FIG. 6.

An enlarged polymerase is more sensitive to PcG repression. (A) Drawing comparing wild-type T7RNAP and Goliath polymerase. (B) Pattern of Goliath polymerase protein in the CNS Goliath line in a germ band retracted embryo. The location of Goliath polymerase was detected with a monoclonal antibody to β-galactosidase. PS5, the anterior limit of bx enhancer activity, is indicated with a bracket. (C) Transcription by Goliath polymerase on the 4× T7 promoters in the bx control region in a germ band retracted embryo. Transcription by Goliath is blocked anterior to PS5. (D) Transcription by Goliath polymerase in an extra sex combs mutant embryo (esc²/esc¹⁰, maternal and zygotic null). The repression in anterior segments is lost. (E to H) T7RNAP versus Goliath polymerase as shown by expression of the polymerases with the Gal4-UAS system. A ubiquitous Gal4 source (line 32B) was used to drive polymerase expression. All embryos are in the germ band extended stage. (E) Goliath polymerase protein pattern marked with an antibody to β-galactosidase. (F) Transcription by T7RNAP on the 4× T7 promoters in the bx control region. Transcription appears unaffected by the PcG. (G) Transcription by Goliath polymerase. Transcription is repressed by the PcG anterior to PS5. (H) Transcription by Goliath polymerase in a Polycomb mutant (zygotic null). Repression in the anterior segments is lost.