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7-Deazaguanine modifications protect phage DNA from host restriction systems
Geoffrey Hutinet1, Witold Kot2, Liang Cui3
1Department of Microbiology and Cell Science, University of Florida, Gainesville, FL, 32611, USA. ghutinet@ufl.edu.
Nature Communications
|December 1, 2019
Summary
Viruses utilize novel 7-deazaguanine DNA modifications, including archaeosine (G+), to evade host defenses. These modifications protect viral genomes from restriction enzymes, highlighting a key viral survival strategy.
Area of Science:
- Microbiology
- Virology
- Biochemistry
Background:
- Viral genomes undergo modifications as part of host-virus coevolution.
- Archaenosine (G+) was previously identified in archaeal tRNAs and Enterobacteria phage 9g DNA, suggesting a role in evading restriction enzymes.
Purpose of the Study:
- To identify novel 2'-deoxy-7-deazaguanine modifications in viral genomes.
- To investigate the prevalence and function of these modifications in phage-host interactions.
Main Methods:
- Bioinformatic analysis of viral genomes to identify enzymes involved in 7-deazaguanine biosynthesis.
- Genetic studies using Escherichia phage CAjan to assess the role of DpdA in DNA modification and phage survival.
Main Results:
- Three new 2'-deoxy-7-deazaguanine modifications (dADG, dPreQ0, dPreQ1) were identified in viruses.
- 180 phages/archaeal viruses encode enzymes for this pathway, with 60% targeting pathogenic hosts.
- DpdA is essential for incorporating 7-deazaguanine bases into phage DNA, conferring protection against restriction enzymes.
Conclusions:
- The 7-deazaguanine modification pathway is widespread in viruses, particularly those infecting pathogenic microbes.
- These DNA modifications are crucial for protecting viral genomes from host restriction systems, enhancing viral fitness.
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