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Noncanonical DNA polymerization by aminoadenine-based siphoviruses
Valerie Pezo1, Faten Jaziri1, Pierre-Yves Bourguignon2,3
1Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ. Evry, Université Paris-Saclay, 2 Rue Gaston Crémieux, 91057 Evry, France.
Science (New York, N.Y.)
|April 30, 2021
Summary
Bacteriophages use a modified DNA base, aminoadenine, instead of adenine, forming three hydrogen bonds with thymine. This ancient genetic system, involving specialized polymerases, is widespread in DNA viruses.
Area of Science:
- Molecular Biology
- Virology
- Genetics
Background:
- Bacteriophage genomes exhibit exceptional chemical diversity in nucleobases.
- Some DNA viruses substitute adenine with aminoadenine, forming three hydrogen bonds with thymine.
Purpose of the Study:
- Investigate the role and origin of aminoadenine in bacteriophage DNA.
- Characterize the DNA polymerases involved in aminoadenine incorporation.
Main Methods:
- Analysis of bacteriophage genomes and gene synteny.
- Biochemical characterization of DNA polymerases.
- Phylogenetic analysis of polymerase and biosynthesis genes.
Main Results:
- Aminoadenine-encoded DNA polymerases preferentially incorporate aminoadenine over adenine.
- Polymerase genes are found with biosynthesis genes for aminoadenine deoxynucleotides in many Siphoviridae phages.
- Phylogenetic analysis indicates co-evolution of polymerases and biosynthesis enzymes.
Conclusions:
- Aminoadenine-based DNA replication is a significant feature in diverse bacteriophages.
- This system likely evolved early in the history of DNA-based life.
- The findings reveal an ancient, alternative genetic system within DNA viruses.
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