Characterization of a reverse transcriptase activity associated with retrovirus-like particles in a Drosophila cell...

The properties of an endogenous RNA-dependent DNA polymerase (reverse transcriptase) associated with retrovirus-like particles (VLP) in a Drosophila melanogaster cell line were characterized. The enzyme requires a monovalent and a divalent cation, a sulfhydril-reducing agent and the four deoxynucleosides triphosphates for a maximal activity. The reaction was enhanced by a detergent and was sensitive to a DNA-A-free RNA-A indicating that the enzymatic activity was indeed associated with VLP which contain intrinsic RNA. The maximal incorporation of the labelled deoxynucleotide was observed at 25 degrees C in the presence of Mn2+. The enzyme responded well to exogenous template-primers in the similar way to that of retroviral reverse transcriptase and the use of several inhibitors confirms the presence of a real reverse transcriptase activity associated with virus-like particles in drosophila cells.