In:
Nucleic Acids Research, Oxford University Press (OUP), Vol. 51, No. 17 ( 2023-09-22), p. 9214-9226
Abstract:
Bacteriophages and bacteria are engaged in a constant arms race, continually evolving new molecular tools to survive one another. To protect their genomic DNA from restriction enzymes, the most common bacterial defence systems, double-stranded DNA phages have evolved complex modifications that affect all four bases. This study focuses on modifications at position 7 of guanines. Eight derivatives of 7-deazaguanines were identified, including four previously unknown ones: 2′-deoxy-7-(methylamino)methyl-7-deazaguanine (mdPreQ1), 2′-deoxy-7-(formylamino)methyl-7-deazaguanine (fdPreQ1), 2′-deoxy-7-deazaguanine (dDG) and 2′-deoxy-7-carboxy-7-deazaguanine (dCDG). These modifications are inserted in DNA by a guanine transglycosylase named DpdA. Three subfamilies of DpdA had been previously characterized: bDpdA, DpdA1, and DpdA2. Two additional subfamilies were identified in this work: DpdA3, which allows for complete replacement of the guanines, and DpdA4, which is specific to archaeal viruses. Transglycosylases have now been identified in all phages and viruses carrying 7-deazaguanine modifications, indicating that the insertion of these modifications is a post-replication event. Three enzymes were predicted to be involved in the biosynthesis of these newly identified DNA modifications: 7-carboxy-7-deazaguanine decarboxylase (DpdL), dPreQ1 formyltransferase (DpdN) and dPreQ1 methyltransferase (DpdM), which was experimentally validated and harbors a unique fold not previously observed for nucleic acid methylases.
Type of Medium:
Online Resource
ISSN:
0305-1048
,
1362-4962
Language:
English
Publisher:
Oxford University Press (OUP)
Publication Date:
2023
detail.hit.zdb_id:
1472175-2
SSG:
12
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