Streptococcus agalactiae DNA polymerase I is an efficient reverse transcriptase

Genome annotations result generally from large sequence alignments by bioinformatics. Large scale biochemical data are more difficult to obtain. They derive for example from directed protein evolution experiments by selection. A previously reported directed enzyme evolution experiment by in vitro selection of Stoffel fragment variants of Taq DNA polymerase I was used here to predict the activities of Streptococcus agalactiae DNA polymerase I. The reverse transcriptase activity of S. agalactiae DNA polymerase I was measured and the kinetic parameters for this RNA-dependent DNA polymerase are given. RNA-templated DNA repair is suggested as a possible biological function for this biochemical activity.