2A-04 Inverted repeat formation during genetic transformation of the filamentous fungus Aspergillus nidulans

During genetic transformation interaction of vector DNA molecules occurs. This results in the formation of a multimer that is commonly arranged as a direct repeat (DR), but rarely as an inverted repeat (IR), regardless of whether integration into a chromosome occurs. Because physical and random collision of molecules should result in an even ratio of DR and IR multimers, the dominance of DR over IR formation can be used as a tool to investigate the molecular mechanisms of exogenous DNA integration into a chromosome. To identify the cause for the observed bias towards DR integration, we constructed, in vitro, IR-configured vector and examined the effects during trans-formation of A. nidulans with a linear vector (LV). Compared with transformation by the LV alone, addition of IR-configured vector suppressed transformation in several independent experiments. In parallel, by analyzing the integration profiles it was revealed that addition of IR-configured did not stimulate integration event as sole IR.