Bacteriophage T5 gene D10 encodes a branch-migration protein

Abstract

Helicases catalyze the unwinding of double-stranded nucleic acids where structure and phosphate backbone contacts, rather than nucleobase sequence, usually determines substrate specificity. We have expressed and purified a putative helicase encoded by the D10 gene of bacteriophage T5. Here we report that this hitherto uncharacterized protein possesses branch migration and DNA unwinding activity. The initiation of substrate unwinding showed some sequence dependency, while DNA binding and DNA-dependent ATPase activity did not. DNA footprinting and purine-base interference assays demonstrated that D10 engages these substrates with a defined polarity that may be established by protein-nucleobase contacts. Bioinformatic analysis of the nucleotide databases revealed genes predicted to encode proteins related to D10 in archaebacteria, bacteriophages and in viruses known to infect a range of eukaryotic organisms.

Mitochondrial helicase Irc3 translocates along double‐stranded DNA

“…Constraining the value of L 0 to 17 bp, the two fitted parameter values obtained were V = 60.7 ± 5.9 s −1 and K G = 32.8 ± 6.6 bp. Sequence‐specific effects described for other helicases could explain why some data points do not conform to a perfect hyperbolic fit. However, we cannot rule out a possibility that Irc3 ATPase activity follows a more complex kinetic scheme leading to a sigmoidal dependence on dsDNA length.…”

Similar mechanisms of retron-mediated anti-phage defense for different families of tailed phages

“…The T5 mutants displayed a different pattern. They had single point mutations leading to the replacement of individual amino-acid residues in the C-terminal RecA-like domain of the D10 helicase 25 ( Figure 5A ). D10 is a functional homolog of UvsW, and both proteins belong to the SF2 helicase family 26,27 .…”