Disease relevance of denB

• Complementation was at a very low level unless the infecting phage carried a denB mutation (which abolishes T4 DNA endonuclease IV activity) [1].
• Plasmid DNA degradation, like E. coli chromosomal DNA degradation, occurs in wild-type and denB mutant infections [2].

High impact information on denB

• Mutations in the genes for nuclear disruption (ndd), endonuclease IV (denB), and the D1 region of the T4 genome are essential for converting bacteriophage T4 into a generalized transducing phage [3].
• Considerable transactivation can occur, provided that the infecting phage contains a mutation which abolishes the denB-encoded endonuclease, and that the gene 46-encoded exonuclease is functional [4].
• Bacteriophage T4 DNA containing cytosine has been obtained from cells infected with phage mutant in genes 42, 56, denA and denB [5].
• Endonuclease IV encoded by denB of bacteriophage T4 is implicated in restriction of deoxycytidine (dC)-containing DNA in the host Escherichia coli [6].
• These results suggest that Endo IV preferentially recognizes short nucleotide sequences containing 5'-dTdCdA-3', which likely accounts for the limited digestion of ssDNA by the enzyme and may be responsible in part for the indispensability of a deficiency in denB for stable synthesis of dC-substituted T4 genomic DNA [6].

Other interactions of denB

• Most, if not all, host RNA synthesis was shut off after infection of Escherichia coli strain B/5 with a bacteriophage T4 multiple mutant defective in the abilities to induce (i) unfolding of the host nucleoid (unf-), (ii) nuclear disruption (ndd-), and (iii) host DNA degradation (denA-, denB-) [7].

References