Other nucleases that might act on internalized DNA

I just discovered a 2008 paper in Mutation Research, about the phenotypes of H. influenzae exonuclease mutants, and I've emailed the senior author asking if they would be willing to send us chromosomal DNA of these mutants, so we could test a pet hypothesis of mine.

The hypothesis concerns the functions of the competence-induced genes comM and dprA. Phenotypes of mutants in other bacteria suggest that the products of these genes protect incoming DNA from nuclease degradation. But what nuclease? By testing the competence phenotypes of double mutants we've ruled out ExoV (recBCD). Using the new mutants would let us test the involvement of other nucleases. (The hypothesis is described more thoroughly in this blog post.)

A 2002 paper about Snyechocystis shows that knocking out recJ increases transformation frequencies 100-fold. Synechocycsis does have homologs of both comM and dprA, so I don't know what the increased transformation implies about their roles.