Two exceptions to the generality of heterologous complementation are pertinent here: T7 and T3 RNA polymerase (gene 1 product) do not recognize the heterologous promoter, and, whereas T3 gene 1.2 is essential for phage growth on F plasmid-containing strains, T7 gene 1.2 is one cause of an abortive infection on those strains [52]. The gene discussed is SLC25A5; the disease is infection.