Hence, presence of temperate phages may supplement the natural immunities of bacteria (Makarova et al, 2013) and thereby further increase the sustainable diversity of virulent phages.…”

Section: Resultsmentioning

confidence: 99%

Phage and bacteria support mutual diversity in a narrowing staircase of coexistence

2014

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The competitive exclusion principle states that phage diversity M should not exceed bacterial diversity N. By analyzing the steady-state solutions of multistrain equations, we find a new constraint: the diversity N of bacteria living on the same resources is constrained to be M or M þ 1 in terms of the diversity of their phage predators. We quantify how the parameter space of coexistence exponentially decreases with diversity. For diversity to grow, an open or evolving ecosystem needs to climb a narrowing 'diversity staircase' by alternatingly adding new bacteria and phages. The unfolding coevolutionary arms race will typically favor high growth rate, but a phage that infects two bacterial strains differently can occasionally eliminate the fastest growing bacteria. This contextdependent fitness allows abrupt resetting of the 'Red-Queen's race' and constrains the local diversity.

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Section: Resultsmentioning

confidence: 99%

Phage and bacteria support mutual diversity in a narrowing staircase of coexistence

2014

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“…The enzyme is probably virus encoded and is isolated from a eucaryotic organism. Virus-encoded restriction endonuclease-like activity has previously been found in some E. coli strains carrying P1 prophage (1,2,16) and in the blue-green alga Anacystis nidulans PCC6301 infected with the phage AS-1 (24,25). Unlike the PBCV-1-induced enzyme, the AS-1-induced enzyme ultimately degrades substrate DNA to very small fragments.…”

Section: Resultsmentioning

confidence: 99%

“…The homogenate was centrifuged at 10,000 x g for 20 min; the supernatant was frozen at -20°C, thawed at 4°C, and centrifuged at 16,000 x g for 30 min. This freeze-thaw and centrifugation treatment precipitated most of the green color and yielded a clear supernatant fraction (fraction 1). The following components were added per milliliter of supernatant: 0.5 ml of denatured salmon sperm DNA at 5 mg/ml in 0.01 M Tris hydrochloride (pH 7.9), 0.001 M EDTA, 0.6 g of polymer concentrate (7% [wt/wt] dextran T500, 28% [wt/wt] polyethylene glycol 6000 [21]), and 0.64 ml of 4 M NaCl.…”

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confidence: 99%

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Restriction endonuclease activity induced by PBCV-1 virus infection of a Chlorella-like green alga.

Xia¹,

Burbank²,

Uher³

et al. 1986

Mol. Cell. Biol.

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An enzyme was isolated from a eucaryotic, ChloreUla-like green alga infected with the virus PBCV-1 which exhibits type II restriction endonuclease activity. The enzyme recognized the sequence GATC and cleaved DNA 5' to the G. Methylation of deoxyadenosine in the GATC sequence inhibited enzyme activity. In vitro the enzyme cleaved host Chlorella nuclear DNA but not viral DNA because host DNA contains GATC and PBCV-1 DNA contains GmATC sequences. PBCV-1 DNA is probably methylated in vivo by the PBCV-1-induced methyltransferase described elsewhere (Y. Xia and J. L. Van Etten, Mol. Cell. Biol. 6:1440 1445). Restriction endonuclease activity was first detected 30 to 60 min after viral infection; the appearance of enzyme activity required de novo protein synthesis, and the enzyme is probably virus encoded. Appearance of enzyme activity coincided with the onset of host DNA degradation after PBCV-1 infection. We propose that the PBCV-1-induced restriction endonuclease participates in host DNA degradation and is part of a virus-induced restriction and modification system in PBCV-1-infected Chlorella cells.We have previously characterized a large polyhedral virus, PBCV-1, which infects and replicates in a unicellular, eucaryotic Chlorella-like green alga, strain NC64A. The virus contains a large double-stranded DNA genome (ca. 300 kilobase pairs as estimated by summing restriction fragments), at least 50 structural proteins, and a lipid component (22,29). The virus can be assayed by plaque formation, and milligram quantities can be produced in culture (27, 28). PBCV-1 infection is synchronous, and progeny virus is first released at 3 to 4 h postinfection; by 6 to 8 h virus release is complete. The virus has a burst size of 200 to 350 PFU per cell (28).Studies on DNA synthesis after PBCV-1 infection established that viral DNA synthesis begins about 45 min after infection; host DNA synthesis ceases immediately after infection, and host nuclear and chloroplast DNAs are degraded beginning about 60 min after infection (26). Base analyses of Chlorella nuclear and PBCV-1 DNAs revealed that the host DNA contains 21% 5-methyldeoxycytidine

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“…Possibly the second methylation negates the effect of CmCGG. m) Type III restriction endonuclease (1,26). n) There is a report that Hin C II does not cut GTYRAmC (27).…”

Section: Introductionmentioning

confidence: 99%